Amil 1 Posted May 13, 2019 Report Share Posted May 13, 2019 Speaking of cars, in particular of the chassis, if we keep a car stopped for years, will the weight of the engine and all the components form cracks in the crystalline microstructure of the iron? if we think about a spring, if we leave it compressed for so long it will lose its ability to flex, it will not come back as before (i guess), isn't it the same for a frame that has to hold up an engine for years? perhaps there is a load limit below which the piece will return as before also being compressed for many years? What happens to the metal microstructure in these cases? Correct me if I'm wrong. if the weight of the motor has been designed to keep the deformation of the underlying frame always in the "elastic" and not "plastic" area, how can it damage the metal in the absence of external environmental attacks? thanks Muyiwa Gideon Adimula 1 Quote Link to post Share on other sites
DrD 846 Posted May 26, 2019 Report Share Posted May 26, 2019 Cracks do not grow by themselves. Most cracking is due to fatigue, and that requires motion. A motionless car will not crack. DrD Abdurrahman Ismail and Ojas Mendapara 2 Quote Link to post Share on other sites
Ojas Mendapara 0 Posted May 27, 2019 Report Share Posted May 27, 2019 Crack will not happen because it is ideal condition for chassis with respect to stress strain diagram. the material corrosion is other topic for debate. No deformation and crack generated at ideal condition because as per stress strain diagram material do not react at the point of maximum stress point. Quote Link to post Share on other sites
Amil 1 Posted June 18, 2019 Author Report Share Posted June 18, 2019 Thanks for the answer, i have another questions please, about stress relaxation and fatigue limit: What about stress relaxation? Is also an ambient temperature phenomenon that can affect a car chassis or is nothing like that? from what I've read, there is a stress value below which the steel does not record damage and can therefore be folded indefinitly. from some tests performed with modern test machines that are able to overcome the "old" cycle threshold it has been discovered that in reality the fatigue limit does not exist, exceeded a certain number of cycles the piece will begin to have fractures even if it has always worked below the fatigue limit. What do you think about it? Does this fatigue limit for steel exist or not? thanks Quote Link to post Share on other sites
Stevebeck002 1 Posted September 18, 2019 Report Share Posted September 18, 2019 Hi, I am agree with ojas(OK) mendapara, If your car is not in use then crossion will play their role in it and after a long time you can see crack with your own naked eyes. Ojas Mendapara 1 Quote Link to post Share on other sites
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