Effect of cutout geometry on the failure strength of symmetric laminates under uniform heat flux

The present work aims to investigate the thermal stress distribution in an infinite symmetrical laminated composite plate with a polygonal cutout to determine the laminate failure strength based on the first ply failure according to Hashin–Rotem and Tsai–Wu criteria. Lekhnitskii’s solution technique has been used to obtain the required potential functions. The extension of the technique used for the circular and elliptical cutouts into polygonal cutouts was performed using conformal mapping function in accordance with the procedure of complex variables. The main parameters such as cutout orientation, bluntness factor, the aspect ratio of the cutout, as well as stacking sequences in composite plates with symmetrical laminates made of glass/epoxy material containing triangular, square, pentagonal, and hexagonal cutouts have been examined. According to the research findings, it is possible to improve the failure strength of perforated plates by appropriate selection of cutout shapes along with the optimum values of the effective parameters. The unexpected result was that circular geometry was not always the best choice for the cutout because the selection of appropriate values for the parameters under consideration for a laminate with non-circular cutout leads to higher failure strength compared to the same plate with circular cutout.

Granulated Rest Frames Outperform Field of View Restrictors on Visual Search Performance

Dynamic field of view (FOV) restrictors have been successfully used to reduce visually induced motion sickness (VIMS) during continuous viewpoint motion control (virtual travel) in virtual reality (VR). This benefit, however, comes at the cost of losing peripheral awareness during provocative motion. Likewise, the use of visual references that are stable in relation to the physical environment, called rest frames (RFs), has also been shown to reduce discomfort during virtual travel tasks in VR. We propose a new RF-based design called Granulated Rest Frames (GRFs) with a soft-edged circular cutout in the center that leverages the rest frames’ benefits without completely blocking the user’s peripheral view. The GRF design is application-agnostic and does not rely on context-specific RFs, such as commonly used cockpits. We report on a within-subjects experiment with 20 participants. The results suggest that, by strategically applying GRFs during a visual search session in VR, we can achieve better item searching efficiency as compared to restricted FOV. The effect of GRFs on reducing VIMS remains to be determined by future work.

Buckling Strengths of Composite Plate Using Shape Memory Alloy under In-Plane Shear

In this article, we analyze the strength and buckling response in the plane shear load fixed at the corner of the composite plate. The fem is formulated is done on the basis of first-order shear deformation theory and assumptions of von Karman. The Newton-Raphson technique is considered to analyze the non-linearity algebraic equation. The effect of shape memory alloy in shear load and buckling response is discussed. In this study we analyze the two cases in the first simple carbon/epoxy plate is analyze and then we use the shape memory wire embedded in the plate which is about 1% of the volume of the plate and studies the buckling response effect on the plate. In the second case we use Shape Memory Alloy plate and loading but a circular cutout at the middle of the plate this case we analyze for both with the use of shape memory alloy and without the use of shape memory. It is observed that the shape memory alloy increases the strength of the plate in both cases. The whole simulations are done using Ansys workbench software v 2020R2.

An Extended Bond-Based Peridynamic Approach for Analysis on Fracture in Brittle Materials

To enhance the calculation accuracy of bond-based peridynamics (BPD), a novel attenuation function is introduced to describe the effect of internal length on nonlocal long-range forces. Furthermore, the expression of the micromodulus function is deduced, and the corresponding fracture criteria are established. The validity and accuracy of the extended bond-based peridynamic approach are illustrated by three numerical examples: 2D isotropic plate under uniaxial loading; plate with a circular cutout under quasi-static loading; and a diagonally loaded square plate with a center pre-existing crack. Finally, the influence of the width and the angle of the pre-existing crack on the fracture initiation time and the crack propagation paths are studied by applying the proposed approach.

Experimental and numerical investigation of stiffener effects on buckling strength of composite laminates with circular cutout

In the notched structures, to achieve maximum buckling resistance in comparison with structural weight, the optimal design of a stiffener is very important. In this research, after a review of the existing literature, nonlinear buckling behavior of composite plates containing the cutout with three different designs of stringer was investigated. The considered stiffeners are planer, longitudinal, and ring types. The buckling experiments were carried out on the stiffened plates containing a circular notch. Moreover, to achieve an efficient prediction of the buckling in the stiffened laminate with the hole, a finite strip method is developed based on the Airy stress function and von Karman’s large deformation equations. Studies show that there is a good agreement between the postbuckling behaviors derived from developed finite strip method with experimental results. Fast convergence of the considered finite strip method compared with the finite element results shows its efficiency for prediction of buckling behavior in laminated composites. The results show that the buckling load-bearing capacities of perforated plates with a longitudinal and planer stiffener are higher compared with the other stiffener, respectively. The detailed parametric study on the effects of thickness of the plate and stiffener and opening diameter on buckling behavior was performed using experiments and modeling.