近海迎风面毛竹林竹材物理力学性质的研究

竹子是集经济、生态和社会效益于一体的优良林种,有着繁殖容易、成林快、一次造林科学经营可持续利用等优点,是区域社会经济发展和生态环境保护的重要资源,其中,毛竹(Phyllostachys edulis(Carr.)H.de Lehaie)为我国所特有的最重要的经济竹种,具有分布广、面积大、利用领域广、效益好等特点。全国现有毛竹林面积720万hm2,其中,毛竹     

毛竹不同种源竹材物理力学性质初步研究

通过对来自福建建瓯试验地16个毛竹种源竹材的密度、顺纹抗压强度、顺纹抗剪强度、顺纹抗拉强度和弦向抗弯强度及其弹性模量等物理力学性质的初步研究,结果表明:竹材物理力学性质在各种源之间存在一定的差异,其中湖南株洲的毛竹竹材物理力学性质比于其它种源的毛竹要好,而安徽霍山的毛竹竹材的物理力学性质较差,测量的各指标中有基本密度、抗剪强度、抗拉强度三项指标都达到最低;竹材密度的大小、抗拉强度的高低随种源纬度的降低而呈降低的趋势,而竹材的抗剪强度呈与之相反的趋势。     

Strength and stiffness capacity utilisation of timber members in roof truss structures

The main objective of this study was to determine which property, of the six strength and stiffness properties used in structural timber design, was the most influential in the design of nail-plated roof trusses. Thirty recently completed nail-plated roof truss designs were randomly selected from three roof truss manufacturing plants and a total of 8 758 individual truss members were analysed for bending stress, shear stress parallel to grain, tensile stress parallel to grain, compression stress parallel to grain and deflection. The mean strength and stiffness capacity utilised of all the different design properties was well below 50% for all of the different dimension classes. Of all the individual strength properties, the mean bending strength capacity utilised per member was found to be the highest. The results of this study can be used for decision support related to wood property evaluation through? out the structural lumber value chain where roof truss members are the end products.     

竹节对竹材力学强度影响的研究

本文对毛竹和刚竹的带节材与不带节竹材的主要力学性质研究表明,带节竹材的抗弯强度、顺纹抗压、抗剪、抗拉强度和冲击韧性都有一定程度降低的趋向,但抗劈开强度和横纹抗拉强度却有明显提高。影响竹材力学强度的主要因素是维管束数量、维管束排列方向及维管束中纤维的力学强度,了解这些规律,对复合材料的结构仿生有重要参考作用。     

改性辐射松木材物理力学性能研究

研究了辐射松树脂浸渍材与热空气热处理树脂浸渍材、热压热处理树脂浸渍材的物理力学性能,为后续辐射松改性处理和加工利用提供参考。结果表明:相对于未处理材,浸渍处理提高了木材的密度、尺寸稳定性、力学性能;相对于浸渍材,热处理可进一步提高尺寸稳定性,但一定程度降低了力学强度。     

KY-FW阻燃剂对木材力学性能的影响

采用杉木和泡桐为试材,对经过KY-FW阻燃剂处理的木材与未经处理的木材进行对比研究,分析KY-FW阻燃剂对木材力学性能的影响.结果表明,木材经KY-FW阻燃剂处理后,除冲击韧性降低外,其它主要力学性能指标(如抗弯强度、顺纹抗压强度及硬度)都有所提高.KY-FW阻燃木材的力学性能达到了一级水基型阻燃剂标准规定的相应指标.     

