ISSUE 01 | 2013

InFocusOptical Measurement Solutions

“Conditions Where No Other Technology

Would Survive“ – Remote Sensing at CERN

Page 5

New Materials at Daimler

Page 14

Market Leader Trusts in Polytec –

Herrmann Ultraschalltechnik

Page 18

Remote Sensing

Safety From Far Away Page 10

NEWS

Register for our News-letter now:

www.polytec.com/newsletter

2

Polytec News

Page 3

Polytec Cooperates with Graduate

School – Promoting Young Talent

Page 4

Polytec Presents Mobile Vibrometer

with Unique Skills – The All-rounder

Page 5

Laser Vibrometers for the Roughest

Conditions – Mission Possible

Page 6

Measurement of Tension Forces on Stay

Cables – No Highwire Act

Page 10

Wilhelminian Style Buildings in Vienna –

Earthquake-proof Buildings

Page 12

NVH CAE Test Correlation of Fiber

Reinforced Plastic Structures – Seamless

Integration

Page 14

Market Leader Trusts in Polytec –

“Our Good Relationship Has Always

Been Appreciated”

Page 18

MAN Counts on Polytec – “Polytec Has

Competence in Laser Measurement

Technology”

Page 21

Product News

Page 24

Editorial

Dear Reader,

Faster, Higher, Stronger!

This Olympic motto is enough to inspire any sports enthusiast. The statement

can also be applied to measurement technology and to recent developments at

Polytec. Many of you will already be familiar with the benefits of non-contact,

optical measurement systems. Because the optical approach does not affect

the test object in any physical way, there is no distortion of results – a real ad -

vantage over more traditional, tactile techniques. The optical sensor will also

access points that are impossible or difficult to reach in any other way. For

situations that involve measuring objects from a distance, Polytec provides

the RSV Remote Sensing Vibrometer.

In this issue of InFocus, find out how our new measuring instrument is respond-

ing to the challenges of vibration engineering at the European Organization

for Nuclear Research (CERN) and how it monitors the condition of bridges at

dizzying heights. Broadening the discussion further, we also explore the opti-

mization and production control of ultrasonic equipment, as well as the latest

on designing lightweight materials for the automotive industry. As ever, this

issue of InFocus offers insights into various fascinating topics.

We hope you will enjoy reading the articles.

Eric WinklerHead of Optical Measurement Systems

Dr. Hans-Lothar PaschManaging DirectorPolytec GmbH

Dr. Hans-Lothar PaschEric Winkler

3

News

Singapore

Polytec Expands

Polytec’s wholly-owned subsidiary, Poly-tec South-East Asia Pte Ltd., was opened at the beginning of 2013 in Singapore. It will exclusively serve all HDD manufac-tures and suppliers in this region. The total floor area of 260 m2 leaves enough space for future expansion and includes meeting and demonstration areas for seminars and equipment presentations.

Polytec Satisfies Demand

Modaltest 2.0

The new RoboVib® Structural Test Station performs 3-D modal testing in a fraction of the time required by conventional methods such as accelerometers. A 90% average time reduction was achieved compared to the industry norm. At the same time the spatial resolution was dra-matically increased, bringing the result-ing data files closer to the optimal Finite Element model’s validation requirements.The Test Center is designed to meet in-creasing demand for external testing capacity.

More Infowww.polytec.com/robovib

4

News

Although top executives are keys to suc-cess, Polytec emphasizes development and recruitment of young talent as well.The various paths that are available in-clude an internship program for junior staff. Polytec has cooperated with the Karlsruhe School of Optics and Photonics (KSOP) since 2006. KSOP is one of the excellence status graduate schools of the Karlsruhe Institute of Technology (KIT). About 100 Masters and 100 PhD students from 40 nations conduct research on multi -disciplinary topics in optics and photonics.

Thanks to highly selective scholarship funding from Polytec GmbH and other partner companies, outstanding talent is attracted to Germany with a first de -gree in physics, mechanical engineering, electrical engineering, chemistry or biol-ogy. The KSOP encourages early contact of its students with these partner com-panies. Polytec in particular uses this op-portunity for strategic human resource development and prepares the suitable candidates in practical research phases for meeting the special needs of our

Polytec Cooperates with Graduate School

Promoting Young Talents

optical department for example. Along with the technological know-how that these students acquire at KSOP, junior employees from abroad become quali-fied for a career in a German corporate working environment.

Waiz Karim, a Masters graduate of KSOP,was an intern at Polytec: “I got a chanceto interact closely with the software andelectronic development team leading to a successful interdisciplinary project on diversity reception in long-distance IR Laser Doppler Vibrometry. Working atPolytec has been a unique experience.”

Contact · More InfoFor more information about the Karls-ruhe School of Photonics (KSOP) visitwww.ksop.de/master

5

Polytec’s RSV-150 Remote Sensing Vibro-meter marks the beginning of a new ge neration of vibrometers. It opens up a multitude of new opportunities from condition monitoring of bridges and in -dustrial plants to ultrasonic applications to elementary particle research.

A new laser technology made it pos-sible to significantly increase the working range of the RSV-150. It allows precise measurements even over a distance of several hundred meters and on nearly all surfaces. Thanks to the eye-safe class-2 laser the device can be used anywhere without any particular safety measures.

The RSV-150 measures precisely on tar-get on bridges, buildings or industrial plants even on points which are difficult to ac cess and from a safe distance in a dangerous situation, such as where there is high voltage, heat, radiation or risk of explosion. It has proven its worth under tough conditions during inspections of railway bridges at the German railroad company Deutsche Bahn.

Vibration Measurement Technology

Polytec’s RSV-150 Remote Sensing Vibro-meter marks the beginning of a new

The RSV-150 measures precisely on tar-get on bridges, buildings or industrial

Polytec Presents Mobile Vibrometer With Unique Skills

All-rounderPolytec’s Laser-Doppler-Vibrometry technology

has during recent decades become an indispen-

sable tool for precisely measuring vibration and

displacement in both research and industry.

