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VSL FRICTION DAMPER BLADE TEST

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MOKPO BRIDGE

VSL FRICTION DAMPER

BLADE TEST PROCEDURE

HNS

Rev. 0

1 APRIL 2010

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VSL FRICTION DAMPER BLADE TEST

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Introduction of spring blade testThe aim of this test is to validate the behaviour of the spring blade ring by

measurement of their displacement. In addition, the exact value of the blade stiffnesswill be measured, which value becoming the installation stiffness parameter fordamper installation on site. In each project, one blade should be tested for each typeof friction damper.

Force application on site

Test sampleThe following test can be done on 1 set of spring blade ring (i.e. a quarter of the

damper, including support system) placed on its ring blade support, see followingdrawings:

Equipment for testThe following list of equipment is required (not exhaustive):

Testing support for dampers

System for force application (depending on chosen option)

Single blade damper

Sample to be tested

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Equipment for force measurement (calibrated strain gauge, or oilpressure gauge if an hydraulic system is used)

Equipment for displacement measurement (sensor)

Principle of the test:The set of wing preassembled is fixed on a fixed support. It is important to use

the elements that will be used for fixation on site (ring blade support, distance plate,covering plate). An effort is applied at the friction pad location.

Test using pressing jack

Jack used fordamperinstallation

Suggestion formeasurement locations

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Results interpretationThe measurements will be done regularly on specific points see other

suggestions below:

Two points of measurement (points A and B).

A is the measure of sensor A, located at the distance X A from the padcentre.

B is the measure of sensor B, located at the distance X B from the padcentre.

Formula for blade deflexion: B A

B B A A

X X

X X

+

+=

Formula for blade inclination ( ) B A

A B

X X +

=

tan

Test procedure The sample is submitted to a varying effort, which extreme value

corresponds to the force under maximal service deflection as defined by the

design. This force is applied in a certain number of steps (10 for instance). During each step, the force and the deflection are measured and recorded.

Once this limit force value is reached, the blade is released. The finalposition (shall be zero if no plastic deformation has occurred) is carefullynoted.

The measurement sensors are reset to zero, and the same procedure isreapplied 2 additional times.

If the result table is recorded in an excel file, the curve can be fitted usingexcel graph tools, as a linear curve crossing the origin. The stiffness

coefficient is thus determined, as well as the inclination ratio.

Distances tobe noted

Two measurementpoints

Contact surface

Force B

AX A

XB

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Example of test results

Record summary table

Stiffness diagram of spring blade