Study On The Optimize Design For Parameters Of Screw Thread Used In Glued Laminated Bamboo And The Mechanical Property

Screw is one of the splice forms in the application of Glued Laminated Bamboo. Theoptimize design for the parameters of screw thread used in Glued Laminated Bamboo is based onthe parameters in the orthogonal experiment of this thesis, and the strength impact for the GluedLaminated Bamboo screws connection type is analyzed respectively in the following elements:the directional hole diameter size, the depth and direction of wringing, times of dismounting.Some conclusions can be drawn in the following:(1) After pulling out substrate, the damage extent of the screw deformation and the changesin the thread angle is relevant. The20°thread angle' change is greater than the30°, for40°,50°and60°, thread deformation is not obvious, or even no change. Based on the results of this test,thread parameters for40°angle,1mm height and2mm pitch is fitter for Glued LaminatedBamboo.(2) Pilot hole diameter have an obvious effect on the strength of application.There is a samelaw in parallel fiber direction and perpendicular fiber direction. For10mm screw diameter,ultimate pullout capacity have risen when pilot hole diameter changed longer which is between8.0mm and8.6mm, it is the biggest for8.6mm,and then it begin to decreaseing. When the pilothole diameter is8.6mm the ratio of stab dip and screw thread height is0.7, it is suitable for theconnection type of screw used in Glued Laminated Bamboo.(3) Ultimate pullout capacity of screw has risen when wringing changed deeper, it is thepositive correlation between them, and it can be shown for a linear function: y=358.90x-558.24,the correlation coefficient is R=0.99, there is a closer relations.(4) The biggest ultimate pullout capacity of perpendicular fiber direction is10305.01N, andthe parallel fiber direction is8058.34N, the ratio is78.20%. For displacement curve, the loaddecreases suddenly after the peak in perpendicular fiber direction. The parallel fiber directionconnection type of screw used in Glued Laminated Bamboo is worse, the brittleness is high andthe toughness is low.(3) Ultimate pullout capacity of screw has decreased when the dismounting time changedmore, it is the negative correlation between them, and it can be shown for a linear function: y=-65.76x+9550.10, the correlation coefficient is R=-0.98, there is a closer relations.