More Infowww.polytec.com/rsv

6

Material Research

Fig. 1: Sample holder with 6 different materials.

Laser Vibrometers for the Roughest Conditions

Mission PossibleThe introduction in recent years of new, extremely energetic

particle accelerators such as the Large Hadron Collider (LHC)

at the European Organization for Nuclear Research (CERN)

brought about the need for advanced beam cleaning and

protection systems in order to safely increase the energy and

intensity of particle beams to unprecedented levels.

© C

ERN

7

cylinders with a half-moon cross section for high intensity tests, allowing extreme surface phenomena (melting, material splashes, debris projections etc.) to be visualized and optically acquired.

Measurement Instrumentation

Remote optical devices (the RSV-150 laser Doppler vibrometer and a high speed camera) were placed in a radia-tion-protected bunker, 40 m upstream of the sample holder (Fig. 2 and 3). The RSV-150 measured the radial velocity on the outer surface of one cylindrical sam-ple per tier. A system of Polytec mirrors (Fig. 4) was assembled and accurately aligned in order to reflect the laser beam back to the vibrometer, positioned inside the protected bunker. In order to be able to measure the response predicted using beam impact simulations, a RSV-150 was customized to achieve a measurement bandwidth of 2.5 MHz and amplitude range of 24 m/s. The signal output delay of the RSV-E-150-M controller was also a major issue for this measurement (parti-cle beams arrive at a speed close to that of light).

Results and Conclusions

The arriving proton pulse was used to trig ger the RSV-150, and the subsequent vibration measurement was collected for 13 ms with a sampling frequency of 4 MHz, although the first pressure wave typically occurs within the first few micro-seconds. Typical traces of strain and radial velocity raw signals are shown in Fig. 5 below. This event corresponds to the impact of 4.6 x 1012 protons on the Glidcop® samples. In this event, the beam impacted the samples at 22 μs (t0). Ò

under proton beams of different intensity, at an energy level of 440 GeV. The mate-rial specimens and their housing were designed and equipped to measure phy-sical quantities in real time such as axial and hoop strains, radial velocity of dis-placement and temperature necessary to reconstruct material constitutive models. Data were collected at very high sampling rates to fit shock wave profiles with suffi-cient accuracy. The projection of particles generated by the beam impact was filmed by a high-speed camera. The material sample holder comprises a vacuum ves-sel and a specimen housing featuring 12 material sample tiers arranged in two rows of six. The specimen housing could be accurately positioned via a two de -grees-of-freedom actuation system. Two different specimen shapes were chosen for each material to be tested: a cylindri-cal geometry for medium intensity tests, to measure simple-shaped shock waves, benchmarking numerical simulation; and

Predicting the consequences of highly energetic particle beams accidentally im pacting protection devices, such as collimators, is a fundamental issue in the design of particle accelerators. Such complex dynamic phenomena, entail-ing material phase transitions, extend-ed density changes, shock wave propa-gation, explosions, material fragment projections etc., have been successful-ly simulated using highly non-linear numerical tools (Hydrocodes). In order to gather experimental data for a com-prehensive characterization of relevant materials, a specific test was performed in October 2012 at the CERN HiRadMat (High Radiation to Materials) Facility.

Experimental Setup

The experimental setup consisted of a multi-material sample holder allowing the testing of six different materials (Fig. 1)

© C

ERN

8

Material Research

The high frequency response and dyna-mic range of the RSV-150 allows us to evaluate the pressure wave velocity inside the sample (time between t0 and the first peak at 26 μs). Experimental results con-firm the simulation’s prediction of a pres-sure wave velocity around 4000 m/s in

this material. These results also confirm the main advantages of the RSV-150 for this very harsh environment: strain gage signals are lost during the first few microseconds after the impact, pos-sibly due to capacitive coupling effects and electromagnetic phenomena. The

RSV-150 data shows only a small pertur-bation before the impact, probably ex -plained by interference between the con-troller and beam passing in front of the radiation-protected bunker, or a possible movement of a mirror installed close to the magnets.

Fig. 5: Strain and velocity results. Fig. 2: General view of the instrumentation structure.

Distance of 40 m

MirrorMirror

RSV-150 Vibrometer

High Speed Camera

NI® SolutionPXle frame

Temperature Probes (Pt100)

Vacuum Gage

ResistiveStrain Gage

Flash System

618 Wires

266 Wires (40 m) – Existing Structure

Hardware control from the surface (+60 m):■ Switch positions depending on the materials tested■ Control/activation of the flash system■ Positioning of the sample holder

Trigger GPN

Rad-Hard SWITCH

© C

ERN

© C

ERN

Author · ContactMichael Guinchardmichael.guinchard@cern.ch

Responsible of the Mechanical Measurement Lab

Engineering Department, Mechanical and Materials Engineering Group

CERN – CH 1211 Geneva 23

This contribution is based on the publi-cation A. Bertarelli et al., “High Energy Tests of Advanced Materials for Beam Intercepting Devices at CERN HiRadMat Facility”, 52nd ICFA Advanced Beam Dynamics Workshop on High-Intensity and High-Brightness Hadron Beams, 17th

to 21st September, 2012 – Beijing, China, http://jacow.ihep.ac.cn/pls/hb2012/MOP240.PDF

Fig. 4: View of the samples through a Polytec mirror and glass window.

Fig. 3: RSV-150 laser Doppler vibrometer placed in the bunker and view towards the setup from 40 m distance.

© C

ERN

© C

ERN

9

Mr. Guinchard, how did the laser vibrometer contribute to finding the Higgs particle?

