Higher-order impact modeling of sandwich structures with flexible core

Abstract

In this study, a higher-order impact model is presented to simulate the response of a soft-core sandwich beam subjected to a foreign object impact. A free vibration problem of sandwich beams is first solved, and the results are validated by comparing with numerical finite element modeling results of ABAQUS and the solution by Frostig and Baruch [Frostig, Y., Baruch, M., 1994. Free vibration of sandwich beams with a transversely flexible core: a high order approach. Journal of Sound and Vibration 176(2), 195-208]. Then a foreign object impact process is incorporated in the higher-order model, and the contact force and deflection history as well as the propagation of transverse normal, shear, and axial stresses during the impact are analyzed and discussed. The validity of the model in the impact response predictions is demonstrated by comparing with finite element solutions of LS-DYNA. The calculated stresses caused by a foreign object impact are then used to assess failure locations, failure time, and failure modes in sandwich beams, which are shown to compare well with the available experimental results. The effects of impact mass, initial velocity, core stiffness, and core height on the impact stresses generated in the beams are discussed. The influences of impact mass and initial velocity on the contact force history are close to those by the linearized impact solution, but the proposed higherorder impact model captures the non-linear impact process and different generated stresses. Compared to the fully backed sandwich case, the core height shows a great influence over the impact process of a simply supported sandwich system, in which the global behavior of the sandwich is dominant; while the core stiffness shows minor effect over the impact process. The higher-order impact model of sandwich beams developed in the study provides accurate predictions of the generated stresses and impact process and can be used effectively in design analysis of anti-impact structures made of sandwich materials.

A theoretical investigation on low-velocity impact response of a curved sandwich beam

“…To model the marginal case of a flat sandwich, the curvature angle was considered small enough (θ 0 =1deg). The geometrical and mechanical properties of the beam are according to the paper of Yang and Qiao [7]. Fig.3 presents the results reported by Yang and Qiao [7] and the high order and layerwise theories developed in this study.…”

“…The geometrical and mechanical properties of the beam are according to the paper of Yang and Qiao [7]. Fig.3 presents the results reported by Yang and Qiao [7] and the high order and layerwise theories developed in this study. Fig.3 shows that the history diagrams of projectile velocity and vertical deformation are in a good agreement between different models.…”

“…In order to validate the presented theories, results of high order and layerwise models have been compared with those reported by Yang and Qiao [7] for a flat sandwich beam. To model the marginal case of a flat sandwich, the curvature angle was considered small enough (θ 0 =1deg).…”

“…The value of k c and p for sandwich structures can be determined by experimental tests. A common form of the indentation law is the Hertzian contact law which has been employed by several researchers to evaluate the impact response of sandwich structure, [2,[7][8][9][10]. In the Hertzian contact law, the value of p is 1.5 and k c is calculated according to the radius and Young's modulus of the projectile and top facesheet:…”

“…The numerical results show that this model could also be employed in dynamic problems. Yang and Qiao [7] studied the impact behavior of a sandwich beam using the HSAPT.…”