13th International Conference on Fracture June 16–21, 2013, Beijing, China -1Mechanical properties properties of natural natural fiber polyester polyester composite composite sandwich sandwich panels JieLu1,*, BingYang2, Nandika D’Souza2, Sheldon Q Shi2 1 College of Aerospace and Civil Engineering, Harbin Engineering University, Harbin 150001, China 2 Department of Mechanical and Energy Engineering, University of North Texas, Denton 76207, USA * Corresponding author: lujie@hrbeu.edu.cn Abstract In the current work, a novel kenaf fiber reinforced composite sandwich panel was developed and fabricated. The kenaf fiber composites as sandwich face sheets were prepared at 55% (by weight) fiber content. PVC foams were joined using epoxy resin adhesive to fabricate sandwich structures. A series of mechanical tests, such as tensile, three-point bending and double cantilever beam, were carried out to know the mechanical behaviors of sandwich panels. Fracture and failure modes were also reported and discussed. The results show kenaf fiber reinforced composite sandwich panels have potential application in engineering construction of buildings. Keywords Natural fiber, Sandwich, Mechanical properties, Failure analysis 1. Introduction In recent years, the use of sandwich structures continues to increase rapidly due to their advantages, such as high strength/weight and stiffness/weight ratios, excellent heat resistance and favorable energy-absorbing capacity. They have been widely used in the satellites, aircraft, ships, automobiles, rail cars, wind energy systems, and bridge and civil constructions [1]. Most sandwich specimens analyzed in the past studies were made of polymer foam cores with composite face sheets or with metal face sheets [2–4]. Additionally, more assembly techniques, such as screw fasteners, adhesively joints, or blazed bonding, can be applied for bonding the core material and the face sheet. These applications and novel manufacturing techniques increase the requirement for the mechanical strengths of the sandwich structures in practical designs. Another question is that environmental protection becomes increasingly important. Thus, the use of natural fibers as reinforcements of polymer-based composites has been of great interest to many researchers [5–7]. Due to many advantages, such as low density, high specific strength and modulus, relative non-abrasiveness, ease of fiber surface treatment and wide availability. More important, they are renewable and biodegradable. In fact natural fibers are also much cheaper than synthetic fibers and could replace synthetics in many applications. If according to the design concept of sandwich structures, the natural fibers are used to fabricate the sandwich panel, it is predictable that such a “sandwich structure” with lightweight, high strength, bio-degradable and environmental friendly properties could be obtained. However, few studies have addressed this aspect. The objective of this work was to develop a novel sandwich structure based on natural fiber and PVC foam materials. Fabrication method including sheet molding compound (SMC) and bonding technique was introduced. A series of mechanical tests, such as tensile, bending and fracture properties, were carried out to understand the mechanical behaviors. 2. Materials preparation preparation Kenaf bast fiber was supplied by Kengro Corp (Charleston, MS, USA). It was short fiber form and
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