For viscoelastic materials, the relationship between stress and strain depends on time, where the applied strain (or stress) can be expressed as a step function of time. In the present work, we investigated two temporary effects in the response of viscoelastic materials when a given strain is applied and then removed. The application of strain causes a stress response over time, also known as relaxation. By contrast, recovery is the response that occurs following the removal of an applied stress or strain. Both stress and relaxation constitute transient stages of a viscoelastic material exposed to a permanent force. In the current work, we performed several experimental tests to record the recovery in response to the total or partial removal of the strain. By observing and analyzing the mechanical response of the material to strain, we deduced that recovery is a procedure not only related to creep but also to relaxation. Hence, we created a model that simulates the behavior of viscoelastic materials, contributing to the prediction of relevant results concerning different conditions.

Elastomers exhibit a complex response to high-strain-rate deformation due to their viscoelastic behaviour. Environmental conditions highly impact this behaviour, especially when both temperature and humidity change. In several applications where elastomers are used, the quantity of real humidity might vary, especially when the temperature is elevated. In the current research, elastomeric materials were subjected to high-strain-rate compression in various elevated and lowered (cold) temperatures. Different humidity levels were applied at room and elevated temperatures to analyze the behaviour of rubbers in dry and moist conditions. Results showed that the mechanical behaviour of rubbers is highly affected by any environmental change. In particular, the impact caused by humidity variations is relative to their ability to absorb or repel water on their surface.

This study aims to model and validate the influence of temperature on the stress relaxation of silicone rubber, numerically. The stress relaxation tests were performed at a constant strain level using a constant crosshead speed at the below ambient temperatures. The Time-Temperature superposition, The Williams-Landed-Ferry (WLF), was applied to describe temperature and stress relaxation of Silicone rubber. First, the master curve was obtained, and then the WLF coefficients were determined by curve fitting technique. This study demonstrated that temperature affected the stress relaxation and stress relaxation decreases with decreasing temperature. Also, FEM results validated the experimental results.

Simulating the mechanical behavior of rubbers is widely performed with hyperelastic material models by determining their parameters. Traditionally, several loading modes, namely uniaxial tensile, planar equibiaxial, and volumetric, are considered to identify hyperelastic material models. This procedure is mainly used to determine hyperelastic material parameters accurately. On the contrary, using reverse engineering approaches, iterative finite element analyses, artificial neural networks, and virtual field methods to identify hyperelastic material parameters can provide accurate results that require no coupon material testing. In the current study, hyperelastic material parameters of selected rubbers (neoprene, silicone, and natural rubbers) were determined using an artificial neural network (ANN) model. Finite element analyses of O-ring tension and O-ring compression were simulated to create a data set to train the ANN model. Then, the ANN model was employed to identify the hyperelastic material parameters of the selected rubbers. Our study demonstrated that hyperelastic material parameters of any rubbers could be obtained directly from component experimental data without performing coupon tests.

This study aims to experimentally compare the elasto-mechanical behaviors of ethylene propylene diene monomer rubber (EPDM), neoprene rubber, silicone rubber, and natural rubber. Rubbers were tested under uniaxial, equibiaxial, and planar loading for five different samples of each material, and the average values have been calculated. Based on the experimental results, a rubber identification was performed by using different rubber models such as Ogden, Mooney-Rivlin, etc. presented in the literature. The result of this study demonstrated that the EPDM rubber showed the highest stress value compared to the other rubbers, silicone rubber, and natural rubber showed similar behavior. Moreover, Neoprene rubber showed the lowest stress value.