The RSV-150 has not directly contrib-uted to identifying new particles, but the measurements performed during this experiment on advanced materials will improve beam intercepting devices for the LHC accelerator. These will be used to explore a higher luminosity and energy range.

How did the vibrometer help in solving or avoiding current problems?

At CERN, we have a lot of experiencemeasuring mechanical effects in very harsh environmental conditions. How-ever this experiment concentrated many critical conditions such as: vacuum con-

ditions, high level of radiation (dose cal-culations had shown a radiation level of 250 kGy integrated), proton beam a few millimeters away from the sensors, and very fast physical effects. The radial ve-locity measurement on the samples was also considered crucial information with redundancy provided with strain meas-urement at the surface of the samples. There are no modern contact sensors able to survive these environmental con-ditions, and an optical measurement with out contact, with remote electronic devices, was the best approach. The RSV-150 fulfilled these requirements.

What would have been the alterna-tives to vibrometry?

As explained before, there are no contact sensors that could withstand these harsh

conditions, and the requirement was also very tight. When the beam impacts the sample, the shock wave travels with a speed around 4,000 m/s in the sample and generates a radial velocity at the sur-face close to 24 m/s with a resonant fre-quency around 120 kHz. These conditions do not permit using any technology other than laser Doppler vibrometry!

How was the cooperation and support from Polytec?

The RSV-150 used for this measurement was customized for this specific applica-tion in order to improve the bandwidth up to 2.5 MHz. Polytec provided a lot of support to perform reflectivity tests on the real samples, and preliminary valida-tion tests at CERN using the real distance coupled to the mirrors’ positions.

Interview with Michael Guinchard on his Experiences with Laser Doppler Vibrometry

Responsible for the Mechanical Measurement Lab,

Mechanical and Materials Engineering Group, CERN

© C

ERN

10

Maintenance

Measurement of Tension Forces on Stay Cables

No Highwire Act

RSV-150 in action during the construction of the Deh Cho Bridge in Canada.

Using laser-based vibration measurement, the calculation

of tension forces in cables can be achieved quickly, with

little work, and with the highest accuracy possible.

11

There are many obvious advantages to cable stay bridges over alternatives such as the arch design. The appeal of these structures lies in the cost efficiency of con -struction as well as the attractive appear-ance of the bridges themselves. However neither of these issues takes precedence over the safety of the stay cables, the main structural elements hold ing the deck in place. The stay cables are in most cases not thoroughly inspected over the years.

Load imbalances that can have a negative impact on the service life of the bridge may occur due to corrosion, slippage, or settlement of all or part of the structure. Other events such as impacts, fire or seis-mic movement can have a significant impact on cable force distribution, influ-encing the fatigue life of the cables. Poly-tec and Metro Testing have successfully teamed up to provide non-contact laser based vibration analysis services to bridge engineering firms and bridge owners alike, providing them with information about the tension forces acting on each individual cable of their structures.

Advantages of the RSV

Since this testing method is non-contact and non-invasive, there is no need to attach any transducers to the cables or have direct access to the cable being measured. The laser vibrometer is locat-ed on the bridge deck and the engineer aims the laser, roughly perpendicular, onto the one-third or mid-point of the cable. The instrument detects laser light scattered back from the cable and pro-vides a velocity or displacement output. This allows the engineer on site to meas-ure areas or objects that are impossible or difficult to reach by normal means.

Since no special mounting equipment is required on the bridge deck, measure-ments can be performed quickly and efficiently, with speeds of up to six min-

utes per cable, or 10 cables per hour under good weather conditions.

Customers receive a report after comple-tion of the testing that includes a com-plete overview of the tension forces in all of the cables. The Polytec/Metro Testing Team in cooperation with the structural engineering firm or bridge designer can then use this data to evaluate the struc-ture.

Locked coil cables installed on the Deh Cho Bridge near Fort Providence in Canada’s Northern Territories were measured during construction of the bridge. The data collected and the ten-sion forces calculated provided informa-tion to the bridge engineer and erection engineering firm that was vital for the final completion of the bridge. All 24 cables were measured within a period of 4 days on site. The challenges of this project included the logistics of position- ing the equipment on the temporary bridge deck and its movement from location to location. Two different exci-tation methods were used to determine the natural frequencies, which were then used to calculate the tension forces of the cables.

The non-contact vibration approach is recognized by the research community and its results generally match those generated by more traditional methods such as the use of accelerometers.

In addition to the non-contact advan-tage, no rigging equipment is required to meas ure at the one-third or mid-point of a cable. Just a simple line of sight, to the measurement point, roughly perpen-dicular to the cable, is all that is required to achieve extremely accurate measure-ments with this technology.

In contrast with traditional methods, this technology does not require a lift off of the cable, strand at the anchorage or

attachment of a sensor to the cable. In some cases the use of jacking equipment on the bridge deck is not an option due to access restrictions or inability to access the cable strands. In most cases the cost of providing the jacking equipment and the resulting logistics outweigh the laser-based alternative.

The Project Partners

Polytec and Metro Testing Laboratorieshave joined forces in a bid to facilitateprocurement of non-contact tension force measurements. Metro Testing has had years of experience performing structural data analysis – calculating the tension force from vibration data. Fast and accurate results are virtually guar-anteed when these skills are combined with Polytec‘s ability to provide long range non-contact vibration measure-ment based on state-of-the-art laser vibrometers.

Deh Cho Bridge (Canada) during construction.

AuthorsMarcus Schmieder, NDT SpecialistMetro Testing Laboratories Ltd

David Oliver, VP Business Development, Polytec Inc.

12

Structural Dynamics

Wilhelminian Style Buildings in Vienna

Earthquake-proof Buildings

Fig. 1: Vibration exciter “HUBERT”.

Fig. 2: PSV-400 Scanning Vibrometer laser sensor head.

