A reconstructed edge-based smoothed DSG element based on global coordinates for analysis of Reissner–Mindlin plates

A reconstructed edge-based smoothed triangular element, which is incorporated with the discrete shear gap (DSG) method, is formulated based on the global coordinate for analysis of Reissner-Mindlin plates. A symbolic integration combined with the smoothing technique is implemented to calculate the smoothed finite element matrices, which is integrated along the boundaries of each smoothing cell. Numerical results show that the proposed element is free from shear locking, and its results are in good agreement with the exact solutions, even for very thin plates with extremely distorted elements. The proposed element gives more accurate results than the original DSG element without smoothing, and it can be taken as an alternative element for analysis of Reissner-Mindlin plates. The prominent feature of the present element is that the integration scheme is unified in the smoothed form for all of the finite element matrices.

A MESH-FREE ALGORITHM FOR DYNAMIC IMPACT ANALYSIS OF HYPERELASTICITY

A mesh-free method based on local Petrov-Galerkin formulation is presented to solve dynamic impact problems of hyperelastic material.In the present method,a simple Heaviside test function is chosen for simplifying domain integrals.Trial function is constructed by using a radial basis function （RBF） coupled with a polynomial basis function,in which the shape function possesses the kronecker delta function property.So,additional treatment is not required for imposing essential boundary conditions.Governing equations of impact problems are established and solved node by node by using an explicit time integration algorithm in a local domain,which is very similar to that of the collocation method except that numerical integration can be implemented over local domain in the present method.Numerical results for several examples show that the present method performs well in dealing with the dynamic impact problem of hyperelastic material.

Structure Design and Energy Absorption Mechanism of a New Type of Armor Inspired from Armadillos

Dermal armor,such as fish scales or armadillo osteoderms,has been known to exhibit high performance and good flexibility defending against attack.The top layer of the dermal armor usually consists of a segmented hard bony layer.The soft inner layer composed of collagen fibers connects and holds the hard layer.Inspired by the dermal armor of armadillos,bioinspired protection armor is studied for impact resistance.The hexagonal scales tessellate the surface continuously and work as the hard bony layer protecting the soft inner layer from penetration.Ultra-high molecular weight polyethylene(UHMWPE)is used as the connectivity layer to support and hold the scales.To investigate the dynamic response of the bioinspired protection armor,drop weight impact tests are carried out.A finite element model is established to study the dynamic response of bioinspired protection armor.The impact process images captured by a high speed camera and the experimental data of drop hammer acceleration tests verify the validity of the numerical model.The dynamic resistance behavior and the synergy effect of each part of the bioinspired protection armor combined with the protected objects are studied in detail by numerical simulation.The results show that the bioinspired protection armor has marked energy absorption ability.A synergistic dissipation mechanism is activated in the impact process,which can dissipate impact energy and make the impact load distribution more uniform.The UHMWPE between the outer layer and the soft substrate plays a significant role not only related to support and connection,but also for the force balance and energy absorption.The mechanism of energy absorption of the bioinspired protection armor revealed in this paper can be taken as a new guideline for designing a novel protective armor.