Papers by Author: Chen Guang Huang

Abstract: To study the relation between surface morphology and deformation mechanism of the target material under the shock, a flexible boundary loading, in laser shock peening (LSP), the macroscopic and microscopic surface morphology of a single crystal copper treated by LSP was investigated. The optical profilometer shows a 200-μm-deep pit forms on the shocked surface under LSP. The optical microscopy shows a set of parallel slip bands appear at the center of the shocked region and many vertical cross slip bands appear at the edge of shocked region. This indicates a large plastic deformation occurs by means of slip for the single crystal copper under LSP and the distributing features of slip bands correspond to the spatial distribution of the shock pressure. The results confirm that the surface morphology of materials under LSP can reflect the deformation mechanism and it can be a new method of studying the deformation mechanism of materials under LSP.

Abstract: In this paper, the real-time deformations and failures of LY12 samples loaded by an SHTB are investigated by an optical system, which consists of a high-speed camera, a flash lamp, a frame grabber and a synchronization device with the controlling accuracy of 1 microsecond. The deformation history of LY12 is obtained with a time interval of 10μs and the result is compared with that acquired by classic Hopkinson method at the same time. Besides, two different failure modes and the crack propagation velocity of LY12 specimen are detected in impact tensile process. The fracture textures after working are also surveyed by SEM and it shows that the dynamic fracture mode is affected by the microstructure of materials.

Abstract: In this paper, the mechanical properties of several aluminum alloys are obtained experimentally at different temperatures, from room temperature to about 4000C by using the Gleeble 1500 thermomechanical system. Besides, the thermal softening characteristics, effects of heating rate and temperature holding time are discussed in details. It is found that the strength of LF6, a kind of antirust aluminum alloy, is not sensitive to the heating rate (0.1-1000K/s) and temperature holding time (0-1h). However, the mechanical behaviors of other alloys depend on these factors very obviously. At last, these phenomena are discussed in the viewpoint of the microstructures and techniques of ageing strengthening of these alloys.

Abstract: In this paper, the dynamic behaviors of several kinds of high strength fibers, including Kevlar, UHMPE, glass fibers, carbon fibers etc., are investigated experimentally, with a Split Hopkinson Tension Bar（SHTB）. The effect of strain rate on the modulus, strength, failure strain and failure characteristics of fibers, under impact loading, is analyzed with the relative stress vs. strain curves. At the same time, the mechanism about the rate dependence of mechanical behaviors of various fibers is discussed based on the understanding on the microstructures and deformation models of materials. Some comments are also presented on the decentralization of experimental results, and a new method called traveling wave method is presented to increase the experimental accuracy. Research results obtained in this paper will benefit to understand the energy absorption and to build up the constitutive law of protective materials reinforced by high strength fibers.