When setting up a structural simulation study, it never seems like you have ALL the information you need. Without exception, you’ll have to be content with making approximations and assumptions. Absent or unreliable material data is one key area that virtually all simulation users will need to question.
How precise do you need to know the properties of your material to obtain an acceptable accuracy level of your result of interest? If you are looking for approximate deflections on a steel part, you may be able to get away with entering simple generic properties such as the ones shown below:
If you browse through many of the steels in our database, almost all of them have an Elastic Modulus between 190-210 GPa. This means deflections in a linear static study would vary by about 10% depending on what steel you select. If this is acceptable, maybe try a steel that is on the conservative end of this spectrum (i.e., 190GPa). Don’t be misled, however, because even the elastic modulus can vary by more than 10% for some special classes of steel.
For more complex properties that you might need for a Nonlinear analysis, one of the easiest simplifications you can make for some materials is to use a “perfectly plastic” curve. This method only requires that an Elastic Modulus and Yield Strength are known. See the comparison shown below to see how similar the perfectly plastic assumption compares to the SS curve provided for “Alloy Steel (SS)” for strains under 2%.
There are more sophisticated methods for approximating stress-strain data if you also know the Ultimate Tensile Strength of the material.
You can use tools like this fatigue calculator for approximating S-N curve data. This website also has a few other tools. And, there are a few websites similar to this one that have tools to help you approximate material data.
These recommendations can be helpful for certain classes of problems. But, they can also be potentially dangerous if you’re not conservative and careful with understanding the effects of these assumptions. This is why you should get out your textbook, browse through Wikipedia pages, view some YouTube videos, talk to your peers, etc. to make sure you understand some of the properties. This will allow you to make sound decisions about which simplifications to allow and which ones you’ll have to invest more time and energy to avoid.
At a bare minimum, a few of the properties you’ll likely deal with and need to understand on a regular basis are:
These properties are highlighted in red for Static studies for a reason.
About Shaun Bentley
Shaun Bentley is passionate about Applied Mathematics and Engineering which led him to pursue and understand real world applications of FEA, CFD, Kinematics, Dynamics, 3D and 2D modeling. He teaches simulation classes to both new and advanced users attending training at GoEngineer. Since 2006, Shaun has been working with simulation tools to solve real world engineering problems. With every new project, he seeks to find ways to push Simulation to its uppermost limits.
Get the latest articles delivered daily to your inbox, unsubscribe at any time.