Stress-Strain Behaviour of Dielectric Elastomer for Actuators

2015 ◽  
Vol 789-790 ◽  
pp. 837-841 ◽  
Author(s):  
R.K. Sahu ◽  
K. Patra ◽  
S. Bhaumik ◽  
A.K. Pandey ◽  
D.K. Setua
Keyword(s):  
Strain Rate ◽  
Maximum Stress ◽  
Dielectric Elastomer ◽  
Cyclic Softening ◽  
Hysteresis Loss ◽  
Commercial Application ◽  
Stress Strain ◽  
Rate Dependent ◽  
Nonlinear Stress ◽  
Loading Case

Dielectric elastomer (DE) is gaining importance for potential strategic and commercial application as actuators. This paper reports the experimental investigation on different mechanical phenomena at large deformation of a commercially available acrylic dielectric elastomer material, VHB 4910 (3M) which is widely used for dielectric elastomer actuator (DEA) research. Attempts are made for accurate and precise experimental determination of nonlinear stress-strain, strain rate dependent hysteresis behaviour and cyclic softening of this material. It is observed that with the increase in strain rate maximum stress at a particular strain increases whereas hysteresis loss decreases. In the cyclic loading case after a particular number of cycles almost the hysteresis loss and maximum stress becomes constant. These experimental results are likely to be interesting for the designers for proper designing and characterization of the actuators fabricated with this material.

scholarly journals Identification of the LLDPE Constitutive Material Model for Energy Absorption in Impact Applications

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1537
Author(s):  
Luděk Hynčík ◽  
Petra Kochová ◽  
Jan Špička ◽  
Tomasz Bońkowski ◽  
Robert Cimrman ◽  
...  
Keyword(s):  
Strain Rate ◽  
Material Model ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Stress Strain ◽  
Rate Dependent ◽  
Constitutive Material Model ◽  
Principal Directions ◽  
Constitutive Material

Current industrial trends bring new challenges in energy absorbing systems. Polymer materials as the traditional packaging materials seem to be promising due to their low weight, structure, and production price. Based on the review, the linear low-density polyethylene (LLDPE) material was identified as the most promising material for absorbing impact energy. The current paper addresses the identification of the material parameters and the development of a constitutive material model to be used in future designs by virtual prototyping. The paper deals with the experimental measurement of the stress-strain relations of linear low-density polyethylene under static and dynamic loading. The quasi-static measurement was realized in two perpendicular principal directions and was supplemented by a test measurement in the 45° direction, i.e., exactly between the principal directions. The quasi-static stress-strain curves were analyzed as an initial step for dynamic strain rate-dependent material behavior. The dynamic response was tested in a drop tower using a spherical impactor hitting a flat material multi-layered specimen at two different energy levels. The strain rate-dependent material model was identified by optimizing the static material response obtained in the dynamic experiments. The material model was validated by the virtual reconstruction of the experiments and by comparing the numerical results to the experimental ones.

Strain-Rate-Dependent Stress-Strain Curves for 304 Stainless Steels in Wide Range of Strain Rate

2019 ◽  
Vol 2019 (0) ◽  
pp. OS1510
Author(s):  
Junmin SEO ◽  
Hayato TOKUNAGA ◽  
Tomohisa KUMAGAI ◽  
Yasufumi MIURA ◽  
Yunjae KIM
Keyword(s):  
Strain Rate ◽  
Stainless Steels ◽  
Stress Strain ◽  
Rate Dependent ◽  
Wide Range

scholarly journals Identification of LLDPE Constitutive Material Model for Energy Absorption in Impact Applications

2021 ◽  
Author(s):  
Luděk Hynčík ◽  
Petra Kochová ◽  
Jan Špička ◽  
Tomasz Bońkowski ◽  
Robert Cimrman ◽  
...  
Keyword(s):  
Strain Rate ◽  
Material Model ◽  
Low Density Polyethylene ◽  
Low Density ◽  
Linear Low Density Polyethylene ◽  
Stress Strain ◽  
Rate Dependent ◽  
Constitutive Material Model ◽  
Principal Directions ◽  
Constitutive Material

