预埋螺母对偏心连接件接合性能的影响
Impact of embedded nut on the joint property of eccentric fittings.
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摘要: 为探索新型嵌入件螺母的可行性,以预埋螺母类型为单一变量,系统研究了T型和L型结构下,5种常用预埋螺母和2种新型嵌入件螺母对偏心连接件接合性能的影响,对比各连接方式的破坏弯矩、刚性效率、破坏特征等。结果表明:1) 各预埋螺母的破坏弯矩:嵌片嵌入件≈柱体嵌入件＞梯形螺母≈内外牙螺母＞尖刺螺母＞四爪螺母＞尼龙胶塞;2) 各预埋螺母的刚性效率:内外牙螺母＞嵌片嵌入件≈柱体嵌入件≈梯形螺母＞四爪螺母＞尼龙胶塞＞尖刺螺母;3)7种预埋螺母的破坏弯矩和刚性系数,T型构件较L型分别高约26.7%、26.8%;4)嵌入件螺母主要破坏特征为三合一连接杆和偏心轮的形变破坏,常用预埋螺母大多为预埋螺母拔出导致的木材撕裂破坏或局部挤压破坏;5)柱体嵌入件螺母T型连接方式中,在仅更换破坏的连接杆和偏心轮情况下,第2次破坏较第1次破坏破坏弯矩仅下降3.1%。预埋螺母类型对偏心连接件破坏弯矩影响显著,嵌入件预埋螺母较常用预埋螺母破坏弯矩大、刚性效率高,可通过更换破坏五金件实现板件的重复利用,具有明显的优势和可行性。Abstract: The objective of this study was to explore the feasibility of two types of new insert nuts by taking inbuilt nut as the single variant. A series of experiments were conducted to analyze the influences of five types of commonly used inbuilt nuts and the two types of new insert nuts on the joint property of eccentric fittings under T and L-shape structures, and the breaking bending moment, rigid efficiency and failure characteristics of the two connection types were compared. Results are as follows: 1) the breaking bending moment of inbuilt nuts are ranked in the order of shim block ≈ cross dowel ＞ screw-in sleeve with flange ≈ screw-in sleeve with hexgon socket and flange ＞ screw-in sleeve with spine ＞ screw-in sleeve with four claws ＞ nylon spreading dowel; 2) the rigid efficiency of inbuilt nuts follows the order of screw-in sleeve with hexgon socket and flange ＞ shim block ≈ cross dowe l≈ screw-in sleeve with flange ＞ screw-in sleeve with four claws ＞ nylon spreading dowel＞ screw-in sleeve with spine; 3) the breaking bending moment and rigid coefficient of the seven types of T-shape inbuilt nuts are 26.7% and 26.8% higher than those of the L-shape, respectively; 4) the main failure characteristics of insert nuts are the deformation of trinity joint lever and eccentric wheel; while for the commonly used inbuilt nuts, the failure mainly includes timber tear and partial crushing triggered by pulling-out of inbuilt nut; and 5) in T-shape connection of cross dowel nuts, under the circumstance of only changing the destroyed joint lever and eccentric wheel, the breaking bending moment of the second time is reduced by 3.1% compared with that of the first time. Therefore, the types of inbuilt nut significantly affect the breaking bending moment of eccentric fittings; compared with commonly used inbuilt nuts, inserted inbuilt nuts are superior in stronger breaking bending moment, higher rigid efficiency and the availability of changing the destroyed hardware to realize the reutilization of plates, showing obvious advantages and feasibility.
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