When a bolt or pin is in direct shear, average V/A shear stress is used. Maximum VQ/It shear stresses are used for beams subject to shear and bending. But often in a Wide Flange beam average shear stress is used by using the area of the web and not the flanges, and you get close to the same result as the max shear stress formula. Even the max shear stress hand calculation is an approximation, because there are variations in shear stress not only top to bottom, but often left to right as well,as FEA might show. The safety factor has it covered. Nothing tops the good old fashioned hand calcs.chad mcelroy said:
besides checking for shear stresses in bolts or rods (using average V/A shear stress calculations when bolt or rod is subject to shear and not bending), you must also check for bearing stresses in the bolt and plate at the contact area between the bolt/rod and the connected plate hole wall. Most codes allow for some deformation and yielding at the bearing contact areas. I haven't done much research in ductile fracture theories. Shear tear out in the plate must also be checked for holes near edges.chad mcelroy said:
Average shear stress is used because it provides a more representative value of the stress experienced by a material. Maximum shear stress only represents the highest stress at a single point, while average shear stress takes into account the stress distribution over the entire surface of the material.
Average shear stress is calculated by dividing the total shear force acting on a material by the cross-sectional area of the material. This provides an average value of the shear stress experienced by the material.
Not necessarily. In some cases, the distribution of shear stress may be uniform, resulting in the average shear stress being equal to the maximum shear stress. However, in most cases, average shear stress will be lower than maximum shear stress.
Average shear stress is important in material testing because it provides a more accurate representation of the stress experienced by a material. This information is crucial in determining the strength and durability of the material, and helps in making design decisions.
One potential disadvantage is that average shear stress may not accurately represent the stress experienced at a specific point on the material. This is why it is important to also consider maximum shear stress in certain applications. Additionally, calculating average shear stress requires more complex mathematical calculations compared to maximum shear stress.
