Session: Research Posters

Paper Number: 167145

Delineating the Effects of Various Internal and External Paraments of Homogeneous and Composite Nonlinear Viscoelastic Materials Using Experimental Testing 

In this work, we study the mechanics of laboratory samples made of viscoelastic polydimethylsiloxane (PDMS) material under a variety of rate dependent loading condition and different preparation techniques such as curing agents and curing temperatures. We also study the effect of existence of porosity on the strength and response of this material and the enhancements in the mechanical response due to the addition of fiber reinforcements into a PDMS matrix. The investigations are primarily performed experimentally with a routine involving, preparation of samples, experimental testing, and elucidating the effects of different criteria to delineate the phenomena observed from mechanical testing. Viscoelastic materials have the property to vary their mechanical response to loading conditions depending on the rate at which they are loaded. This property is exhibited due to the dual behavior of such materials as both a solid and a fluid. The viscous property of these materials due to the fluid-like characteristics makes them dependent on the velocity gradient of deformation, which directly relates to the rate dependency of loading while the solid-like characteristics of these material define their stiffness and frequency response behavior. The viscoelastic PDMS material chosen in this study also exhibits material nonlinearity, which further adds complications to the constitutive modeling of these materials. In this work, the material Sylgard 184, which is a slow room temperature cure PDMS material is used to create the test samples. Mechanical properties of this material have been studied and presented extensively in the literature. However, critical scrutiny of factors such as the effect of presence of porosity due to the inclusion of air cavities during preparation, and changes in mechanical response due to the additional of linear elastic fiber reinforcement into a PDMS matrix have not received considerable attention in the literature. Test specimens of viscoelastic PDMS are created under different curing temperature conditions and its effect on the mechanical properties is evaluated by running experimental tensile and compressive tests on these samples using standard ASTM tests. Also, it is hypothesized that the presence of air cavities creates pockets of compressible material within the PDMS sample resulting in enhancement in absorption of impact energies. To test this hypothesis, porous sample are created and tested under dynamic impact loads. The final study performed is to observe the changes in the mechanical response of the nonlinear viscoelastic PDMS material by addition of linear elastic carbon fibers in it, which creates a directional transversely isotropic PDMS composite. Interaction of the nonlinear elastic matrix with the linear elastic fiber creates an interesting deformation behavior at the fiber-matrix interface, which is studied experimentally in this work.  

Presenting Author: Caleb Pruitt Marshall University

Presenting Author Biography: Clayton Bloss is a graduate student at the Mechanical and Industrial Engineering Department at Marshall University pursuing a MS degree in Mechanical Engineering. Prior to graduate school, he received a BS in Mechanical Engineering from Marshall University.

Authors:

Caleb Pruitt Marshall University
Clayton Bloss Marshall University
Arka Chattopadhyay Marshall University