Wood Elasticity And Viscoelasitic

Elasticity is the most solid materials in low-stress deformation demonstrated by a mechanical behavior.The elasticity of solid obey Hooke's Law,wood vertical force when the stress and strain in the ratio limit is obeyed Hooke's Law.The wood elastic constants is the indicators of wood,but also is the wood structural design and materials of wood-taiwan's important design parameters.Wood is a high degree of anisotropy materials, tensile and compressive modulus of elasticity,can be seen as similar to the same.The wood structure the organization decided to its anisotropy,different species of its relative bending modulus and tensile and compression are also different.With the development of modem science and technology,measuring the wood of modulus way more and more,and more and more advanced.In this experiment,using the measurement instrument of law and extended,this study measured Picea jezoensis,Poplar,Larch,Castanopsis hystrix four woods of the 12 elasticity factors,type face,and Hyun-track section of section three Poisson's ratio.First,it is necessary to determine the tensile,compression and bending modulus of the size,power consumption measured by the pilot and extended for two methods on Picea jezoensis,Poplar,Larch,Castanopsis hystrix four different species of timber,in the same Conditions down a stretch,compression and bending modulus of elasticity comparison.Measuring and testing by four of the 12 timber elastic constants.And with orthotropic material limitations to verify.Viscoelastic is an important feature in wood polymer material.The perfect Solid elasticity obey Hooke's Law,that is,in a very deformation,stress proportional to the strain, the ideal viscous liquid obey Newton's law,that is proportional to the stress strain rate.The wood polymer materials produced by the external changes between solid elasticity and the viscous liquid.Viscoelastic is the most striking features in mechanical properties of polymers,so to understand viscoelastic phenomenon,not only on the structure of wood polymer an important branch,but also master of wood and other key mechanical properties of polymers.This experiment is in the basis of viscoelastic material static to test the creep of simulated wood materials,and proposed a new method to study the dynamics of wood viscoelastic mechanical properties,that is,solid standard linear model to describe the nature of viscoelastic,through forced resonance way in a resonant frequency bands under the complex modulus and viscoelastic parameters ER,τ_σ,τ_ε,and analysis of the viscoelastic material loss to the damping.Experiments show that:1.Wood is a high degree of anisotropy materials,tensile and compressive modulus of elasticity,can be seen as similar to the same.Different species of its relative bending modulus and tensile and compression are also different.2.Electricity measurement method of testing wood elastic constants is a well-established, the test measured data,the coefficient of variation was less than 20 percent.3.Static load of wood,the anti-instantaneous elastic deformation capacity and the strain that growth lags behind the growth of stress.With the relaxation time and test specimen span of the increasing trend of growth that material in the role of static load,short-term period of viscous creep lower. 4.Static load under the constant stress creep and dynamic nature of the stress under the viscoelastic nature not the same.5.Wood materials showing a more elasting and less damping,damping coefficient is lower...