The Study Of Mechanical Stress Grading Equipment On Bending Test And The Detection Experiments Of Dimension Lumber Elastic Modulus

The mechanical stress grading method is effective for detecting dimension lumber elastic modulus. Foreign mechanical stress grading method used to analyze the dimension lumber grading has obtained the widespread application. Domestic research in this area started late. Related technology accumulation is also relatively weak. Dimension lumber of mechanical stress grading and the elastic modulus of the detection experimental study compared with foreign countries have a larger gap. Heilongjiang Institute of Wood Science in cooperation with Northeast Forestry University assumed special scientific research projects funding for forestry public welfare sectors of the State Forestry Administration. The research on the structure bearing capacity detection technology of engineering wood composites (Project number: 201304514). For the purpose of detecting dimension lumber dynamic elastic modulus, this research based on bending method design a continuous eccentric pressure roller mechanical stress grading machine. Explore the relationship between dimension lumber dynamic elastic modulus and static elastic modulus. Achieve dimension lumber elastic modulus detection online to determine the strength grade of dimension lumber.Based on the foreign mechanical stress grading technology studies, analyzing the detection principle and components function of mechanical stress grading machine on bending method, the overall design scheme of mechanical stress grading machine on bending method is proposed. Creating dynamic elastic modulus formula of dimension lumber on eccentric structure load. Study a new mechanical stress grading machine on eccentric structure pressure roller and control system. Apply for a invention patent and authorized a utility model patent.Combining detection principle with design requirements of mechanical stress grading machine. Structural design and mechanics analysis for mechanical stress grading machine main executive member of eccentric pressure roller. Use Solidworks modeling, generate Parasolid files, import ANSYS finite element analysis software, eccentric pressure roller axis static analysis under maximum pressure to verify the reliability of the maximum pressure. Using the ANSYS finite element analysis software Workbanch module, the eccentric platen roller shaft detection system transient dynamic analysis, research testing process of extrusion pressure, friction, stress and other parameters and distribution, verification eccentric pressure roller axis detection system architecture design is reasonable and safety. At the same time, other major components are designed.Completed the elastic modulus testing and experimental analysis of larch dimension lumber. By the mid-point bending load method of mechanical stress grading machine, testing larch dimension lumber specimens dynamic elastic modulus, obtaining dynamic modulus of elasticity Es experimental data. By three-point bending method load universal mechanical testing machine, testing larch dimension lumber specimens static elastic modulus, obtaining static elastic modulus Ep experimental data. Established linear regression equation to study the dynamic elastic modulus Es and static elastic modulus Ep correlation. Experimental results show that the dynamic elastic modulus Es measured by mechanical stress grading methods and static elastic modulus Ep measured by three-point bending has a good correlation, correlation coefficient 0.86, and 0.01 levels significantly.The project research results for further research dimension lumber grading testing and promotion of dimension lumber mechanical grading provides theoretical support and technical assurance. Mechanical stress grading testing technology with high degree of automation, can achieve continuous batch testing, extremely applicable to practical industrial applications.