© 2018, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 1823 Synthesis and Study on Effect of Thickness on 3-point Bending Strength of Sandwich Composites Lokesh KS Assistant Professor, Department of Mechanical Engineering, Srinivas Institute of Technology, Karnataka, India ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract :- Composite materials play a vital role in many industrial applications. Researchers are working on fabrication of new composites materials worldwide to enhance the applicability of these materials. Glass fiber reinforced polymer composites is widely used many industrial application particularly in the automotive industry due to advantages such as low weight, ease of processing, price and noise suppression. Sandwiched structure forms a new option for automotive industry. A sandwiched structure is a special type of sandwiched–structure composite that is fabricated by attaching two thin but stiff skins to a light weight but thick core. The core material is normally low strength material, but its higher thickness provide the sandwiched structure composite with high bending stiffness with low overall density. Keeping this in mind our present study concern about the preparation of sandwich composites by using glass fibre as skin and polyurethane foam as a core material and sample was prepared by hand layup method for two different thickness of the core which influence greatly on the mechanical properties of material. Testing of samples according to ASTM standard was done and phenomenal observations are accurately noted and results are tabulated. The qualitative comparison has been made to samples of different thickness to recommend the applicability of sample. It was observed that remarkable changes have been recorded as thickness of the sandwich affects greatly on resistance to bending, which is because of core material sustain greater value of load with its increased load bearing area. The experimental reading has been tabulated for all the loading conditions and performance oriented comparison is highlighted to show case the reasonable factor for the drastic changes under flexural loading conditions. Key Words: sandwich composites, core thickness, flexural rigidity. 1. INTRODUCTION Fiber-reinforced composites have found numerous applications in aerospace industry for their high specific stiffness. However, the cost of traditional composite materials is also considerable. Random chopped fiber- reinforced composites (RFCs) have emerged as promising alternative materials for lightweight structures due to their low cost and mass production capabilities [1]. Their potential application in, for example, automotive industry has been documented. In order to expand their use, accurate material characterization is required. The main difficulty in fully exploring model their geometry at the micro-level for high fiber volume ratios (35-40%). This difficulty becomes even more obvious at high aspect ratio fibers [2]. Glass-fiber reinforced composites (or glass- fiber reinforced plastics, GFRP) have seen limited use in the building and construction industry for decades. Because of the need to repair and retrofit rapidly deteriorating infrastructure in recent years, the potential for using fiber – reinforced composites for a wider range of applications is now being realized[3]. Mechanical properties of fiber-reinforced composites are depending on the properties of the constituent materials (type, quantity, fiber distribution and orientation, void content). Beside those properties, the nature of the interfacial bonds and the mechanism of load transfer at the interphone also play an important role[4].The reports studies on short fiber reinforced composites by different investigators are found to have focused mostly on the strength properties of the composites. They have described the influence of fiber shape in short glass fiber composites [5]. They have studied the flexural properties of misaligned short fibers reinforced polymers by taking into account the effects fiber length and fiber orientation. Recently, efforts to reduce the weight of automobiles by the increased use of plastics and their composites, have led to a growing penetration of short-fiber reinforced injection molding thermoplastics into fatigue-sensitive applications [6]. In general, short-fiber/polymer matrix composites are much less resistant to fatigue damage than the corresponding continuous fiber reinforced polyester (GRP) is widely used in pressure vessel and pipe line system for chemical industry [7].Keeping this historical evidence in mind the present study highlights the preparation of chopped strand mat glass fabrics sandwiched with polyurethane foam by varying the thickness and the mechanical tests have been done upon preparing the samples according to testing conditions. Comparative results resemble the influence of core thickness on mechanical properties of light weight materials. 2. MATERIALS & METHODOLOGY 2.1 THE RAW MATRERIALS USED  S glass fiber( chopped strand mat)  Epoxy Resin  Hardener  Polyurethane Foam (PU Foam) 2.1.1 Glass fibre Glass fiber has roughly comparable mechanical properties to other fibers such as polymers and carbon fiber. Although not as strong or as rigid as carbon fiber, it is much cheaper and significantly less brittle when used in composites. Glass fibers are therefore used as a reinforcing agent for many International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 05 Issue: 08 | Aug 2018 www.irjet.net p-ISSN: 2395-0072