Flexible matrix composites are a class of fiber-reinforced polymers characterized by a low modulus of elasticity and high ultimate strain of thematrixmaterial. Such composites are attractive for power transmission shafts, which are commonlymade via processes that cause undulation (waviness) along the path of the reinforcement fibers, such as filament winding and braiding. Fiber undulations can be expected to reduce the in situ modulus and strength of the compositematerial in the fiber direction. The reported investigation proposes and evaluates a method for determining the effective in situ properties of the plies in filament wound tubes so that classical lamination theory (CLT) can be used to calculate effective ply-level stresses and to predict the overallmodulus and strength of tubes loaded in axial compression. An experimentalmethod is proposed to back-calculate the undulation-influenced ply properties fromrepresentative filament wound tubes using CLT together with other required ply properties determined via simpler conventional tests. This approach, along with an interactive failure criterion proposed to predict fiber microbuckling in the presence of combined compression and shearon the fibers, is able to accurately predict the axial compressivemodulus and strength of a variety of tubes made with different winding angles and matrix moduli. In general, the fiber-direction compressive strength of the composites increased with increasing matrix modulus and decreased in the presence of undulation. The reduction in strength due to undulation wasmore apparent with increasingmatrixmodulus. The fiber-direction modulus of elasticitywas not very sensitive to matrixmodulus in undulated composites. Undulation reduced the fiber-directionmodulus significantly relative to unidirectional composites, although the percent reduction could not be correlated withmatrixmodulus.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Mechanics of Materials
- Mechanical Engineering