Dozens of hyperelastic models have been formulated and have been extremely handy in understanding the complex mechanical behavior of materials that exhibit hyperelastic behavior (characterized by large nonlinear elastic deformations that are completely recoverable) such as elastomers, polymers, and even biological tissues. These models are indispensable in the design of complex engineering components such as engine mounts and structural bearings in the automotive and aerospace industries and vibration isolators and shock absorbers in mechanical systems. Particularly, the problem of vibration control in mechanical system dynamics is extremely important and, therefore, knowledge of accurate hyperelastic models facilitates optimum designs and the development of three‐dimensional finite element system dynamics for studying the large and nonlinear deformation behavior. This review work intends to enhance the knowledge of 15 of the most commonly used hyperelastic models and consequently help design engineers and scientists make informed decisions on the right ones to use. For each of the models, expressions for the strain‐energy function and the Cauchy stress for both arbitrary loading assuming compressibility and each of the three loading modes (uniaxial tension, equibiaxial tension, and pure shear) assuming incompressibility are provided. Furthermore, the stress–strain or stress–stretch plots of the model's predictions in each of the loading modes are compared with that of the classical experimental data of Treloar and the coefficient of determination is utilized as a measure of the model's predictive ability. Lastly, a ranking scheme is proposed based on the model's ability to predict each of the loading modes with minimum deviations and the overall coefficient of determination.

The current most favourable material to aerospace industry is the carbon-fibre reinforced polymer composite. Drilling of carbon-fibre reinforced polymer to facilitate holes for component assembly subjects it to myriad of failures with the most severe one being delamination. Thrust force involved during the drilling process has been found to bear a greater responsibility for delamination damage. The elevated forces exceed the interlaminar strength of the composite laminates leading to separation of layers. This work proposes the use of spring dampers as a means of reducing the thrust forces. In order to arrive at a conclusion, two experimental and finite element simulation setups have been done (one with dampers included and the other without). Thrust forces against the drilling depth were recorded for both setups and compared. Scanning electron microscope was used to examine the drilled plates for delamination at entry and exit of the holes. The results show that using dampers does reduce the thrust forces by about 25% and that the forces are higher towards the exit of the hole which explains the elevated push-down delamination. The experimental and finite element simulation results for forces were found to agree reasonably, hence validating the finite element model.

Understanding the drilling-induced damage to carbon fiber-reinforced polymer composites remains the most active research being undertaken in the composite materials world of today. Despite the vast amounts of literature available, the relationship between drilling and damage to the composites has not been fully understood. In this research, a comparative study of different drilling methods including the use of a twist drill, the use of a pilot hole/pre-drilled hole and the use of a step drill on the influence of the hole quality has been accomplished. In order to achieve this comparison, thrust forces have been monitored during drilling experiments where four different feed rates and one spindle speed have been considered. A finite element model has also been included to study delamination damage on the laminates and validate the experimental results. Results show that thrust forces increase with increasing feed rates and that drilling by step drill is the most appropriate method as it records low forces hence minimal delamination damage.

This research work has been aimed at understanding the effects of different fiber orientations and different stacking sequences of composite laminates on their damage during drilling of CFRP/Al stack. Finite element code Abaqus/CAE has been used for the implementation and analysis of the numerical model. Surface-based cohesive behavior available in Abaqus/CAE contact pairs has been used to simulate delamination behavior in the adhesive interfaces. In order to use the Hashin damage criterion (for intra-laminar damage) available in the finite element code, continuum shell elements have been used for laminates. Three stacking sequences each with 24 layers including [0°] ₂₄ , [0°/90°] _12s , and [−45°/90° ₄ /45° ₂ /−45°] _3s have been considered for this study. The display group manager available in Abaqus/CAE visualization module enabled the individual access of the damage in each layer. Two layers both at drill entry and at CFRP/Al interface were used to study peel-up and push-down delamination, respectively. Sequence [0°] ₂₄ was found to have the largest damaged in both entry and interfaces, while sequence [−45°/90° ₄ /45° ₂ /−45°] _3s was found to show better resistance to delamination damage.

Fiber-reinforced polymer composites are increasingly utilized in applications where both the weight and the strength of the components are critical as in the aerospace industry. However, the full utilization of these materials could be hindered by the weak out-of-plane properties which precipitate delamination. Carbon nanotubes (CNTs) have recently gained massive interests due to its superior mechanical properties, which are excellent for improving the fiber/matrix interface. The current study considered two specimens of glass fiber-reinforced polymer composites (with and without CNT buckypaper) and subjected them to two tests, namely interlaminar shear strength and helical milling tests. Results show that the CNTs increase the interlaminar strength of the laminates by about 25% and the images of the machined parts reveal a separation of layers (delamination) on the specimens without CNT while on the other hand uncovering a relatively good quality surface and a good fiber/matrix/CNT interface for the specimens with CNT.