Houses that were built somewhere between 1850 and 1914 (the “Gründerzeit” period)

have gained attention in Vienna. These valuable buildings are threatened due to the

introduction of the Euro Code 8 standard (2009), which requires proof of earthquake

safety resulting from structural renovation. The required detection methods are ill-

suited for the modeling of this highly dynamic process and are prone to unfavorable

results. As a result, the proof of earthquake safety will probably fail for houses built

before 1970.

Fig. 5: Layout of the test setup.

Fig. 4: Vibration modes at 11.75 Hzcorresponding to excitation.

Fig. 3: Vibration modes at 4.75 Hz. Excitation after different reinforcement measures (1 – 7).

13

Fig. 5 shows the layout of the test setup for the measurement of the entire build-ing. The exciter was located on the 4th and 5th floor and was operated at fre-quen cies of 4.75 Hz and 11.75 Hz. The PSV-400 laser sensor head was placed on the pavement edge so as not to affect either traffic or pedestrians (fig. 2).

Remedial Measures and their Impact

In the course of the restoration work, the following upgrade measures (1 – 7) were monitored. Figures 3 and 4 show the deflection shapes of the measure-ments in a given state with the maximum deflection at the excitation frequencies 4.75 Hz and 11.75 Hz respectively.

1. Unchanged original state. This meas-urement was used as a reference so that all of the upgrade measures could be assessed quantitatively.

2. The ceiling beams were braced with the outer wall by means of threaded rods. Thus a direct connection bet-ween the ceiling and the wall was estab-lished. Previously, it was assumed that the ceiling would respond to the exci-tation like a single disc, independent of the outer wall. This was proven by the measurement as well.

3. Balk clamped by the adjacent partition walls with threaded rods, which causes a direct connection of the ceiling of the adjacent rooms.

4. OSBs (oriented strand boards) screwed to the ceiling (from above or from be-low). This measure effects an increase in the shear stiffness of the ceiling.

5. Concrete slab poured in the attic. After this step, a slight decrease can be seen due to the additional mass in the upper part of the structure observed in rela-tion to the maximum vibration veloc-

A series of Grunderzeit buildings were investigated, within the framework of the SEISMIDR research project, for their dynamic behavior during earthquakes. The project included analyses on brick and mortar samples as well as the de vel opment and calibration of finite element models. Of particular interest was the measurement-based proof of structural upgrades provided by using both BRIMOSR-Wireless and Polytec PSV-400 Scanning Laser Vibrometer sys-tems. En hanced measurements using the PSV-400 created a significant added value, because the impacts of upgrade measures could be impressively demon-strated just a few seconds after the measurements.

Object under Test and Experimental Setup

The work focused on a particular building in the Fendigasse (fifth municipal district of Vienna) which was selected for a refur-bishment.

This structure offered the opportunity to specifically examine various stages ofrenovation and upgrading. Special em -phasis was placed on interior walls andwooden ceilings, as well as on the dynam -ic behavior of the structure as a whole.With the aid of the Scanning Vibrometerthe velocity field of a structure can be determined, visualized, and analyzed. The measurement points must be visible from the observation point and must be accessible within the scan angle of the sensor head. To be able to relate the series of measurements to each other, a reference sensor is required at a repre-sentative fixed point of the building. The measurements were performed both at ambient excitation, and when induced by a special vibration exciter that had been jointly developed by the project partners (“HUBERT”, fig. 1).

Authors · Contact Dipl.-Ing. (FH) Martin Fritz, Priv. Doz. Dr. Fritz Kopf, Prof. Dr. Helmut Wenzel

fritz@vce.at

VCE Vienna Consulting Engineers ZT GmbH, 1140 Vienna, Austria

ities in the range of 12 Hz. In return, the building responded to the local homogeneous excitation.

6. Fire walls were introduced for drawing fire from the basement walls to the roof, which can be described as a con-crete slab. This measure had a particu-larly high impact in terms of vibration velocity response

7. Final state: concrete and steel struc-tures finished, ceiling windows rein-forced in the 3rd and 4th upper floor. A further decrease in the vibration velocities can be determined during analysis of the measurement.

Conclusions

Because the effects of structural changescan be represented graphically within a few seconds after the measurement, PSV-400 Scanning Vibrometer results offer significant value for the metro-logical impact of remedial measures to Wilhelminian style buildings and houses.

Measurements are especially excellent on the outer facade after the modifica-tions have taken place . The individual steps produce a partial redistribution of the vibrational energy to several parts of the building. The maximum effective-ness, however, is only achieved if all measures are set at the same time. To conclude, it is relatively easy and at the same time inexpensive to significantly improve the vibration behavior of the building during an earthquake.

14

NVH CAE Test Correlation of Fiber Reinforced Plastic Structures

Seamless Integration

Composite Materials

Expanding individual and public mobili-ty is essential for a globalized world. To address demands for reducing carbon dioxide emissions, lightweight fiber rein-forced plastic (FRP) is about to replace traditional steel and aluminum materials in cars and airplanes. FRP is a composite material made from a polymer matrix rein-forced with fibers of glass or carbon for example. The challenge for the design engineer is that the structural dynamic

properties of FRPs are not easy to simu-late due to their anisotropic and inhomo-geneous composition. An experimental validation of eigenfrequencies and eigen-modes was conducted on simple FRP structures as well as on manufactured automotive trunk lids. The goal was to verify the quality of the chosen simula-tion approaches and the modeling parameters.

Fig. 1: Measured samples, an FRP plate (left) and a closed Z profile (right).

