ABSTRACT

The fact that wood and concrete are two of society’s most common building materials and the widespread domestic/industrial applications of cardboard boxes and paper necessitate an ability to stress analyse components fabricated from these materials adequately. Individual members of wood structures are often connected by bolts and these connections are frequently the weakest element in the structure. While there is a desire to conserve materials, development of improved design procedures has been inhibited by insufficient knowledge of the stresses in the wood surrounding the bolt-loaded holes. Theoretical stress analyses of realistic bolted joints having finite-size members are almost non-existent and reliable numerical analyses of such problems are aggravated by the complicated nonlinear contract conditions between bolt and wood. Such aspects of wood as its poor thermal conductivity reduce the attractiveness of using strain gauges. Optional methods for measuring displacements/strains in paper products are certainly no greater than with wood. The relatively high compliance of paper essentially precludes contacting the paper with or bonding to the paperboard any comparatively stiff transducer. The brittle nature and low tensile strength of concrete motivates the need for a better understanding of this material’s fracture processes. The lack of alternative viable methods for strain/stress analysing cellulosic materials and the advantages such as its full-field nature for fracture analyses render moiré well suited for these applications [1–6].