505 Saoentn9spm8nron (NM)PEoT [34 2☐ 98 LOAD Displ 030 020 0,10 0.00 -0,10 -0.20 1女23◆ 030 ancecrack line (m) ◆12430-4 0,30 0.10 0.00 100 stance along the crack line (mm) Contact-free measurement techniques appear to be valuable on the other side of it could not be detected.The solution to as a m Using ossible solutio n to another of oted for th ger type 2 join Using contact-fre measu ement techniqucs might be one that a large area was being studied.This meant that some way to study this behavior. areas of the joint could not be studied adequately.especially A great advantage in th ese of a contact-free measure this. rest before performing a test.Ins .This is very useful.for dying the initiation ofacrack.the strain,which nem nd T ork is tha a joint was studied in each case.meaning that possible cracks AB in Sweden for use of the conta tto Mo 505 Fig. 11 Strains perpendicular to grain and shear strains at several stages in the area along the line where the initial crack later occurred. The load displacement re￾sults in the picture at the upper left show which stage is chosen for evaluation Abb. 11 Dehnungen senkrecht zur Faser und Schub￾dehnungen bei verschiedenen Lastzuständen im Be￾reich des später entstehenden ersten Risses. Im Kraft￾Weg-Diagramm im oberen linken Bild sind die ge￾wählten Lastzustände angegeben • Contact-free measurement techniques appear to be valuable tools for calibration in theoretical analyses. They also allow the user to study which parameters are of greatest interest and also make it possible to study non-uniform load distribution within a joint. • It is difficult at present to model the non-linear behavior of timber, a matter which is of interest in studying timber joints. Using contact-free measurement techniques might be one way to study this behavior. • A great advantage in the use of a contact-free measurement system as compared to other measurement techniques is that the user does not have to know which area is of greatest inte￾rest before performing a test. Instead, the user can first carry out a test and then evaluate which areas one should devote greater attention to. This is very useful, for example, when stu￾dying the initiation of a crack, since it allows the strain, which is present prior to the crack being initiated, to be analyzed. • One problem which is obvious here is that only one side of a joint was studied in each case, meaning that possible cracks on the other side of it could not be detected. The solution to this problem would be to use two measurement systems, ac￾ting as a master and slave pair. Then both sides of the joints can be detected at the same instants. • Using two systems could be a possible solution to another type of problem, noted for the larger type 2 joint. The pro￾blem was the rather weak resolution obtained, due to the fact that a large area was being studied. This meant that some areas of the joint could not be studied adequately, especially areas in the close vicinity of the dowels. Using two measu￾rement systems of differing resolution could have avoided this. Acknowledgement This research was made possible thanks to financial support obtained from the Development Fund of the Swedish Construction Industry (SBUF), the Wood Science Program at Växjö University (WDAT￾Wood Design and Technology) and Skanska AB. The work was carried out at Växjö University and at SP Swedish National Testing and Research In￾stitute. Special thanks to GOM GmbH in Germany and Cascade Computing AB in Sweden for use of the contact-free measurement equipment, to Mo-