苦竹竹材化学与力学性质的相关性分析

测定了1-5年生苦竹秆上、中、基3个部位的顺纹抗压强度、顺纹抗拉强度、弦向抗弯强度租化学组成，并对其进行了相关分析，结果表明：顺纹抗拉强度与各化学组成均为显著相关，顺纹抗压强度与纤维素的质量分数达显著相关，木质素和苯-醇抽提物的质量分数与力学强度为正相关，纤维素、灰分、热水抽出物、1％NaOH抽出物的质量分数与力学强度为负相关。     

Strength grading of Norway spruce structural timber: revisiting property relationships used in EN 338 classification system

Solid timber for structural applications has to be strength graded prior to its use. In order to remain economic the grading process usually focuses on the most important physical and mechanical properties: density, modulus of elasticity (MOE) and bending strength. Based on respective limits given in standards, the timber is assigned to strength classes. Additional mechanical properties such as tensile and compression strength parallel to the grain are derived from the basic property values by empirical relationships. The objective of this study was to review some of these property relationships based on recently compiled large data sets as a contribution for a future revision of the grading standards. Based on mechanical tests of Norway spruce structural timber with different cross-sections, the following characteristic values and property relationships were evaluated: (a) strength and MOE in bending, (b) in-grade characteristic values of bending strength, bending MOE and density, (c) relationship of characteristic values of tension and compression strength parallel to the grain with respect to the corresponding characteristic value of bending strength, (d) ratio of fifth percentiles and mean values of density and MOE, as well as (e) the ratio of MOE in bending, tension and compression. Mechanical tests were accompanied by measurements of density and ultrasonic wave speed. Resulting dynamic MOE was partly used as an indicator of timber quality.     

Quantitative Analysis on Measure Results by Resistograh for Wood Decay of Ancient Architecture

INTRODUCTION The main body of ancient architecture is wood construction in China, and the main bearing components of the buildings usually use timber, such as pillar, beam, purlin, crossbeam and rafter. Timber is a kind of biomaterial and will be damaged by fungal attack or insects after long time use, which will cause wood frames destroyed ultimately. Timber decay not only exists in its surface, but also usually begins with the inner of wood. It is therefore imperative to consider using …     

COMPARATIVE STUDY OF WOOD PROPERTIES BETWEENWHITE WOOD OF DAHURIAN LARCH AND MONGOLIANSCOTCH PINE

DahurianlarchandMongolianscotchpinearetwomajorconunerciaIconilbroustTeesinDaxing'anlingForesnyArea.Itisob-viousthattbcwoodproPertiesandworkability'ofthetWoplantsarecompletelydifferent.Butlnrecert'years,ltlsfoundthattherearetwodiffer':nttypesinparameterofwood'scolour.phy'sicalandmechanicalproPertiesandwork-ability'inDahurianlarch,namelyredwoodandx"hite..od.l']Andthepropertiesofwhite`voodaresligl1tlyyellow-white,medianweightandhardness,goodinworkability'andLard-ness,goodinwodability'anduneas…     

钩梢对5年生毛竹竹材物理力学性质的影响

毛竹(Phyllostachys edulis)秆形通直、材性优良,是利用范围最广、经济价值最大的竹种(刘亚迪等,2008);但同时因毛竹秆高大、枝叶繁茂,是受风雪灾害影响较大的林种之一(肖本权,2003)。2008年初,我国南方遭受了严重的雨雪冰冻灾害,涉及湖南、安徽、浙江、江西等19个省(区、市),受灾森林面积1860万hm2(祝列克,2008),受灾中心区域为毛竹的主分布区,占我国毛竹林面积的70%以上。据统计,全国竹林受灾面积约400万hm2,其中80%为毛竹林(李潇晓,2008)。在竹林培育中,为应对雨雪冰冻灾     

15年生巨尾桉人工林木材物理力学性质的研究

为了更好开发利用15年生巨尾桉人工林木材,本研究以广西南宁市树木园15年生巨尾桉(Eucalyptus×E.urophylla)人工林木材为研究对象,对其物理以及力学性质进行了测试、分析。结果表明,15年生巨尾桉属中密度等级材,体积干缩系数小;抗弯强度,抗弯弹性模量、顺纹抗压强度和冲击韧性分别为83.9、12790、44.2、65KJ/m2,对应的强度等级分别为2级、3级、1级、2级;端面、弦面和径面的硬度分别为68.9、51.3、55.1MPa,其中端面硬度已经达到了4级标准,弦面和径面的硬度也达到了三级标准。木材综合强度为128.1MPa,属高强度树种;木材的综合品质系数达到了191.2GPa,属于低等级材。     

