Imperial College London
Alternate

Dr Mazdak Ghajari

Faculty of Engineering, Dyson School of Design Engineering

Reader in Brain Biomechanics
 
 
 
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Contact

 

+44 (0)20 7594 9236m.ghajari Website

 
 
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Location

 

Dyson BuildingSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Abayazid:2020:10.1016/j.addma.2020.101160,
author = {Abayazid, F and Ghajari, M},
doi = {10.1016/j.addma.2020.101160},
journal = {Additive Manufacturing},
title = {Material characterisation of additively manufactured elastomers at different strain rates and build orientations},
url = {http://dx.doi.org/10.1016/j.addma.2020.101160},
volume = {33},
year = {2020}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - Material jetting, particularly PolyJet technology, is an additive manufacturing (AM) process which has introduced novel flexible elastomers used in bio-inspired soft robots, compliant structures and dampers. Finite Element Analysis (FEA) is a key tool for the development of such applications, which requires comprehensive material characterisation utilising advanced material models. However, in contrast to conventional rubbers, PolyJet elastomers have been less explored leading to a few material models with various limitations in fidelity. Therefore, one aim of this study was to characterise the mechanical response of the latest PolyJet elastomers, Agilus30 (A30) and Tango+ (T+), under large strain tension-compression and time-dependent high-frequency/relaxation loadings. Another aim was to calibrate a visco-hyperelastic material model to accurately predict these responses. Tensile, compressive, cyclic, dynamic mechanical analysis (DMA) and stress relaxation tests were carried out on pristine A30 and T+ samples. Quasi-static tension-compression tests were used to calibrate a 3-term Ogden hyperelastic model. Stress relaxation and DMA results were combined to determine the constants of a 5-term Prony series across a large window of relaxation time (10 μs–100 s). A numerical time-stepping scheme was employed to predict the visco-hyperelastic response of the 3D-printed elastomers at large strains and different strain rates. In addition, the anisotropy in the elastomers, which stemmed from build orientation, was explored. Highly nonlinear stress-strain relationships were observed in both elastomers, with a strong dependency on strain rate. Relaxation tests revealed that A30 and T+ elastomers relax to 50 % and 70 % of their peak stress values respectively in less than 20 s. The effect of orientation on the loading response was most pronounced with prints along the Z-direction, particularly at large strains and lower strain rates. Moreover, the visco-hyperelastic m
AU  - Abayazid,F
AU  - Ghajari,M
DO  - 10.1016/j.addma.2020.101160
PY  - 2020///
SN  - 2214-8604
TI  - Material characterisation of additively manufactured elastomers at different strain rates and build orientations
T2  - Additive Manufacturing
UR  - http://dx.doi.org/10.1016/j.addma.2020.101160
UR  - http://hdl.handle.net/10044/1/78140
VL  - 33
ER  -
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