The discussion revolves around the concepts of compressive strength, bulk modulus, and their relationship in the context of material failure. Participants are exploring the definitions and implications of these properties in relation to concrete under stress.
Some participants have provided insights into the nature of compressive strength and its distinction from other moduli, while others are seeking further clarification and assistance with the problem setup. The discussion is active, with multiple interpretations being explored regarding the failure behavior of materials.
There is an indication that the original poster may have received incomplete explanations from their tutor, leading to confusion about the concepts involved. Participants are also reflecting on their past experiences with related topics, suggesting a range of familiarity with the material.
The bulk modulus would allow you to calculate the amount volume strain, resulting from a given change in pressure ( ΔP ). The volume strain is dimensionless - think of it like a percentage change. If you draw a stress strain curve, think of the modulus as the slope of the curve in the linear region, and the Compressive strength as the point on the curve where it starts to fail.quicksilver123 said:
Good point. I should have stated that to let the OP know that those are not needed to solve the problem. The Compressive Strength is the maximum pressure that it is designed withstand before you are getting into risk of failure.Chestermiller said:
Actually, it is not the pressure (which is the isotropic part of the stress tensor) that causes failure. It is the anisotropic part (i.e., unequal principal stresses) that causes failure (along shear planes at an angle to the principal stresses). When we talk about compressive strength, we are talking about unixial loading of a bar or column, with zero principle stresses in the transverse directions. If we somehow placed the bar or column under isotropic pressure loading (like lowering it to the bottom of the ocean or placing it in a liquid high compressive chamber), it would not fail until a much higher compressive stress than the uniaxial compressive strength.scottdave said:
Once I learned dyadic notation, all my problems with tensors vanished.scottdave said:Thanks @Chestermiller . Yes it is starting to come back to me. It has been around 20 years, since I took that materials course. But I do remember when I first was introduced to tensors. I had a similar feeling to the first time that I was introduced to imaginary numbers.