Strength properties and effect of moisture content on the bending and compressive strength parallel to the grain of sugi (Cryptomeria japonica) round timber

Static bending tests and compressive test parallel to the grain of sugi (Japanese cedar, Cryptomeria japonica) green round timber were conducted to confirm whether its strength would satisfy the referenced strength determined by the Construction Ministry. The strength of green round timber and air-dried round timber were compared for bending and compression parallel to the grain. The strength change ratio in response to a 1 % change in the moisture content of round timber was compared with that of small clear specimens and timber. The results revealed that a 5 % parametric tolerance limit of bending and compressive strength parallel to the grain satisfied the referenced strength, even when using green round timber. The average strength of air-dried round timber was higher than that of green round timber, in both bending and compression parallel to the grain, with significant differences indicated at a 5 % significance level. The relation between the cross-section area that includes round timber, timber and the small clear specimens, and the strength change ratio in response to a 1 % change in moisture content change was fitted to a logarithm curve. Thus, the size of the specimen was considered to affect the strength change ratio.     

Effects of impregnation and heat treatment on the physical and mechanical properties of Scots pine (Pinus sylvestris) wood

Wood modification, of which thermal modification is one of the best-known methods, offers possible improvement in wood properties without imposing undue strain on the environment. This study investigates improvement of the properties of heat-treated solid wood. Scots pine (Pinus sylvestris) was modified in two stages: impregnation with modifiers followed by heat treatment at different temperatures. The impregnation was done with water glass, melamine, silicone, and tall oil. The heat treatment was performed at the temperatures of 180°C and 212°C for three hours. The modified samples were analyzed using performance indicators and scanning electron microscope micrographs. The mechanical and physical properties were determined with water absorption, swelling, bending strength, and impact strength tests. All the modifiers penetrated better into sapwood than hardwood; however, there were significant differences in the impregnation behavior of the modifiers. As regards the effect of heat treatment, generally the moisture properties were improved and mechanical strengths impaired with increasing treatment temperature. In contrast to previous studies, the bending strength increased after melamine impregnation and mild heat treatment. It is concluded that the properties of impregnated wood can be enhanced by moderate heat treatment.     

红壳竹人工林竹材物理力学性质的研究

测试了红壳竹人工林竹材的物理力学性质。结果表明：竹龄对红壳竹竹材的物理力学性质有显著的影响；竹材的径向、弦向、体积全干缩率随竹龄增加逐渐减少；基本密度、顺纹抗压强度、顺纹抗拉强度和抗弯强度都随竹龄增加而提高，至5－6年生强度稳定在较高的水平上，竹午由下至上，含水率、体积全干缩率逐渐减少；维管束密度、基本密度及力学强度相应提高。     

西南桤木木塑复合材料的研究

采用乙烯基类系列单体——丙烯腈(AN)、甲基丙烯酸甲酯(MMA)、丙烯酸(AA)三元共聚单体注入西南桤木木材中，制成新型的高分子复合材料(AMA—WPC)。单体的注入用满细胞法，聚合用热引发法，并采用添加氯化锌对木材细胞壁进行活化等工艺对木塑复合材进行了研究和分析。实验样品按照国标GBl927—1943有关规定进行测试，并结合傅立叶红外光谱和扫描电镜探讨了各因素对AMA—WPC材料接枝率及性能的影响。结果表明：改性后西南桤木木塑复合材料具有优异的物理、力学性能。与素材相比较，AMA—WPC的密度提高了59．8％，顺纹抗压强度提高了76．7％，抗弯强度提高了90．4％，抗弯弹性模量提高22．2％，端面硬度提高102．3％，径面硬度提高153．6％，弦面硬度提高152．2％，吸水率降低56．7％，湿膨胀率降低19．0％。     

湿地松与马尾松人工林木材物理力学性质的比较研究

通过对湿地松和马尾松人工林木材物理力学性质的测定和比较分析,结果表明:湿地松人工林木材密度、干缩系数和除冲击韧性以外的力学强度均稍大于马尾松人工林木材,而冲击韧性则恰恰相反.经差异显著性t检验表明:湿地松和马尾松木材物理力学性质指标中顺纹抗压强度、抗弯强度、弦面顺纹抗剪强度和冲击韧性差异极显著,气干密度、基本密度、径面顺纹抗剪强度和端面硬度差异显著,除此之外的其余指标差异不显著.     

