Study On The Key Factors Of The Influence Of Plantation Chinese Fir Microstructure On Physical And Mechanical Properties

This paper takes 4 cloned plantations of Chinese fir(Cunninghamia lanceolata)in Kaihua County,Zhejiang Province as the research object,and starts with the variation law of the properties of Chinese fir wood within and among plants.Using optical microscope measurement,X-ray diffraction(XRD),micromechanical stretching and other material structure and performance characterization methods,the effects of tracheid morphology,basic density,and tissue ratio on the physical and mechanical properties of Chinese fir plantation were studied.The relationship model between micro structure and physical and mechanical properties is established.The research results are as follows:1.Microstructure study:the tracheid length variation pattern belongs to Pashin I;the tracheid aspect ratio also increases from the medulla to the bark,and there was a certain fluctuation;the tracheid width and the double wall thickness of the tracheid grow with age The increase showed a slight increasing trend,and the change rule was not obvious;the other tracheid morphological indicators showed no obvious change rule in the radial direction.Between clones,at 0.05 level,the difference in tracheid double-wall thickness was extremely significant;tracheid width and tracheid wall-cavity ratio were significantly different;tracheid length and tracheid length-width ratio were not significantly different.The ratio of various tissues of Chinese fir in different clones:the tracheid ratio and thin-walled tissue ratio of sapwood were greater than heartwood,and the ratio of wood rays was less than heartwood.2.Research on physical and mechanical properties:The radial variation pattern of the basic density of Chinese fir is similar,that was,the basic density increases from the pith to the bark.And at the 0.1 level,the basic density of Chinese fir was not significantly different among different clones.Among the different clones of Chinese fir,the crystallinity,MOR and MOE values of the Chinese fir's sapwood were all greater than those of the heartwood,but there was no significant difference between plants and between plants.The radial variation of the tensile strength of micro-slices was significant,and gradually increases with the increase of growth cycle age.At 0.01 level,the intra-plant and intra-plant variation was significantly different,the repeatability is 0.909,which was greatly affected by genetic factors.3.Correlation analysis of anatomical characteristics and physical and mechanical properties:basic density and crystallinity,MOR,tensile strength,tracheid length and tracheid ratio,tracheid width and tracheid wood ray ratio,crystallinity and MOR,Tensile strength,MOR and micro-section tensile strength showed a very significant positive correlation.Basic density and tracheid ratio,MOE,tracheid length and MOR,tracheid width and crystallinity,MOE,tracheid length-width ratio and thin-walled tissue ratio,tracheid ratio and MOE,crystallinity and MOE,MOR There was a significant positive correlation with MOE.Ratio of basic density to parenchyma,ratio of tracheid length to wood ray,tracheid width to tracheid ratio,MOR,tracheid aspect ratio and crystallinity,tensile strength,tracheid wall cavity ratio and crystallinity,MOR,tensile strength,wood ray ratio and MOR,thin-walled tissue and crystallinity,MOR,MOE,tensile strength have a very significant negative correlation;tracheid width and MOE,tensile strength,wood ray ratio and MOE has a negative correlation.4.Establish a logarithmic equation to describe the correlation between tracheid length and basic density of four clones of Chinese fir and tree growth cycle;tracheid aspect ratio,tensile strength along grain and growth cycle age model are fitted by power function equation Good;the double-wall thickness of tracheid trachea of No.?,the width of tracheid trachea of No.IV and the growth cycle age model fit well with cubic equation.The correlation between basic density and mechanical properties is established.The correlation model fits well with linear equations and power function equations,and the correlation between basic density and flexural strength>the correlation between basic density and sheet tensile strength>the correlation between basic density and resistance Correlation of bending elastic modulus.The flexural strength and elastic modulus of Cunninghamia lanceolata fit well with the univariate regression equation,and the correlation coefficient is 0.571?0.703.5.The effects of ten anatomical characteristics of Chinese fir on bending strength,flexural modulus of elasticity,and micro-section tensile strength were analyzed,and the main anatomical factors affecting the bending strength of Chinese fir were basic density,tracheid width,tracheid wall cavity ratio,Tracheid ratio and crystallinity,the model is:y?17.001x1+2.433x3+7.92x6+14.237x7+7.457x10-47.824;bending elastic modulus and basic density of anatomical factors,tracheid length,The tracheid ratio is related to the wood ray ratio,and the prediction model is:y=4006.679-13.52x1+8.44x2+0.504x7-0.17x8;the tensile strength of microsections and the basic density of anatomical factors,tracheid length,tracheid ratio Related to crystallinity,the prediction model is:y=212.83x1+3.84x2+0.46x7+4.13x10-63.06.