Effect of through thickness separation of fiber orientation on low velocity impact response of thin composite laminates

Abstract

The effect of separation of fiber orientation through the thickness of thin composites on their low velocity impact response is studied. The composites are prepared using unidirectional glass fiber reinforced epoxy through hand layup followed by vacuum bagging. The two dissimilar layups of composites considered have separation of composite layers with fibers having the same and different orientations through the thickness. The composites are subjected to low velocity impact using a drop-weight testing machine. The composites are evaluated using different performance parameters such as damage degree, first damage and maximum forces, first cracking energy, bending stiffness, elastic strain energy, elastic, residual and maximum displacements, permanent deformation, square-root delaminated area, delamination length and width, and contact duration. Among the two composites, it is observed that [90/-45/45/0] composite in which two layers with fibers having 90° and 0° orientations separating by two layers with fibers having -45° and 45° orientations, levels of deformation are lower and recorded force and square-root delaminated area are higher and lower, respectively for the same level of impact energy. Whereas, in case of [0/90/90/0] composite in which two layers with fibers having 0° orientations separating by two layers with fibers having 90° orientations, recorded force is lower and deformation and square-root delaminated area are higher. The [0/90/90/0] composite is having a comparatively more lateral spread of delamination and inter-layer opening than that of [90/-45/45/0] composite considering extensional and bending stiffnesses along longitudinal (A11, D11) and transverse (A22, D22) directions. This facilitates that lateral spread of damage within composite can be decreased by separating two layers of composite with 90° and 0° fiber orientations by two layers with -45° and 45° fiber orientations, i.e., [90/-45/45/0] composite.

Modeling the Repair of a Crack in an HDPE Pipe

“…For both fiber orientations α = 0° and α = 90°, the value of J-Integral is almost the same regardless of the value of the normalized length a/w (Fig. 6), what has been shown by Sharma et al [23] that lateral propagation of damage in the composite can be decreased by separating two layers of composite with 90° and 0° fiber orientations by two layers with 45° fiber orientations.…”

Maximizing the Performance of 3D Printed Fiber-Reinforced Composites

“…Understanding failure behavior is a complicated process involving a wide variety of factors, such as matrix micro-and macro-cracks, surface buckling, delamination, core failure, fiber breakage and fiber splitting, based on the composite design and constituting materials [33][34][35][36]. Load-deflection curves (Figure 5c) and the fractographies (Figure 6) are useful to explain the failure mechanism of the composites.…”

Repeated drop-weight impact tests on self-compacting concrete reinforced with micro-steel fiber

“…The accident impact of moving vehicles on columns and walls of structures is one example of which [1]. Other examples may be the impact of dropping objects from higher altitudes, impact of projectiles in wars or terrorist attacks [2,3], impact of water on hydraulic structures and offshore structures or even bridge piers [4,5]. Impact forces subject short term dynamic loads that subject the material to unusual and undesirable stresses especially for brittle materials like concrete.…”