June 12, 2021 at 1:04 pm
peteroznewman
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DESIGN FOR STRENGTH MODEL
A simple model would consist of the three solids: concrete, epoxy and steel, having Shared Topology applied so that no bonded contact is required. This is easily done in SpaceClaim if the three solids are in one component, just go to the Workbench tab and click the Share button. Before doing that, on the Design tab, click Split Solid and split the steel at the end of the epoxy, and then repeat to split the concrete at the end of the epoxy. That will allow the bodies to continue to have clean hex meshing applied.
In Mechanical, use Mesh Controls such as Sweep to ensure there are at least four elements through the thickness of the epoxy. I suggest using the fixed support only on the bottom face of the concrete so that there is no boundary condition on an edge that the epoxy can touch.
Solve the model and plot the applied Force vs the Von Mises Equivalent Stress. Look up the Force that just exceeds the value of Tensile Yield Strength in the Equivalent Stress column. That is one measure of the failure load. For many design tasks, that is all that is needed since the design goal is to size the area of adhesive so that the Equivalent Stress stays below the Tensile Yield Strength by some factor of safety at the maximum load expected during the product lifetime. This is the most common type of analysis, though I have used the Tensile Ultimate Strength as the threshold and the Max Principal Stress as the metric to evaluate the failure load.
You can plot the force vs deformation from this model and you will find it is an almost straight line. That is because the definition of Yield Strength is when the material stress deviates just 2% from a straight line.
SIMULATE TOTAL SHEAR FAILURE MODEL
Unfortunately, what you want is to simulate the Force vs Deformation plot that the testing machine plots during the total destruction of the joint. That is because the joint continues to be present for loads much higher than the point when the yield strength of the epoxy is reached. This is a much more difficult model to build and to tune up to match experimental data. It requires a lot more material data about the Epoxy than you have. There is a whole chapter in the ANSYS help guide on this. Section 4.11 of Mechanical APDL Theory Manual (R2019 thru R2021) covers how the Cohesive Zone Model (CZM) works in both interface elements and contact elements.
DESIGN FOR STRENGTH MODEL
A simple model would consist of the three solids: concrete, epoxy and steel, having Shared Topology applied so that no bonded contact is required. This is easily done in SpaceClaim if the three solids are in one component, just go to the Workbench tab and click the Share button. Before doing that, on the Design tab, click Split Solid and split the steel at the end of the epoxy, and then repeat to split the concrete at the end of the epoxy. That will allow the bodies to continue to have clean hex meshing applied.
In Mechanical, use Mesh Controls such as Sweep to ensure there are at least four elements through the thickness of the epoxy. I suggest using the fixed support only on the bottom face of the concrete so that there is no boundary condition on an edge that the epoxy can touch.
Solve the model and plot the applied Force vs the Von Mises Equivalent Stress. Look up the Force that just exceeds the value of Tensile Yield Strength in the Equivalent Stress column. That is one measure of the failure load. For many design tasks, that is all that is needed since the design goal is to size the area of adhesive so that the Equivalent Stress stays below the Tensile Yield Strength by some factor of safety at the maximum load expected during the product lifetime. This is the most common type of analysis, though I have used the Tensile Ultimate Strength as the threshold and the Max Principal Stress as the metric to evaluate the failure load.
You can plot the force vs deformation from this model and you will find it is an almost straight line. That is because the definition of Yield Strength is when the material stress deviates just 2% from a straight line.
SIMULATE TOTAL SHEAR FAILURE MODEL
Unfortunately, what you want is to simulate the Force vs Deformation plot that the testing machine plots during the total destruction of the joint. That is because the joint continues to be present for loads much higher than the point when the yield strength of the epoxy is reached. This is a much more difficult model to build and to tune up to match experimental data. It requires a lot more material data about the Epoxy than you have. There is a whole chapter in the ANSYS help guide on this. Section 4.11 of Mechanical APDL Theory Manual (R2019 thru R2021) covers how the Cohesive Zone Model (CZM) works in both interface elements and contact elements.
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