DMBocci
Mechanical
- Apr 5, 2018
- 3
Hello All,
I have been involved with testing Al.7068-t6511 for some of our applications. We have performed room temp and elevated temp tensile and fatigue testing with good results.
We have also have tested in a few applications with short cycles.
My manager is weary about producing more components for customer use with the material until we are sure that we have our heads wrapped fully around the material properties and response.
I have been treating this material like any other; Use temperature dependent tensile properties and we have chosen to limit the maximum stress state to 85-90% of yield as a safety factor.
Some of our applications will produce temperatures at about the 300deg.F mark, plus or minus a bit.
Our 300deg testing of this material yielded good results. But I also know that we are close to the limit of most aluminum alloys strength drop-offs regardless of 7068's high strength.
Our fatigue predictions are very basic at this point and is something we are developing.
I need to convince my manager that we are covering ourselves in our analysis of using this material.
Keep in mind that we use a lesser strength aluminum alloy in our applications that is widely used across our industry.
So, knowing the strength of that alloy and using it in our simulations as well as empirical data and experience, seems that I should be able to apply the same principles to the new material.
But I am not a materials engineer, so...
Is there anything that I am leaving out or not taking into consideration when using this material?
If it meets the stressed state criteria for our designs with yield strength, expansion, modal response, etc.. what am I not accounting for, if anything?
Creep, fatigue phenomenon, anything else that could show up that I am not aware of? Any deal breakers with ways to test or verify that we will be ok?
Thank you for looking.
Turbocharger and heat exchanger design engineer.
I have been involved with testing Al.7068-t6511 for some of our applications. We have performed room temp and elevated temp tensile and fatigue testing with good results.
We have also have tested in a few applications with short cycles.
My manager is weary about producing more components for customer use with the material until we are sure that we have our heads wrapped fully around the material properties and response.
I have been treating this material like any other; Use temperature dependent tensile properties and we have chosen to limit the maximum stress state to 85-90% of yield as a safety factor.
Some of our applications will produce temperatures at about the 300deg.F mark, plus or minus a bit.
Our 300deg testing of this material yielded good results. But I also know that we are close to the limit of most aluminum alloys strength drop-offs regardless of 7068's high strength.
Our fatigue predictions are very basic at this point and is something we are developing.
I need to convince my manager that we are covering ourselves in our analysis of using this material.
Keep in mind that we use a lesser strength aluminum alloy in our applications that is widely used across our industry.
So, knowing the strength of that alloy and using it in our simulations as well as empirical data and experience, seems that I should be able to apply the same principles to the new material.
But I am not a materials engineer, so...
Is there anything that I am leaving out or not taking into consideration when using this material?
If it meets the stressed state criteria for our designs with yield strength, expansion, modal response, etc.. what am I not accounting for, if anything?
Creep, fatigue phenomenon, anything else that could show up that I am not aware of? Any deal breakers with ways to test or verify that we will be ok?
Thank you for looking.
Turbocharger and heat exchanger design engineer.
