Selection of fiber orientation around geometric discontinuities in designing against failure of GFRP laminates

Roselita Fragoudakis,S Pantelakis,S Koubias

doi:10.1051/matecconf/201818801010

Abstract

Determining fiber orientation around geometric discontinuities is challenging and simultaneously crucial when designing laminates against failure. This study presents an approach for selecting the fiber orientations in the vicinity of a geometric discontinuity. Maximum stresses in the discontinuity region are calculated using Classical Lamination Theory and the stress concentration factor. The use of the Tsai-Hill and Tsai-Wu failure theories estimate the minimum moment to cause failure in a lamina. Fiber orientations around the discontinuity are obtained using the Tsa-Hill failure theory.

Highlights

Fiber reinforced laminates have become optimum material alternatives to metals in major applications and industries
Research has shown that replacement of monoleaf steel springs with a laminated Glass Fiber Reinforced (GFRP) leaf, significantly reduces the weight of the leaf spring by more than 20%, without sacrificing strength and performance [1]
The approach focuses on using Classical Lamination Theory (CLT) in conjuction with the Tsai-Hill and Tsai-Wu failure theories to determine the minimum moment to cause failure in the laminate in the absence of a discontinuity, and the effect of the geometric stress concentration factor under bending, to determine the momen to cause failure in the presence of a circular hole

Summary

Introduction

Fiber reinforced laminates have become optimum material alternatives to metals in major applications and industries. Examples are fiber reinforced laminated leaf springs in vehicle suspension systems This type of composites of high strength to weight ratio and the flexibility to select and optimize the reinforcing phase (fibers) orientation allow for the desired stiffness, mechanical properties, and performance of the structure. Long unidirectional fibers offer high strength and stiffness to laminated FRP beams Geometric discontinuities, such as holes, fillets, and tapered edges interrupt the unidirectionality of the fibers and may affect the properties and performance of the laminate. The approach focuses on using CLT in conjuction with the Tsai-Hill and Tsai-Wu failure theories to determine the minimum moment to cause failure in the laminate in the absence of a discontinuity, and the effect of the geometric stress concentration factor under bending, to determine the momen to cause failure in the presence of a circular hole. The fiber oreintation in the viccinity of the hole is determined based on this latter minimum moment

Laminate Beam

The Vicinity around the Hole

The optimization process

Results

Conclusions