15

Structural Dynamics: A New Approach in the Finite Element (FE) Model Validation Process

In the model validation process, the struc-tural FE model is compared to a dynamic structural model derived from experimen-tal data. Experimental Modal Analysis (EMA) delivers the modal parameters (eigenfrequency, modal damping, modeshape) out of the measured set of Fre-quency Response Functions (FRFs), which characterize the dynamic behavior of the tested structure. The modal parameters derived from both methods – Test andCAE – are compared, and the correlation allows the verification and fine tuning of the FE modeling parameters. A validated FE model enables more accurate pre-dictions and simulation of “what if” sce-narios in the product design process.In order to get high-quality experimental data that can be used for model valida-tion, several conditions need to be met.

Among them are the precise mounting of the test object, appropriate excitation, minimal influence of the measurement itself on the test data, and a suitable grid of measurement locations. The traditional test procedure requires mounting accel-erometers at a number of measurement points and performing the test under the influence of this added mass and cabling. Besides the mass and stiffness influences through the use of tactile sensors, this traditional method requires a manual defi-nition of the test grid and the global and local (Euler angles) coordinate systems of the test object. In this work, a new ap-proach is proposed allowing the use of FE geometry data for defining the test grid together with an optical 3-D scan-ning laser vibrometer system combined with robotics.

Optical methods allow relatively easy work with test grids that are derived from the existing FE geometry of the object under test.

Being free from the constraints of physi-cally mounted and cabled sensors, two major shortfalls of conventional testing methods are overcome: the limited spa-tial density of measurement nodes, and mass loading through tactile response sensors. Overcoming those constraints, the measured data is much closer to the “real” behavior of the test object and, due to the high grid density, it’s possible to achieve a more precise comparison with the simulated model. Therefore the Modal Assurance Criterion (MAC) values between the Test and CAE models are considerably improved. This approach enhances the model updating process significantly, as more reliable target data and accurate data sets are available for the model correlation.

RoboVib: A Fully Automated Robot-based 3-D Laser Doppler Scanning Vibrometer

After importing the FE geometry into the Polytec RoboVib workstation, the optical 3-D FRF measurements can be automati-cally performed exactly at the nodal co-ordinates from the FE model. The global coordinate systems of the FE and Test geometry are aligned automatically – the nodal response vectors are directly meas-ured in the global coordinate system of the test object. Thus, the results of a sub-sequent experimental modal analysis can easily be compared and matched to the FE simulation results.

Case Study I: Simple FRP Structures

In a first step, an experimental validation of eigenfrequencies and eigenmodes was conducted for some simple FRP structures such as various plates and a closed Z pro-file (fig. 1), which has been modeled in NASTRAN. A test grid was then derived from the original FE mesh as preparation for the modal test. The aim was to excite

all modes in the range of 0 Hz to 1,000 Hz from one shaker position, and to find an ideal mounting method for the force sensor not influencing the eigenmodes.

Prior to the measurement, the samples were mounted under free–free boundary conditions. A Polytec PSV-400-3D Scan-ning Vibrometer was used to measure the 3-D response vector at each measurement point. The three scan heads are mounted on the robot arm, which allows for fully automated positioning around the entire object surface (fig. 2). Ò

Fig. 2: Test setup for the sample plate.

16

Composite Materials

The experimental and numerical eigen-frequencies and MAC values were then correlated using the NX Correlation tool. Fig. 3 shows examples of computed modes extracted from the measurement results of the closed Z profile, and fig. 4 the respective MAC analysis.

It can be seen that the agreement is very good – the lowest MAC value is still above 0.85 and the frequency error is small.

Case Study II: Modal Analysis of Trunk Lids

Further tests were performed on a series of trunk lids (fig. 5) provided by Daimler to obtain data for an experimental modal analysis. The trunk lids have a pure poly-mer topside supported by a crossbeam made from carbon reinforced plastics. This part was introduced with the Mercedes SL 65 AMG and has brought about a con-siderable weight reduction with respect to the previous version of the trunk lid.

Prior to the measurement, the test speci-men was mounted with rubber bungee cords in a free-free state. A shaker was installed to excite the structure, with a force sensor glued to a fixed position and connected to the shaker.

A grid of 1,000 points was imported and used for the measurement, extract-ed from a coarsened FE mesh. A multi-sine pseudo random signal, together with a rectangular window, was used at a frequency bandwidth of 200 Hz and a frequency resolution of 0.5 Hz, using 10 complex averages. Fig. 6 shows the amplitude of the transfer function in the z direction (velocity/force) and the imaginary part of the transfer function (z acceleration/force) at the driving

point location. Figures 7 and 8 show the calculated simulation result at 42.5 Hz and the measured deflection shape at 45 Hz.

After modal extraction, MAC values are recalculated to assess the similarity of the results from measurement and simulation. The MAC matrix for these results is of outstanding quality. The first 14 modes were found in excellent agreement with the FEA results.

Fig. 4: MAC matrix between modes from simulation and measurement of the closed Z profile.

Ref.Mode

Ref.Freq.

WorkMode

WorkFreq.

MAC Freq. %Error

1 178,0 1 180,4 0,980 1,4

2 318,5 2 329,8 0,982 3,6

3 473,6 3 482,4 0,976 1,9

4 656,8 4 665,5 0,932 1,3

6 840,1 5 834,4 0,854 –0,7

7 903,7 6 904,8 0,946 0,1

Fig. 3: Modes from measurement result (left) and modes from FE analysis (right) of the closed Z profile.

17

Results and Outlook

The Polytec 3-D Scanning Laser Vibro-meter enables seamless integration of test-based dynamic models into the CAE development workflow. Since with this approach the 3-D coordinates of the FE model and the test geometry are identical by definition, there was no need for fur-ther geometric correlation. All simulated mode shapes could be clearly identified in the resulting deflection shapes. Data quality and grid density were extraordi-nary, with no mass-load effects and no errors resulting from inaccurate Euler angles. The model correlation could be extended towards even higher frequen-cies. The method has proven to deliver datasets suitable for a more efficient FE model updating process in a consider-ably shorter time and with significantlybetter quality compared to traditional approaches.

