Tensile/Impact strength relationship???
Tensile/Impact strength relationship???
(OP)
I have been asked to find a relationship between an impact strength and a tensile strength.
I have a welded part which must meet an impact test specification and I looking for a way to emulate that test with a simple tensile test.
Is there an equation or a conversion or any direct relationship between the two?
I have a welded part which must meet an impact test specification and I looking for a way to emulate that test with a simple tensile test.
Is there an equation or a conversion or any direct relationship between the two?





RE: Tensile/Impact strength relationship???
RE: Tensile/Impact strength relationship???
Maui
RE: Tensile/Impact strength relationship???
RE: Tensile/Impact strength relationship???
I am trying to emulate an impact test with a tensile test for its simplicity.
I build MacPherson struts and all the welded components that are attached to the strut are required to pass a specified load impact test. There are so very many different configurations of these welded brackets throughout the many different part numbers, that to build a test fixute with a dynamic loader (as I do for other simpler welded parts) would be a nightmare.
A brainstorming session turned up a suggestion that we build a tensile testing jig (easier to reconfigure) but I told them I didn't have any way to compare a tensile result to the impact specification. So the typical response was, "Your an engineer figure it out!!".
So I thought I might get a second opinion.
RE: Tensile/Impact strength relationship???
Your additional information raises other questions. What do you mean by "impact strength" and "impact test"? The previous responders assumed impact strength to mean a material's inherent impact strength as measured by a Charpy impact test. But, there are many "impact tests" for component level testing that may be closer to your needs. If you provide some additional details, we may be able to help you.
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Tensile/Impact strength relationship???
The suggestion was to enact a lbf test and make it equivelant.
CoryPad, I apologize, this is my first use of the forum and I am not exactly e-text savvy, so if I am violating the rules I apologize. I did review this FAQ you mentioned and believed I was following them? No?
RE: Tensile/Impact strength relationship???
A "ft-lb" test is not descriptive. Is the goal to ensure that welded components of your strut can absorb a certain energy level (X ft-lbf) without damage/failure? Do you have rate, temperature, or other factors to consider?
Regarding the FAQ, that is a standard part of my signature and appears on every post I make. You will see similar signatures from other users. It isn't meant to tell you that you posted something inappropriate - if you did, a user will "Red Flag" it and it will be handled by the site management.
Cory
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Tensile/Impact strength relationship???
RE: Tensile/Impact strength relationship???
That the only way to mimic this would be to force a dynamic factor by attempting to speed up a strain test. But then we are back to the point CoryPad made, we are wanting to know how much energy it will absorb and a rapid strain will be a poor way of showing that.
Thank you all for your assistance. My materials 101 isn't as rusty as I thought but I was having trouble with the techical descriptors.
All were a big help and the promptness is unreal!!!
RE: Tensile/Impact strength relationship???
RE: Tensile/Impact strength relationship???
Maui
RE: Tensile/Impact strength relationship???
FYI--for steels, the tensile strength can vary from 200-2000 MPa, while the Fracture toughness (the material variable most dictating impact strength, previously stated by Jim) varies likewise by an order of magnitude (source text: Materials Selection in Mechanical Design, Michael F. Ashby). There also tends to be an inverse correlation between these variables in steels--the higher the tensile strength, the lower the energy (due to brittle vs. ductile fracture). Somebody suggesting to you that it is easy to correlate these two variables does not appreciate that they are not directly interrelated.
Brad