I try to mate a coil spring with its supports but I can not make the spring is flexible neither in the assembly file nor the original file .
in the assembly file, the "flexible" feature for spring properties is not appeared !!
in the original file, nothing happens after I click "ok" for "design table" features as I did not .
Correct me if I am wrong, there is no Feature called 'flexible' in SW.
The spring compression or Extension Animation can be achieved by defining a dynamic constrain (e.g. Point A can be moved up and down 5 mm in one axis) and keeping part of the sketch undefined (so that by movement of Point A the sketch and the part associated with the sketch can freely deform/Change).
Sahedul Abedin is correct.
The 'flexible' option you have circled in your picture is for use when inserting a subassembly. If you have an assembly with mates that allows movement (if your parts in the assembly are matted but still allow movement) then when you insert that assembly into a higher level assembly by default it is rigid. If it is rigid the now subassembly will not move in the higher assembly like it does normally unless you select to resolve it as flexible. I hope this helps.
There are a few tutorials on how to make springs in solidworks that appear to stretch and compress but they do not actually function as springs.