Fig. 5: Optical vibration measurement on a trunk lid.

Fig. 6: Amplitude of the transfer function in the z direction velocity/force (above) and the imaginary part of the transfer function z acceleration/force (below).

Fig. 7: Simulated mode at 42.5 Hz. Fig. 8: Measured deflection shape at 45 Hz.

Authors · ContactDr. Kamal Idrisi, RD/RMC, Daimler AGkamal.idrisi@daimler.com

Eric Winkler, Dr. Jochen Schell, Polytec GmbHoms@polytec.de

This contribution is based on a presenta- tion delivered at the EMAUG Conference (European Modal Analysis Users Group), Ingolstadt, Germany, March 10–11, 2011.

18

Material research

Market Leader Trusts in Polytec

“Our good relation-ship has always been appreciated”

19

Arnold Schneider, one of Herrmann’s CEOs, adds: “Both companies have so much in common: high tech products, world market leaders in our respective fields, as well as continuity and persis-tence in our profession. Polytec’s tech-nology is fascinating, so is ours.”

Herrmann is well known for machines that use ultrasonic vibrations to weldplastics together. This technology is being used for example to produce car door coverings, food packaging or diapers. So be aware that the next drinking pouch or coffee pad you use might have been produced with Herrmann technology.

How does ultrasonic welding work? Titan tools, the so-called sonotrodes, are brought to self-resonant oscillation. The heat generated by friction is used for the welding. The molecular structure is be-ing broken and reconnected. The welded region is hardly visible and absolutely leakproof. “An additional advantage is that no hazardous glues have to be used” says Ulrich Vogler, product development manager at Herrmann.

Vibrometers from Polytec help Herrmann ensure that the sonotrodes vibrate cor-rectl y: “Nearly every welding tool is unique and there are always new require-ments: disturbing resonances to address, deflection shapes that are not as planned, tools that don’t behave as predicted be cause the materials used have different vibration characteristics”, explains Vogler.

The deflection shapes that are captured with the PSV help Herrmann optimize the vibrational characteristics of the sono-trodes. The scanning vibrometer checks every sonotrode that leaves Herrmann as well as every sonotrode that arrives for inspection. Only the non-contact meas-urement tools from Polytec allow this kind of quality control. Vogler explains: “With this control we can be sure that the tools leaving our house do their job for the customer. With the PSV they can be sure that their machines produce reliably.”

The ultrasonics specialist uses the vibro -meter not only on the production floor but more recently in development. Three vibrometers are permanently in action. Ò

Both companies have so many

parallels that one might speak

of them as twins. Herrmann is

situated in Karlsbad, only a few

kilometers from Polytec’s head-

quarters in Waldbronn. In addi-

tion, the ultraonic specialists

have been in business just 6

years longer than Polytec and

employ 260 worldwide.

Herrmann’s product development manager Ulrich Vogler in front of PSV-equipped test stand.

20

Material research

Vogler confesses: “My dream would be to own a 3-D scanning system from Polytec. With this I could measure and document vibrations in all directions at the same time.”

Herrmann has been Polytec’s customer for 12 years. The ultrasonics specialists particularly appreciate Polytec’s flex-ibility as well as the willingness to re-spect the individual demands of the customer. “You customized a lot for us. That brought us away from the stan-dard,” tells Schneider. Vogler adds: “We benefited from our investment in modern measurement technology. It took us technologically a step ahead.”

Before the PSV, quality control took half an hour. Today it only takes less than a minute. The customer benefits from shorter delivery times.

An additional commonality that Schneider appreciates is the good intercompany relationship. He reveals with a smile: “We have always got along well and that has always been appreciated – no matter who we had contact with at Polytec.”

Everything ok? Quality control of a sonotrode using a scanning vibrometer.

Herrmann Ultraschalltechnik GmbH & Co.KGHigh-tech engineering company for ultrasound welding machines and modules

Managing director: Walter und Thomas Herrmann, Arnold Schneider

Sales: ca. 40 Mio. €

Employees: 250 worldwide

Export share: 55%

21

Simulation

MAN Diesel & Turbo SE is the world’s leading provider of large-

bore diesel engines and turbomachinery for marine and statio-

nary applications. It designs two-stroke and four-stroke engines,

gas and steam turbines as well as compressors. The product

range is rounded off by turbochargers, propellers, gas engines and

chemical reactors. MAN Diesel & Turbo’s range of goods includes

marine propulsion systems, turbomachinery units and turnkey

power plants. Ò

Harald MittelhammerTurbocharger Engineer-ing Validation MAN Diesel & Turbo SE.

MAN Counts on Polytec

“Polytec has Competence in Laser Measurement Technology”

22

Simulation

We spoke to Harald Mittelhammer who works for the validation

group of the turbo charger development department about his work

with the Scanning Vibrometer and his experiences with Polytec.

23

What is your general impression of Polytec?

What is really special about Polytec is the fast response to addressing any pro-blems. No competitor can keep up with that. Polytec is very proficient in the field of laser-based measurement technology.

Do you see any opportunities for using more measurement technology from Polytec at MAN Diesel & Turbo SE? If yes: what are your plans?

We are planning to use experimental modal analysis not only on parts but also on complete turbochargers. We have also started to use single point vibrometers for monitoring running motors.

Mr. Mittelhammer, we thank you for the interview.

MAN Diesel & Turbo SE is the world’s leading provider of large-bore diesel engines and turbomachinery

Sales: 3,780 Mio. €

Employees: ca. 15,000 worldwide

Hammer excitation and vibration measurement on a compressor wheel and a turbine blade.

Mr. Mittelhammer, what is your job at MAN Diesel & Turbo SE?

My job is to validate turbocharger components.

What vibrometer from Polytec are you using?