Current industrial trends bring new challenges in energy absorbing systems. Polymer materials as the traditional packaging material seem to be promising due to their low weight, structure and production price. Based on the review, the linear low-density polyethylene material was identified as the most promising material for absorbing impact energy. The current paper addresses the identification of the material parameters and the development of a Constitutive material model to be used in future design by virtual prototyping. The paper deals with the experimental measurement of the stress-strain relations of the linear low-density polyethylene under static and dynamic loading. The quasi-static measurement is realized in two perpendicular principal directions and is supplemented by a test measurement in the 45 degrees direction, i.e. exactly between the principal directions. The quasi-static stress-strain curves are analyzed as an initial step for dynamic strain rate dependent material behavior. The dynamic response is tested in the drop tower using a spherical impactor hitting the flat material multi-layered specimen at two different energy levels. The strain rate dependent material model is identified by optimizing the static material response obtained in the dynamic experiments. The material model is validated by the virtual reconstruction of the experiments and by comparing the numerical results to the experimental ones.

The Maximum Stress in Optical Glass Fibers Under Two-Point Bending

2000 ◽  
Vol 123 (1) ◽  
pp. 70-73 ◽  
Author(s):  
Mikio Muraoka
Keyword(s):  
Axial Force ◽  
Maximum Stress ◽  
Optical Glass ◽  
Glass Fibers ◽  
Order Term ◽  
Nonlinear Behavior ◽  
Bending Stress ◽  
Stress Strain ◽  
Nonlinear Stress ◽  
Strain Relationship

The maximum stress in optical glass fibers subjected to two-point bending was evaluated by E. Suhir, “Effect of the Nonlinear Behavior of the Material on Two-Point Bending of Optical Glass Fibers,” ASME Journal of Electronic Packaging, Vol. 114, pp. 246–250, taking into account the shift in the neutral axis due to the nonlinear stress-strain relationship of the materials. However, the resulting distribution of bending stress on the fiber cross-section is not realistic because it produces a nonzero axial force. In the present study, we derive the correct formulas for evaluating the maximum stress under the valid condition that the bending stress does not contribute to the axial force. Moreover, we employ the nonlinear stress-strain relationship containing a third-order term of strain, which is more appropriate for the materials than that utilized by Suhir.

Dynamic Mechanical Behavior of Two Fiber-Reinforced Composites

2012 ◽  
Vol 525-526 ◽  
pp. 261-264
Author(s):  
Y.Z. Guo ◽  
X. Chen ◽  
Xi Yun Wang ◽  
S.G. Tan ◽  
Z. Zeng ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Strain Rate ◽  
Mechanical Behavior ◽  
High Speed ◽  
Split Hopkinson Pressure Bar ◽  
Hopkinson Pressure Bar ◽  
Stress Strain ◽  
Rate Dependent ◽  
Dynamic Loadings ◽  
Axial Splitting

The mechanical behavior of two composites, i.e., CF3031/QY8911 (CQ, hereafter in this paper) and EW100A/BA9916 (EB, hereafter in this paper), under dynamic loadings were carefully studied by using split Hopkinson pressure bar (SHPB) system. The results show that compressive strength of CQ increases with increasing strain-rates, while for EB the compressive strength at strain-rate 1500/s is lower then that at 800/s or 400/s. More interestingly, most of the stress strain curves of both of the two composites are not monotonous but exhibit double-peak shape. To identify this unusual phenominon, a high speed photographic system is introduced. The deformation as well as fracture characteristics of the composites under dynamic loadings were captured. The photoes indicate that two different failure mechanisms work during dynamic fracture process. The first one is axial splitting between the fiber and the matrix and the second one is overall shear. The interficial strength between the fiber and matrix, which is also strain rate dependent, determines the fracture modes and the shape of the stress/strain curves.

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