Changxian Wang

Fire protection design for composite lattice sandwich structure

Abstract Composite lattice structures are of considerable mechanical property and multifunctional design flexibility. However, the relatively low operating temperature of polymer composite prevents its application in high temperature or fire-proofing structures. Here, we propose a type of lightweight composite lattice sandwich structure that is capable of fire proofing as well as load bearing. In our design, the composite lattice sandwich structure is filled with heat insulation materials to interdict the thermal radiation and convection between its two facesheets. The top facesheet of the structure is covered with intumescent coating to isolate fire. Moreover, thermoresistant resin or flame retardant is adopted in manufacturing the top facesheet to improve its thermoresistance. A design procedure has been developed for such kind of fire-proofing structure, by which the material and geometry of the structure can be determined according to the fire-proofing effect. It was demonstrated by experiment that a 30-mm-thick structure, designed by the present procedure, was able to isolate 945°C fire load on the exposed surface for 3600 s, keeping the unexposed surface temperature rise below 139°C.

A novel broadband waterborne acoustic absorber

In this paper, we extended the ray tracing theory in polar coordinate system, and originally proposed the Snell–Descartes law in polar coordinates. Based on these theories, a novel broadband waterborne acoustic absorber device was proposed. This device is designed with gradient-distributing materials along radius, which makes the incidence acoustic wave ray warps. The echo reduction effects of this device were investigated by finite element analysis, and the numerical results show that the reflectivity of acoustic wave for the new device is lower than that of homogenous and Alberich layers in almost all frequency 0-30 kHz at the same loss factor.