We use the PSV-400 running software version 8.8 and are in the process of updating to version 9 as part of a hard-ware upgrade. Expanding from 4 to 8 acquisition channels will allow us to simultaneously acquire strain gage signals during a single PSV scan.

Can you briefly explain your appli-ca tion for our vibrometer?

In simple terms: We use the PSV for our FE models. The validation group collects data so that modal analysis can be per-formed for compressor wheels and turbo-charger turbines. These experimental results are then used to adjust the para-meters needed to calculate the FE data.

How would you describe the quality standards at MAN Diesel & Turbo SE? What would happen if those standards aren’t met?

We would lose our ISO 9001 certificate. Aside from that, damage would be un-avoidable if the required standards aren’t met, and that is always connected with higher costs.

How do Polytec’s vibrometers help you meet the required quality standards?

For us the key to success is the non-con-tact measurement technology for rotatio-nally symmetric parts combined with fast scanning of many measurement points.

How do you benefit from using non-contact measurement technology?

We take advantage of the fast setup, high resolution and last but not least: the very high sensitivity.

How did you measure vibrations before and what difficulties did you face?

Before the PSV became available we used strain gages to measure vibrations. The low sensitivity and low energy input pre-vented good measurement results. Aside from that, the contact nature of strain gages influenced the measured structure. Only a limited number of measurement points were possible because the gages tended to stiffen the structure.

You attended our 12th vibrometer user conference, presented your appli-cation and got in touch with other Polytec users. Would you recommend the event?

As long as my calendar allows, the event will be a firm committment. The wide range of applications is especially inter-est ing for me and I recommend the event to everyone concerned with vibrations.

24

A portable high end workstation controls the basic functions. It includes a 50 kHz bandwidth data acquisition system for the vibrometer and reference channels, an optional signal generator and an avail-able geometry scan unit controlled via the digital VibroLink interface. VibroLink is a simple GBit Ethernet connection that avoids tedious setup procedures and allows the user to independently control his or her PSV system from up to 100 m away while still enjoying the benefits of HD video from the scanning head.

ng the benefits of anning head.

Product News

In the Most Compact Format

PSV Scanning VibrometerGrab the scanning head, tripod, front-end and notebook,

and away you go to the next measurement site. Thanks to

the new compact PSV-500-NB Scanning Vibrometer, there’s

no need to leave behind a powerful full-field vibration

measurement system.

25

PSV-A-550 Remote Control

Setting up a scanning vibrometer measurement with the operator stand- ing close to the test object definitely has its advantages, especially when com-plex geometries such as narrow edges or piping are present. The new remote control available for PSV-500 Scanning Vibrometers allows you to position meas-urement points precisely with the tip of your finger. The PSV-A-550 is based on a Windows Surface RT tablet computer running the “PSV Commander” app. Controlling the laser position, as well as setting and deleting measurement points, is achieved with standard gestures. The video image is also transferred to the tab-let computer as a further aid to the set-up procedure. While this option is beneficial for all users, PSV-500-3D users will espe-cially enjoy using it to achieve precise 3-D alignments. The PSV-A-550 remote con-trol is available either as an option or for subsequent installation bundled with a pre-configured WLAN router for the PSV system cabinet.

Contact · More InfoFor more information on our ScanningVibrometers and their accessories visit: www.polytec.com/psv

Tripod System for PSV-3D

In order to avoid having to repeat the 3-D alignment each time PSV-3D scan-ning heads are moved, the relative posi-tion of the three heads with respect to one another should ideally not change. The PSV-A-T51 motorized tripod system guarantees this as different regions of the structure are accessed, improving productivity and reducing any possibili-ty of human error. This newly designed tool replaces the PSV-A-T31 tripod sys -tem and adds a new dimension of flexi-bility to the PSV-3D. Measurement posi-tions can easily be changed with the aid of 3 independent motors. Intelligent kinematics helps avoid additional sup-port ing arms and reduces the chance of overturning. The now smaller foot-print saves space in your lab.

PSV

Setme inghasplexor pconVibureyoua WrunConsettis avidelet cprofor cialaligtrolsubpresyst

PSV-A-525 Protective Window

Precision optics and dust do not go well together. But using a scanning laser Doppler vibrometer is of such a great advantage that there is often pressure to operate PSVs in unfriendly environments. The PSV-A-525 protective window seals the camera and scanner port with a layer of professional optical grade anti-reflec-tion coated glass. Spray and dust are kept away from the sensitive optics and at the same time reduce scanning mirror excitation with any high sound pressure levels that may exist. This new accessory is exclusively available for PSV-500 sys-tems.

26

Product News

visualize motion with sub-nanometer amplitudes? How do you test the function parameters of MEMS that are electrically inaccessible, but which might influence the mechanical motion? All of these ques-tions can be answered easily, quickly and reliably with the help of optical measure-ment methods such as Laser Doppler Vibrometry. And fresh possibilities can now be realized with Polytec’s new MSA-100-3D Micro System Analyzer.

The MSA-100-3D enables real-time 3-D vibration parameter measurement of microscopic objects with unprecedented accuracy. To achieve this, a single laser beam is focused onto the structure to be measured and the scattered light is evalu-ated in 3 different spatial directions. The three-dimensional motion of the object is determined from the Doppler frequency

shifts of the scattered light. What is so innovative about this new measurement instrument is its ability to measure in-plane motion with picometer (pm) reso-lution. Since most MEMS have moving elements with predominantly in-plane motion, this new instrument satisfies for the first time an important measurement requirement of the user community.

The new system is compatible with stand-ard probe stations and can therefore be applied directly to measurements on the wafer level, even under vacuum condi-tions.

3-D Vibration Measurement on Micro Structures

MSA-100-3D Micro System Analyzer

Certified Accuracy

LSV-MID

Products that are sold by length have to be measured on calibrated machines. In these cases it is important that the meas-urements are accurate and the data are integer and safe. In the European Com-munity this is regulated by the European Measurement Instruments Directive MID 2004/22/EC.

