What is the difference between xyshear stress and Max. shear stress?
I must calculate shear stresses at different time instants in QUAKE/W. There are two options to calculate shear stresses. 1. Under total stresses, there is an option called xyshear stress and 2. under shear stresses, max. shear stresses. The results of both for a particular node are different.
What are the calculation basics for these two?
There is no water in my model
Answers

To understand why the shear stress Txy at a particular node is different from the maximum shear stress (tmax), it is important to delve into the nature and calculation these stresses.
Shear Stress (txy): Is a component of the stress tensor in the xy plane. It represents the force per unit area acting parallel to the xy plane. It specifically refers to the stress in the plane defined by the x and y directions. It is a pointspecific and directional value, depending on the orientation of the plane in which it is measured.
Maximum Shear Stress (Tmax): Is the highest value of shear stress that can occur on any plane within the material. It is not restricted to a specific plane like xy. Tmax is obtained by considering all possible planes within the material. It is calculated from the components of the stress tensor, considering bot normal stresses (sigma x and sigma y) and the shear stress (Txy).
Here sigma x and sigma y are the normal stresses in the x and y directions, respectively, and Txy is the shear stress in the xy plane.
The calculation of the Tmax includes the combined effects of normal stresses (sigma x and sigma y) and shear stress (Txy), Which is not the case when simply evaluation Txy.
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