PROPERTIES IN SHEARShear stress plays an important role in the failure of ductile materials (which resist to normal stress by undergoing large plastic deformations, but fails by rupturing under shear stress. )However, the shear tests have not met wide acceptance and use that have been given to tension test. This unpopularitymay largely be due to the fact that an idea about the shear properties of a material can often be obtained from the tensile properties (eg. Ssy=~.!Sy). "onse#uently the shear test are usually conducted to obtain a measure of shear strength for speci$c applications.PROPERTIES IN SHEARTypes of Shear StressesThere are two main types of shear categori%ed due to the loadings. &ne is the direct or transverse shear stress and the other is the pure or torsional shear. (a)'irect Shear Stress (rivets ( beams are e)amples)(b)Torsional Shear Stress (Shafts are sub*ected to pure torsion)'i+erences between shear tests'irect or transverse shear tests are usually employed to obtain a shear strength (Ssy or Ssu) for speci$c applications ,hereas torsion test is usually employed to evaluate the shear behaviour and properties of a material (similar to the tensile test of materials)-roperties in direct shear'irect shear tets is employed in various ways as seen in $gure. The specimen is usually clamped in a $)ture and a shearing force . is applied through a shear tool and the ma). /oad . is determined.0 types of direct shear tests are12Single shear test (a)2'ouble shear test (b)and2-unch shear test (c)3n direct shear tests, usually the ma) load . (re#uired to shear the test specimen) is determinedThe same ma)imum load is then converted to the ma). direct shear stress (ultimate strength in shear ) via suitable e#uation.This test however does not provide reliable information for the properties (such as yield, sti+ness, resilience etc) of material in shear.This test provides only the ultimate strength of material in shear. 4ven this property is not always reliable due to factors such as1Hardness, sharpness and correct setting of shearing tools5ending stresses and friction between the parts etcTorsion TestTorsion tests are done on special type of machines which have been developed especially for this purpose. These tests are carried out applying a given twisting moment to one end of a specimen while measuring the deformation as angular displacement at the other end.The torsion test is not used in material speci$cation to the same e)tent as the tension test. The main reason for lac6 of popularity of torsion tests arises from the fact that no uniform shear stress can be generated within the material. 7evertheless, the torsion test is still usefull in determination of material properties such as Shear modulus of elasticity 8 (9), torsional yield strength Ssy(99) andshear modulus of rupture Su(999).8: (;odulus of