How are you using the sign? What I mean is, how is it relevant to you? All that the sign does is tell you if the hydrostatic stress is positive or negative. Using the other invariants would not be correct.
If you're creating some program or Excel spreadsheet, I'd just default to positive if...
I think their parenthetical comment is an error. I'm pretty sure equivalent stress is von Mises stress here, which is the second invariant of the deviatoric stress tensor.
Be careful using the word validate, because it has a very specific meaning in the analysis world. Validation is part of the Verification and Validation (V&V) process. Validation can only be done with physical test data (or maybe other analyses that have been validated).
Here's a good overview...
It's not an unreasonable comparison if the point is to show that EVs do not produce significantly lower particulate emissions than ICEs. If they just compared the total emissions for both vehicles and said they're the same then people would either 1. Not believe it, or 2. Ask how that could be...
The first invariant of the stress tensor is the trace, which is sigma_xx + sigma_yy + sigma_zz, which is also three times the hydrostatic stress (i.e. -3 * Pressure). You should double check that this is really what you are getting from the software, because it seems like an odd quantity to...
Jhardy1 got it. In addition to the constraint issue that you have, you also aren't supplying the full load that the tank will see. You're missing the load generated by the pressure on the excluded area. If you aren't concerned about the expansion behavior of the neck area, an easy fix would...
Does the cylinder expand under the pressure load? If you're getting zero reaction force at point C, that point must be moving in the -X direction and the cylinder is rotating about A-B (for a Y=0 constraint there) to allow for the expansion. I would be interested in seeing X and Y displacement...
I don't think you need to change your design significantly to fix the problem. Here's an example build that doesn't have super tight tolerances and it still works fine. They are just using a bearing and a copper tube for the feeding mechanism. Maybe the v-grooves are the problem. Try...
These questions should be posted to the Student's Area: https://www.eng-tips.com/threadcategory.cfm?lev2=105
1. Do you understand the material model that you are using? Where did the parameters come from? Have the parameters been validated already on other similar problems? Concrete damage...
Stress and strain are tensors. You are plotting scalars. Which components of stress and strain are you actually plotting? Unless you're simulating a uniaxial tensile test, you shouldn't expect your results to look like a uniaxial stress-strain curve.
A few notes:
1. The conversion formulas you are using are only valid for uniform elongation (i.e. before necking), and assume a Poisson ratio of 0.5 for the plastic deformation (often a reasonable assumption).
2. Do you actually care about the material behavior at 600% strain? Limiting your...
Look at your input strains and calculate the stress by hand. If the hand calculation is also zero, there's a problem with your constitutive model. If you get a different result, it's a problem with your implementation of the model.
A static analysis is one where your boundary conditions are not changing, and your solution is not changing. It's also generally assumed that the BCs were applied slowly.
A transient analysis just means things are changing over time, and you probably care about the solution at multiple time...
Side Note:
FEA codes generally don't know/care what your units are. Whether your model is 5 millimeters, or 5 meters makes no difference. What is important is relative movement.
1. Is your material going to behave differently at 5" of deflection compared to 1" of deflection? (i.e., are you...
I agree with the other replies. But just because it's bothering me, I wanted to point out that method 1 is overly complicated. It's effectively just taking the sign of the trace of the stress tensor, which is the same as the sign of the hydrostatic stress. There's no need to have the...
Are you able to share an example component and the material that it's made out of? I wouldn't expect size changes due to hydrostatic compression to have any significant effect, unless it's a very compliant material. However, it is possible for hydrostatic stress to affect the failure limit...
I don't know anything about the method you're talking about. But what do you mean when you say the elements are in compression? Is it based on your minimum principal stress plot? The minimum principal stress is usually going to be negative for most stress states. What does a plot of the...
Duh, I completely forgot about that part. My guess now is they are threaded separately, and it's just not that critical to have both threads perfectly in sync. There is going to be some amount of play in the threads. And if the nut doesn't align perfectly with the start of the thread the...
