Page 120 - Mechanics Analysis Composite Materials

Chapter 3. Mechanics of a unidirectional ply 105

Fig. 3.54. Simulation of pure shear in a square frame.

Fig. 3.55. A tubular specimen for shear test.

Fig. 3.56. Shear failure under compression.

and reaches the maximum value at a = 45". Shear failure under compression is
usually typical for unidirectional composites that demonstrate the highest strength
under longitudinal compression. On the other hand, materials showing the lowest
strength under compression exhibit transverse extension failure mode typical for
wood compressed along the fibers and shown in Fig. 3.57. This failure is caused by
tensile transverse strain whose absolute value is
E2 = V21-3 , (3.106)