Development of drop tower experimental facility Individual poster of Adrian Azorin Albero Teammates: David Andrés, Hugo Gallet, Agnieszka Krupinska, Hakim Masyhur, Aurélien Royer, Ibai Unanue Supervisors: Dr James Campbell Dr Tom de Vuyst

Technical contributions

External frame load case analysis

FE modelling of indentation test

MSc Advanced Lightweight Structures and Impact 2013-2014 Group Design Project

Offset 𝑑𝑑 of 𝟏𝟏.𝟗𝟗𝟗𝟗𝟗𝟗 assumed at the point of impact 𝑅𝑅𝑅𝑅 = 𝟏𝟏.𝟔𝟔𝟔𝟔

• Design of the frame, shafts and bearings

• FEA: Indentation test analysis (High weight impact)

• FEA: Study of the operating range when the sample is located at the centre

Equivalent static load of 𝟖𝟖𝟖𝟖𝟖𝟖𝟖𝟖 applied on the trolley

𝑀𝑀 = 𝟏𝟏𝟏𝟏𝟏𝟏𝟖𝟖𝟖𝟖𝟗𝟗 (Applied on the bearings)

Buckling analysis Objective: Estimate the

buckling load of the beams attached to the shafts assuming imperfections 𝒇𝒇𝒏𝒏 (MPa) 130 𝑬𝑬 (GPa) 72 𝟗𝟗 (-) 20 𝑨𝑨 (m2) 0.00183 𝑰𝑰𝒙𝒙𝒙𝒙 (m4) 124.4 x 10-8 𝑳𝑳 (m) 3 𝒛𝒛𝟗𝟗𝒎𝒎𝒙𝒙 (m) 0.04 ESDU 01.01.01 𝑷𝑷𝟗𝟗𝒄𝒄 = 𝟏𝟏𝟔𝟔𝟖𝟖.𝟗𝟗𝟗𝟗𝟏𝟏𝟖𝟖𝟖𝟖

Support frame Sample plate

Hemispherical indenter

• FS=0.3 Indenter-Plate • FS=0.2 Support Frame-Plate

Dry conditions assumed:

FE Results for dry conditions (Friction) Force (kN) Deflection (mm) Energy (J)

7.72 11.1 54.6

Experimental Results: Force: 9.7 kN, Deflection: 13.1 mm, Energy: 61.9 J [1]

Better FE prediction obtained assuming

dry conditions

FE analysis of crushing tube experiment (lighter trolley with sample at the centre)

40x40mm square hollow tube 0.6mm thick walls

Part RF I-Beam (Trolley) 9.8

Flat plate (Trolley) 7.9 Support plate 41.5 Support frame 51.9 External frame 8.9

Interaction between trolley and shafts through the contact guided cable algorithm used for the mounting modelling

Accelerometer’s data extraction

Accelerometer FE model *ELEMENT_SEATBELT_ACCELEROMETER

Accelerometer

Low-pass filter with a minimum cut-off frequency of 41.84Hz is required in order to extract the fundamental acceleration pulse

[1] Liu B., Villavivencio R., Guedes Soares C. (2013), Shear and tensile failure of thin aluminium plates struck by cylindrical and spherical indenters, Analysis and Design of Marine Structures.

Contact: a.azorinalbero@cranfield.ac.uk

𝑰𝑰𝒙𝒙, 𝑰𝑰𝒚𝒚 (cm4) 124.4 𝝈𝝈𝒚𝒚 (MPa) 110 𝑬𝑬 (GPa) 72

Sample plate: 2mm thickness

5083/H111 aluminium alloy

Support frame: 15mm thickness

2 rectangular steel plates Internal cut-out of 127 x 76.2 mm

Crashworthiness, Impacts and Structural Mechanics Group (CISM)

Beam imperfection assumed: 𝒆𝒆 = 𝟖𝟖.𝟖𝟖𝟖𝟖𝟎𝟎𝟗𝟗

[1]

Operating limit: • Tube thickness: 1.1mm • Peak force: 12kN

No Frame: Independent trolley model

Reason:

Mass: 24.3kg Impact velocity: 4.5m/s K.E.: 250J

Mass: 4.901kg Impact velocity: 5.4m/s K.E.: 71.42J

• FEA: Modelling of indentation test

• FEA: Assembly of the finite elements model with the lighter trolley

• Study of the accelerometer’s data extraction and FE model implementation

Methodology: Define a critical load case at the moment of impact. Identify the most critical point which determines how the frame is sized by drawing free body diagrams for all structural components

Section choice

Objective: Develop and validate a finite elements model to be implemented in the whole tower model for studying the overall structural behaviour of the system when performing this experiment

Objective: Check the design of the drop test tower with the lighter trolley and define the operating range. The table shows the reserve factors obtained when crushing the 0.6mm tube

Objective: Implement an accelerometer FE model in the whole tower model and define a methodology for being able to filter the high frequency content obtained when performing drop tests. These results help calibrate the tower

The accelerometer FE model created was implemented in the whole tower FE model with the lighter trolley. The required low-pass filter was calculated by analysing the results obtained for the crushing tube located at the centre