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【目的】探索竹材含水率、热压压力、施胶量和热压温度对高频热压成型竹集成材力学性能的影响,并优化高频热压加工工艺获得力学性能较优的竹集成材,为竹集成材高频热压成型提供技术参考。【方法】设计正交试验,采用高频热压加工工艺,以酚醛树脂(PF)为胶黏剂,研究竹材含水率、热压压力、施胶量和热压温度4个参数变量对高频热压成型竹集成材抗弯强度和剪切强度的影响,建立抗弯强度和剪切强度数学模型,分析力学性能最优解。【结果】极差分析表明,热压参数对抗弯强度的影响顺序为热压压力、竹材含水率、热压温度和施胶量,对剪切强度的影响顺序为施胶量、竹材含水率、热压压力和热压温度;主效应分析表明,4级竹材含水率、1级热压压力、1级施胶量和3级热压温度为最佳抗弯强度的热压参数,1级竹材含水率、1级热压压力、2级施胶量和3级热压温度为最佳剪切强度的热压参数;交互分析表明,各热压参数间存在交互作用;方差分析表明,热压压力是影响竹集成材抗弯强度的最重要因素,施胶量是影响竹集成材剪切强度的最重要因素;数学模型分析得出,竹材含水率15%、热压压力2.0 MPa、施胶量260 g·m-~(-2)、热压温度130℃为抗弯强度最优解(168.51 MPa);竹材含水率10.2%、热压压力2.0 MPa、施胶量240 g·m~(-2)、热压温度130℃为剪切强度最优解(263.26 MPa)。【结论】竹材含水率、热压压力、施胶量和热压温度4个参数变量对高频热压成型竹集成材力学性能均有影响,提出的热压参数对竹集成材抗弯强度和剪切强度影响的数学模型,可有效反映热压参数与竹集成材力学性能间的关系,优化高频热压加工工艺生产的竹集成材,其力学性能满足相关标准和使用要求。 相似文献
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不同因素对竹/杨复合规格材性能影响 总被引：1，自引：0，他引：1
基于目前以规格竹条为单元制备竹集成材,存在单元尺寸小、出材率较低、劳动力成本高等问题,研究以无刻痕竹展平板为单元制备新型竹集成材,以有效改善生产效率,降低成本。以尺寸规格化的无刻痕竹展平板和杨木单板为原材料,制备展平竹-杨木-展平竹三层组坯结构的竹/杨复合规格材,运用单因素试验方法,探讨胶合界面方式、胶黏剂和杨木单板厚度三个因素对竹/杨复合规格材抗弯性能、胶合强度以及尺寸稳定性的影响。结果表明:以竹黄面-杨木-竹黄面胶合界面复合方式,采用脲醛树脂胶黏剂与2 mm厚杨木单板制备的竹/杨复合规格材整体性能较优。研究结论为今后新型竹集成材的制备奠定基础。 相似文献
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集成材胶合工艺的研究 总被引：4，自引：2，他引：2
以水曲柳、核桃楸和长白鱼鳞云杉为试验用材,采用水性高分子聚合物异氰酸酯作胶黏剂,以单位压力、加压时间和涂胶量为试验因子进行集成材的胶合试验,并对其胶合性能进行检验。通过试验结果分析,得出较优的胶合工艺条件为：单位压力2．0MPa(水曲柳、核桃楸)、1．5MPa(长白鱼鳞云杉),加压时间为60min．涂胶量为250g／m^2。 相似文献
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影响阻燃胶合板胶合强度因素的研究 总被引：2，自引：1，他引：2
分析了使用BL-环保阻燃剂压制环保阻燃胶合板过程中,热压温度、热压时间、单板浸渍时间和涂胶量对胶合强度的影响,并检测了氧指数、甲醛释放量和含水率。研究表明,使用BL-环保阻燃剂生产环保阻燃胶合板可以达到胶合强度标准,并提出了最佳工艺条件。 相似文献
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Matthew D. Aro Xiping Wang Dwight E. McDonald Marshall Begel 《Wood material science & engineering》2017,12(4):228-235
Laminated strand lumber (LSL) and laminated veneer lumber (LVL) were thermally modified as a post-treatment at 140°C, 150°C, 160°C, 170°C, and 180°C. The tension modulus of elasticity (MOE) of LSL was not significantly impacted by the treatments, with the 180°C treatment group exhibiting the highest tension MOE (11.8?GPa). The LVL also experienced minimal impacts, with the 150°C treatment group having the highest tension MOE (19.4?GPa) and the 160°C treatment group exhibiting the lowest (17.1?GPa). The maximum tensile strength (MTS) of the LSL and LVL significantly decreased with increasing temperatures, with the control and 180°C treatment groups experiencing the highest and lowest MTS, respectively. The lowest MTS for LSL was 10.8?MPa (180°C treatment), which was 70% lower than the controls. The lowest MTS of the LVL was 24.4?MPa (also at the 180°C treatment), which was a 49% decrease compared to the controls. These results suggest that thermal-modification post-treatments minimally impact tension MOE, but can significantly reduce MTS at higher treatment temperatures. Combined with previous work improving the moisture properties and equilibrium moisture content of thermally modified LSL and LVL, it may be possible to optimize the treatment technique(s) to yield products with desirable properties. 相似文献
