共查询到17条相似文献,搜索用时 15 毫秒
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根据中国、日本和美国的外观分等标准对落叶松试材进行了以强度为基础的外观分等,并对试材进行了振动检测,分析比较了三国不同外观分等结果与振动检测的相关关系。 相似文献
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根据中国、日本、美国的外观分等标准对落叶松试材进行了以强度为基础的外观分等,然后对试材进行应力波检测,分析比较不同外观分等结果与应力波检测的相关关系。 相似文献
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以落叶松锯材为试验对象,依据日本JAS 235<构造用集成材日本农林规格>中外观分等的相关规则,对人工林落叶松锯材进行了以节子为检量对象的外观分等并对分等后的锯材进行了弯曲破坏试验,分析比较了外观分等结果与其弯曲破坏检测结果的相关关系. 相似文献
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以落叶松锯材为试验对象,依据美国材料试验协会ASTM D245中外观分等的相关规则,对人工林落叶松锯材进行了以节子为检量对象的外观分等,并对分等后的锯材进行了弯曲破坏试验,分析比较了外观分等结果与其弯曲破坏检测结果的相关关系. 相似文献
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北美规格材目测分等概述 总被引:1,自引:1,他引:0
目测分等方法是北美一种很重要的锯材分等体系, 即依据目测分等规则通过肉眼观测方式测定木材的缺陷状况进而确定规格材的材质等级。因此, 对木材缺陷与材质等级之间关系的正确把握以及对分等规则的正确应用, 是对规格材进行科学、正确分等的基本要求。合理地依据目测分等规则划分规格材等级, 不仅可以使规格材生产厂家的经济效益最大化, 而且有利于规格材产品使用性能的充分、合理发挥。经过目测分等的规格材具有客观的力学性质以及外观质量等级, 可以为其作为结构用材使用时提供科学的依据。直到今天, 目测分等方法依然是北美进行规格材分等的主要分等方法和基础。文中介绍了北美目测分等方法的发展、原理、意义以及世界上其他一些国家和地区的目测分等标准, 并对中国目测分等标准与北美目测分等规则进行了比较, 希望对完善我国的目测分等规则有所启示。 相似文献
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介绍了一种基于虚拟仪器技术的规格材应力分等测试系统.该系统在LabVIEW编程环境下完成对信号的采集、显示及数据分析,实现对试件力学性能的检测,并成功应用于木结构规格材的应力分等试验中,取得较满意效果. 相似文献
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It is well known that the presence of knots in structural lumber is one of the most important strengthreducing factors. For practical purposes, visual grading including knot restriction is an effective method for nondestructive evaluation of strength. Edge knot restriction for not only visually graded lumbers but also mechanically graded lumbers is specified in the Japanese agricultural standards for glued laminated lumber. We conducted experimental studies on differences of tensile strength distributions between mechanically high-grade and low-grade Japanese larch (Larix kaempferi, carriere) lumbers daily used for manufacturing glued laminated timbers in Nagano, Japan. We then examined the additional visual grading of mechanically graded lumbers for nondestructive evaluation. We visually graded the prepared mechanically graded lumber by focusing on the knots' area ratio of grouped knots. We confirmed that the higher visual grade related to the stronger tensile strength, similar to our present knowledge; but the effects of knot restriction were reduced when the length of the lumber increased in view of nonparametric 5th percentiles of tensile strength. The differences in the strength/elasticity ratio between mechanically high-grade and low-grade lumber were negligible. It was clear that the length effect on the ratio in visually graded high-grade lumber was smaller than that of visually graded low-grade lumber. It was thus concluded that knot restriction should have little effect on the tensile strength of mechanically graded lumber. 相似文献
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GUO Wei REN Haiqing YIN Yafang Research Institute of Wood Industry Chinese Academy of Forestry Beijing P.R.China 《中国林业科技(英文版)》2007,6(2):36-40
As one of the most important plantations, Chinese fir has drawn more and more attention from domestic wood researchers. And as the development and increasing of plantation resource of Chinese fir, research and development of the product will become a hot point. In this paper, we chose 1 571 pieces of structural lumbers from 4 areas to research grading. After sawing, drying and dressing, the lumbers were separated into 3 main grades by GB50005-2003 Code for Design of Timber Structures, namely SS, No. 1 and No.2. The conclusions are that knot as the maximum strength reduced defect (MSRD) is a main character in the lumber, the visual quality of Fujian structural lumbers is polarized, and the applicability of visual grading to the lumber is poor, so we hold the point that we should adjust the grading rules to gain a better grading result. 相似文献
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介绍"十一五"国家科技支撑计划"高强度结构材加工利用技术"课题中,对我国主要的商品林树种之一——落叶松,在规格材的优化加工、分级、无损检测、强度性能测试及木构件连接等关键技术研究方面,取得的重点创新成果。这些成果开创性地解决了我国利用国产资源加工结构用规格材的关键性和共性技术问题,并且为我国落叶松资源的高效利用,提供了新的技术途径。 相似文献
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原木等级及径级对规格材质量及出材率的影响 总被引:1,自引:1,他引:0
选用不同径级和质量等级的兴安落叶松原木,采用毛板下锯法和四面下锯法加工规格材,并检测分析了不同等级规格材的出材率。结果表明,原木径级在26~28cm时,规格材出材率较高;原木的等级与径级,及下锯法与原木径级交互因素,对规格材的出材率有显著的影响。要提高规格材出材率,应根据规格材尺寸优化匹配各因素。 相似文献
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通过NS(一种化学药剂)改性落叶松材和素材在相同干燥基准下干燥速度和干燥质量的对比试验,研究了Ns改性对落叶松材干燥性能的影响。结果表明:NS改性可显著改善落叶松材的干燥性能,40mm厚板材平均干燥速度可提高48%以上,各项干燥质量指标均高于国家二级标准,完全可满足家具等生产的需要。 相似文献