Which material failure type is associated with shear stresses and can show a smooth break in ductile materials or a 45-degree break in brittle materials?

• A. Shear
• B. Tension
• C. Compression
• D. Bending

Answer: (A)

Shear failure occurs when the dominant load causes sliding along a plane within the material. When shear governs the break, the fracture surface shows distinct patterns: in ductile materials, substantial plastic deformation before fracture creates a smooth, flowing break along the shear plane; in brittle materials, crack propagation tends to follow a diagonal path, often about 45 degrees to the applied stress, giving a 45-degree break. This combination of a shear-plane fracture with these surface characteristics is what identifies this failure mode. Tension, compression, and bending describe other loading conditions and typically produce different fracture behaviors not driven primarily by shear along a plane.