Evaluation of quality indexes of bending performance and hardness for hardwoods

The mechanical properties of 613 small clear specimens of 35 species (11 ring-porous hardwoods, 19 diffuse-porous hardwoods, and 5 softwoods) were evaluated. The aim of the study was to examine indexes of wood quality that are easy to measure and that exhibit a high correlation with bending performance and hardness that are essential properties of hardwood products. The modulus of rigidity, dynamic modulus of elasticity, bending properties (modulus of elasticity, modulus of rupture, stress at the proportional limit, absorbed energy, Tetmajer’s modulus), dynamic energy absorption by an impact bending test, compressive strength parallel to the grain, shear strength, partial bearing strength, and Brinell’s hardness were measured. A high correlation was found between dynamic modulus of elasticity and static modulus of elasticity. Bending stress at the proportional limit was found to be approximately equivalent to the compressive strength parallel to the grain. Static energy absorption correlated with dynamic energy absorption. Tetmajer’s modulus was found to be closely related to the ratio of the initial stiffness within the elastic range to the secant modulus at the maximum load. A high correlation was observed between Brinell’s hardness and partial bearing strength. The difference in the regression coefficients obtained for these correlations between the species groups was small. Part of this study was presented at the All Division 5 Conference of IUFRO, Taipei, October 2007     

重庆市梁平县刺楸材性研究

对刺楸木材的理化性质进行了研究,分析了刺楸的材性。结果表明：（1）刺楸木材的绝干密度为0．57g／cm^3,差异干缩为0．68,说明刺楸的干燥性能较好;（2）根据木材力学性质划分方法,除抗弯弹性模量属低级外,抗弯强度、顺纹抗压强度、综合强度、冲击韧性,均为中等;（3）刺楸的综纤维素含量为82．20％,克见纤维素为43．86％,木素含量为17．6％,符合造纸工业的要求;（4）根据刺楸的理化性质,刺楸可作为优质家具材料、装饰材料、造纸原料。     

人工林杉木木材力学性质对高温热处理条件变化的响应

以人工林杉木为试材,分别用空气和菜子油为介质,在温度为180,200和220 ℃对其分别热处理1,3和5 h,研究试材的抗弯强度(MOR)、抗弯弹性模量(MOE)、顺纹抗压强度、表面硬度对高温热处理条件变化的响应,同时对处理材的主要化学成分进行分析,用扫描电镜对处理材横切面微观结构进行观察.结果表明:人工林杉木试材的4种主要力学性质对不同条件热处理的响应程度不同.无论是空气热处理还是油热处理,试材的MOR,MOE,顺纹抗压强度与对照比有不同程度的降低,且随处理温度升高、时间延长,下降幅度增大,相比于时间,温度的影响更显著;180 ℃热处理1,3和5 h时,试材的MOR,MOE与对照比未发生明显变化(降幅在3%以内),而顺纹抗压强度则明显低于对照,两介质中降低幅度分别在3.29%～9.58%和3.89%～7.18%;200 ℃以上处理时,不同时间处理的3种主要力学性质不仅显著或极显著低于对照,且各性质问的差异也达显著或极显著水平;对硬度的测试结果表明:180 ℃热处理时,试件的径面硬度和弦面硬度均随时间的延长而增大;200 ℃热处理3 h时,试件的硬度达最大,与对照差异达显著水平;随后热处理试件的硬度开始降低,220 ℃热处理5 h后试件的硬度又明显低于对照.在隔氧的油介质中进行热处理,4种主要力学性质的变化程度低于空气介质处理材,当温度高于200 ℃时,两介质处理间的差异达显著水平.而热处理过程中木材主要化学组成与横切面微观结构变化的差异,反映了4种主要力学性质对不同条件热处理时表现出的响应差异.