Polytec developed the LSV-1000MID in compliance with these regulations. It contains a sensor head and a controller in the form of an industrial PC. The measurements are saved for at least 90 days and are available for verification. An open Ethernet protocol allows the easy and comfort able integration of the system into the network structure.

How does a development engineer cha-racterize the motion dynamics of Micro Electro Mechanical Systems (MEMS) such as gyroscopes, accelerometers or other micro devices with moving mechanical components? How do you measure and

More Infowww.polytec.com/microsystems

More Infowww.polytec.com/lsv

Vibration Measurement at Right Angles to the Beam Direction

IPV-100 In-Plane Vibrometer

In-Plane vibrometers measure axial mo tion from the side. They are employ-ed when the line of sight is blocked in the direction of motion. In-Plane vibro-meters are employed for example in the development and quality assurance of ultrasonic tools and HDD sliders, and are an indispensable tool for efficient analysis of belt drives and the effects of slippage. Also, piston-like movements of tools can be measured under opera-tional conditions.

The new IPV-100 features a large 250 kHz bandwidth combined with high velocity resolution, which enables measurement of even the smallest

vibrations. This new generation of instru-ments also offers improved measure-ment performance on difficult – e.g. dark and dull – surfaces.

Vibration Measurement Now Easier and Faster

OFV-5000 Modular VibrometerThe modular OFV-5000 controller, due to its performance and versatility, is a key component of Polytec’s best selling laser vibrometers. Operating over a wide fre-quency bandwidth from DC to 24 MHz, it is suited for many different applications – from research labs to industrial produc-tion lines.

This well-proven laser vibrometer con-troller is now equipped with a large 7”

color touch screen and a new, carefully designed interactive concept to create a great user experience. Therefore, con-figuring the vibrometer system is now even more intuitive and easy for experi-enced and new users alike.

In terms of technical specifications, the OFV-5000 vibrometer controller is fully compatible with its predecessor and its established sensor heads.

27

More Infowww.polytec.com/inplane

More Infowww.polytec.com/ofv5000

Events

Advancing Measurements by Light

Trade Shows and ConferencesDate Event Location

Nov 18 – 20, 2013 Eastern Analytical Symposium & Exposition Somerset, NJ

Nov 18 – 20, 2013 Eastern Analytical Symposium & Exposition Somerset, NJ

Nov 20 – 21, 2013 International Meeting on Optical Measurement Techniques and Industrial Applications

Shell Rijswijk, Netherlands

Dec 10 – 13, 2013 ASTA CSS 2013 & Seed Expo Chicago, IL

Jan 26 – 30, 2014 MEMS 2014 San Francisco, CA

Feb 3 – 6, 2014 IMAC XXXII Orlando, FL

Mar 12 – 13, 2014 Smart Structures and Materials – NDE San Diego, CA

www.polytec.comTech

nica

l sp

ecifi

catio

ns a

re s

ubje

ct t

o ch

ange

with

out

notic

e. O

M_I

nFoc

us_2

013_

5000

_E

Polytec GmbH (Germany)Polytec-Platz 1-776337 WaldbronnTel. + 49 7243 604-0info@polytec.de

Polytec France S.A.S.Bâtiment Orion – 1er étage39, rue Louveau92320 ChâtillonTel. +33 1 496569-00info@polytec.fr

Polytec Ltd.(Great Britain)Lambda House, Batford Mill Harpenden, Herts A L5 5BZTel. + 44 1582 711670info@polytec-ltd.co.uk

Polytec Japan Arena Tower, 13th floor3-1-9, Shinyokohama Kohoku-ku, Yokohama-shiKanagawa, 222-0033Tel. +81 45 478-6980info@polytec.co.jp

Polytec, Inc. (USA) North American Headquarters16400 Bake ParkwaySuites 150 & 200Irvine, CA 92618Tel. +1 949 943-3033info@polytec.com

Central Office1046 Baker RoadDexter, MI 48130Tel. +1 734 253-9428

East Coast Office25 South Street, Suite AHopkinton, MA 01748Tel. +1 508 417-1040

Polytec South-East Asia Pte LtdBlk 4010 Ang Mo Kio Ave 10#06-06 TechPlace 1Singapore 569626Tel. +65 6451 0886info@polytec-sea.com Imprint

Polytec InFocus · Optical Measurement SolutionsIssue 1/2013 – ISSN 1864-9203 · Copyright © Polytec GmbH, 2013Polytec GmbH · Polytec-Platz 1-7 · D-76337 Waldbronn, Germany

CEO/Publisher: Dr. Hans-Lothar PaschEditorial Staff: Dr. Philipp HassingerProduction: Regelmann KommunikationImages courtesy of the authors unless otherwise specified.

Polytec Web Academy Date Topic

Nov 7, 2013 New MSA-100-3D Micro System Analyzer for 3-D-Vibration Measurement on Microscopic Structures

Jan 22, 2014 Improving Performance of MEMS Designs Using Dynamic Characterization

Feb 4, 2014 Introduction to Non-Contact Vibration Measurement

Feb 5, 2014 Structural Health Monitoring of Bridges, Buildings and Industrial Plant with New Ultra-Long-Range Vibrometer

Feb 6, 2014 Characterize, Analyze and Validate Surface Metrology with Innovative, High Precision, Optical Surface Profiling Systems

Mar 5, 2014 Improving Performance of MEMS Designs Using Dynamic Characterization

All Webinars start at 11:00 PST and last one hour. Register at www.polytec.com/us/events/web-academy/

Always at Your ServicePolytec offers more than vibration and topography instruments – a variety of engineering services, sys tem rentals, user trainings, hardware maintenance and calibration services guarantee the best solution to your challenge.

For more information call us or visit us online.

� + � � �