Non-destructive Testing And Application Performance Of Wood Pallet And Lath

As the most common type of pallets,wooden pallets are widely used in processes of products,handling,transportation and storage.Destructive ways to test pallets and laths’ mechanical properties are used in most companies,which results in waste of resources.In order to reduce the waste and provide technical support,nondestructive testing methods in this study were applied to select materials and test performances of pallets.In this study,PLY(Plywood),LVL(Laminated Veneer Lumber)and New-LVL(New Laminated Veneer Lumber)were dynamically tested by longitudinal resonance nondestructive testing to probe the method’s application in the prediction of elastic modulus and static strength of wood lath.The finite element analysis method was applied to the static test and modal analysis of the New-LVL.Finite element analysis method was carried out on the pallets’ performance test cases.The pallet was made of New-LVL.Through the analysis of the simulation results and the test results,application of finite element method in the performance test of pallets and wood laths is explored.In order to meet the needs of finite element simulation analysis,the elastic constants of wood laths were obtained by three-dimensional optical deformation measurement.The results showed as follows:(1)There is a linear correlation between the elastic modulus,the static elastic modulus and the flexural strength of PLY,LVL and New-LVL respectively,at the level of 0.001.Results of static results shows that,bending strength of LVL is the maximum one and bending strength of PLY is the minimum one.The resonant frequency of the dynamic test results is the same.There is quadratic positive correlation between Resonance Frequency and Dynamic Elastic Modulus.So there is a positive correlation between the resonant frequency and the static bending strength.The above results show that the longitudinal resonance non-destructive testing method can provide some data support for the strength performance prediction of PLY,LVL and New-LVL.(2)The elastic constants of New-LVL are obtained by three dimensional optical strain measurements,which provide the parameters for the finite element analysis.The simulation results are similar to that of the experiments,indicating that the three-dimensional optical test method can be applied to the measurement of the elastic constants of wood-based panels.(3)In the finite element simulation analysis of New-LVL,when the Solid 185 element is selected,the static simulation results are closest to the experimental results.While constraining the position of at ends of laths’ 0.224L,the sixth order mode and the dynamic resonance frequency are similar to the results of dynamic test.When the model is under different constraints and vibration modes are similar,and the resonant frequencies are similar.Therefore,the mechanical properties can be predicted by finite element analysis to improve the stress and deformation of New-LVL.The frequency and mode of the modal analysis provide a reference for the study of the properties of laths.(4)The maximum deformation of the wooden pallets’ static simulation is similar to the test results.The deformation on the diagonal path obtained by the comer drop is slightly higher than the test result.Both the stress and deformation results show that the pallet is not damaged and is the same as the test results.Therefore,finite element analysis can be applied to pallets’ performance testing,and provide technical support for fast and efficient non-destructive testing.