In this study, we investigate the mechanical behavior of each skin layer, in terms of the nominal stress-strain curve by uniaxial tensile tests using specimens of porcine skin in two forms: dermis containing epidermis, and all three layers. All tests were performed under cyclic loading at the constant strain rate of 10–3 s–1 at ambient temperature. To measure the precise initial cross-sectional areas of each layer, the thickness of each skin layer was quantified by counting the number of pixels on the photo-image using image-processing software. In the tensile test, force-strain curves of the total skin and dermis with epidermis were obtained. Subsequently, a rule of mixtures was applied to determine the nonlinear mechanical properties of the hypodermis layer. In conclusion, we could define the uniaxial tensile behavior of the hypodermis, and additionally predict the weight effect of the dermis and hypodermis layers in the tensile test.

Uniaxial tensile tests were performed on porcine skin to investigate the tensile stress-strain constitutive characteristic at quasistatic deformations using uniaxial tensile tests. Experimental results were then used to determine the parameters of the various constitutive model types for rubber, including the Mooney-Rivlin, Yeoh, Ogden, and others. The Prony series viscoelastic model was also calibrated based on the stress relaxation test. To investigate the calibrated constitutive equations (visco-hyperelastic), the falling impact test was conducted. From the viewpoint of the maximum impact load, the error was approximately 15.87%. Overall, the Ogden model predicted the experimental measurements most reasonably. The calibrated constitutive model is expected to be of practical use in describing the mechanical properties of porcine skin.

The research was attempted to mimic the locomotion of the salamander, which is found to be one of the main animals from an evolutionary point of view. The design of the limb and body was started with the parametric studies of pneumatic network (Pneu-Net). Pneu-Net is a pneumatically operated soft actuator that bends when compressed fluid is passed inside the chamber. Finite Element Analysis software, ANSYS, was used to evaluate the height of the chamber, number of chambers and the gap between chambers for both limb and body of the soft mechanism. The parameters were decided based on the force generated by the soft actuators. The assembly of the salamander robot was then exported to MATLAB for simulating the locomotion of the robot in a physical environment. Sine-based controller was used to simulate the robot model and the fastest locomotion of the salamander robot was identified at 1 Hz frequency, 0.3 second of signal delay for limb actuator and negative π phase difference for every contralateral side of the limbs. Shin-Etsu KE-1603, a hyper elastic material, was used to build the salamander robot and a series of experiments were conducted to record the bending angle, the respective generated force in soft actuators and the gait speed of the robot. The developed salamander robot was able to walk at 0.06774 m/s, following an almost identical pattern to the simulation.

An analysis of sandwich beams with truss core is an important issue in many fields of industry such as civil engineering, automotive, aerospace or maritime. The objective of the present study is a nonlinear static response of sandwich beams subjected to the three-point bending test configuration. The beams are composed of two parent components: upper and lower laminated face sheets (unidirectional tape) and a pyramidal truss core manufactured by means of 3D printing. A polyamide filament strengthened with chopped carbon fibres – CF-PA-12 is used for the core development. The both, experimental and numerical analyses are presented. A detailed numerical model of the sandwich beam was developed in Abaqus software. The numerical model considers modelling of the adhesive joint with an additional layer of material placed between the parent components of the beam. A continuum hybrid solid shell elements were used to model the adhesive layer. In addition, a special care was taken to use an appropriate material model for the CF-PA-12 filament. To do so, the uniaxial tensile tests were performed on 3D printed samples. Having acquired the test data, a hyperelastic material model was evaluated based on a curve fitting approach.