what is the application, service conditions, process, material choice, material used , properties of material. processes in manufactuing the car suspension?
Sounds like a take home essay question from Auto Shop 101.
Hopefully, the wording in the original post is not the same wording used by the instructor for Auto Shop 101. If it is the same wording, the instructor should attend English 101.
As per other posters, you need to buy a book on automotive suspension systems. The SAE (www.SAE.org)has a library full.
In the short space available, I can only tell you that suspension sytems generally get more sophisticated as the price of the car goes up. But steel and rubber (various kinds) are still the major materials used.
Part of the function of this forum is to point questioners in the right direction, so they can solve their own problems. I can explain to you why the sky is blue in much less space than answering your question.
You can start with you public library’s automotive section and read up on the basics.
Each manufacturer has teams of engineers that work on these issues. They would be the ones to ask. Kind of like asking how a bridge is designed.