Chang-Gyun Jung

Bending behaviors of metallic sandwich plates with a sheared dimple core under simply supported loading

In this study, the bending responses of metallic sandwich plates with a sheared dimple core were investigated through the 3-point bending tests and dynamic plane bending tests. It was experimentally shown from the uniaxial tensile tests that the yield and tensile strengths of the brazed face sheet were weaker than those of the welded face sheet. A mild steel sheared dimple core was fabricated by the sectional forming process and then bonded with DP590 face sheets by multi-point resistance welding. Analysis for large deformation of a sandwich plate subject to 3-point bending was carried out, where frictional work was considered and a face sheet was treated as a rigid-plastic material based on Hollomon’s flow rule. Load—deflection curves and the deformed shapes of the finite element method computations and the experiments were efficiently predicted by the proposed analysis. The effect of frictional work on the peak load and energy absorption increases as the bending angle increases. The dynamic bending responses of the sandwich plates, such as the effect of a deformed shape, failure mode, energy absorption and absorption ratio were compared with those of a high-strength steel sheet. It was demonstrated that a bendable sandwich plate was stronger construction than a high-strength steel sheet under the tested conditions, despite the weight reduction and weaker properties.

Fabrication of Metallic Sandwich Plates with Inner Dimpled Shell Structure and Static Bending Test

Metallic sandwich plates with various inner cores have important new features with not only ultra-light material characteristics and load bearing function but also multifunctional characteristics. Because of production possibility on the large scale and a good geometric precision, sandwich plates with inner dimpled shell structure from a single material have advantages as compared with other solid sandwich plates. Inner dimpled shell structures can be fabricated with press or roll forming process, and then bonded with two face sheets by multi-point resistance welding or adhesive bonding. Elasto-plastic bending behavior of sandwich plates have been predicted analytically and measured. The measurements have shown that elastic perfectly plastic approximation can be conveniently employed with less than 10% error in elastic stiffness, collapse load, and energy absorption. The dominant collapse modes are face buckling and bonding failure after yielding. Sandwich plates with inner dimpled shell structure can absorb more energy than other types of sandwich plates during the bending behavior.

A STUDY ON THE BEHAVIOR OF A THIN STS 304 SHEET WITH A FREE BOUNDARY CONDITIONS SUBJECTED TO IMPACT LOADING

The objective of this paper is to investigate into impact behaviors of a STS 304 sheet with a thickness of 0.7 mm in a free boundary condition subjected to impact loading by a hemispherical impact head using drop impact tests and the three-dimensional FE analyses. The drop impact tests and the FE analyses were conducted with different impact energy ranging from 37.0 J to 45.7 J. From the results of the impact tests, the influence of the impact energy on the force-deflection curve, the absorption mechanism of the impact energy and deformation behaviors of specimen were examined quantitatively. Through the FE analyses, the variation of stress-strain distributions and characteristics of the local deformation during the impact of the specimen were investigated.