1. Ph.D. Student, Division of Solid Mechanics, Mid Sweden Univ., SE-85170 Sundsvall, Sweden (corresponding author). E-mail: aleksandra.krusper@miun.se
2. Associate Professor, Division of Solid Mechanics, Mid Sweden Univ., SE-85170 Sundsvall, Sweden. E-mail: per.isaksson@miun.se
3. Professor, Division of Solid Mechanics, Mid Sweden Univ., SE-85170 Sundsvall, Sweden. E-mail: per.gradin@miun.se