Answer: In your system first decide the location where you want to install the spring. Then remove all nearby supports which are not taking load in thermal operating case. Now run the program and the sustained load on that support node is your hot load. The thermal movement in that location is your thermal movement for your spring. Now assume variability for your spring. So calculate
Spring constant = (Hot load × variability)/displacement. Now with spring constant and hot load enter any vendor catalog to select spring inside the travel range.