i am trying to apply strain gauge on springs
i need some extra information
1. is it specific direction for adding rosette ?
2. is it any formula to choose size of rosette due to wire size ?
3. is there other method to measure shear stress on springs(exprimental ) ?
4. is there any formula to compare inner surface stress with outer surface stress of springs wire ? ( i know k factor but it just gave me max stress not min for outer surface )