چكيده به لاتين
As the only renewable structural material, the importance of wood and wood-based products is undeniable. The present study aims to present an understanding of the properties and behavior fracture in processed wood. Accurate understanding of fracture behavior of wood not only saves valuable time and financial resources but also prevents loss of life and financial resources. While fracture in modes I and II has been extensively studied, literature review reveals a clear paucity of experimental investigation of mixed mode I/II, fracture in many wood products including medium density fiberboards and particle boards despite the frequent occurrence of mixed mode I/II fracture. In the present work, the behavior of medium density fiberboard, high density fiberboard, particle board, oriented strand board and plywood is studied by performing tensile tests. Subsequently, the isotropy property which determines material behavior is analyzed After extraction of mechanical properties such as tensile strength, Young’s modulus and Poisson’s ratio. Demonstrating significant advantages over other fracture specimens, the semi-circular specimen which has unfortunately received less attention, was used to carry out the bending fracture test on the mentioned processed wood products after their isotropy behavior was determined. One of the main challenges in the bending test is crushing under applied pressure. In the present study an effective method is presented to resolve the mentioned issue. The obtained results indicate that the maximum circumferential strain criterion can accurately predict the mixed-mode fracture response of the wood products under consideration. Moreover, the fracture toughness as well as crack initiation angle were obtained for the medium density fiberboard and the particle board and were theoretically analyzed. Finally, statistical analysis of fracture in a number of fiberboards and particle boards representative of the entire statistical population, is conducted. The statistical study was based on approximation of fracture toughness in mode II using that under mode I.