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The mechanical properties of laminated strand lumber are dependent on the orientation of strands and on the variability of strand alignment in the production process. A model is proposed to predict the in-plane properties and their statistical distributions to allow manufacturers to set target reliability levels for their products. The model is based on the theory of mechanics of composites and assumes homogeneity in each panel layer to allow for multiple-layer panels to be simulated. To verify the model, five types of panels are fabricated using aspen strands with the following stacking sequences: (a) fully-oriented (0° throughout); (b) fully-random (R throughout); (c) random core/oriented surfaces (0°/R/R/0°); (d) random surfaces/oriented core (R/0°/0°/R); and (e) eight oriented layers (0°/+45°/-45°/0°/0°/-45°/+45°/0°). In-plane elastic moduli and ultimate strengths (in tension, compression, and shear) are determined for each panel type. Model predictions match well with experimental results. Properties are shown to be dependent on the degree of strand alignment in each panel type. Using the first-order reliability method, statistical distributions on the properties were predicted and found to compare well with experimental results. A method is proposed for dealing with misalignment of strands based on the von Mises distribution of strand angles to assist manufacturers with production process optimization. 相似文献
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竹层积材的非均匀性与纵向曲翘 总被引：1，自引：0，他引：1
讨论竹材与竹层积材非均匀性和纵向曲翘行为,由于竹篾的几何尺寸和组坯方式决定了竹层积材的非均匀性和随机性,从而决定了其非对称性。参照英国有关标准,测试了竹层压板的纵向曲翘行为。结果表明:材料有可能发生超过结构材要求的纵向曲翘。今后在建立有关标准时应增加相关条目。 相似文献
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薄型单板层积材结构改进的研究 总被引：1，自引：0，他引：1
薄型单板层积材(LVL)可替代锯材,应用于木质门窗构件等轻载结构领域.由于单板全部顺纹组坯,导致产品存在横向翘曲变形的技术问题.为此,尝试采用"部分单板横纹组坯"和"纤维板与单板复合"两种方法进行改进,制造了15 mm厚LVL,包含1～2层单板横纹组坯或1～2层3 mm纤维板.测试结果表明:单板横纹组坯.显著降低了LVL的抗弯性能,但LVL的弹性模量仍能达到单板层积材国家标准中70E级别的要求,而静曲强度甚至超过180E级别优等品的限值;与此同时,改进结构的LVL吸水翘曲变形显著降低.横纹单板越靠近LvL表层,板子抗弯性能降低越显著,而翘曲变形改善越明显.采用纤维板与单板复合制造LVL,纤维板的内结合强度衰减明显,易受破坏. 相似文献
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The rolling shear and longitudinal shear behaviour of laminated Douglas fir veneers was studied using specimens with 15 layers
of 2.5 mm veneers. The rolling shear specimens were constructed such that the 3 central veneers were cross-plies with grain
angle oriented perpendicular to the long axis of the specimen. The other layers were orthogonal to the cross-plies. The longitudinal
shear specimens had a LVL lay-up with the exception of a reinforcement layer of fiber-glass attached to the bottom face veneer.
The fiber-glass layer prevented specimens from failing in bending/tension mode and ensured longitudinal shear failures. Specimens
were subjected to static and cyclic loads in a “flatwise” three point bending configuration. It was found that the rolling
shear failure mode exhibited a higher fatigue resistance than the longitudinal shear failure mode. A damage model that took
the stress history into account was calibrated to the experimental data of each specimen type. Good agreement between model
predictions and experimental results were obtained for both failure modes.
Received 5 November 1997 相似文献
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