Thin-walled Structures With Origami Patterns

This dissertation is concerned with three different types of thin-walled structures with origami pattern.The main work is presented in four parts.First of all,a family of origami patterns has been designed for tubes with different profiles.The performances of a series of origami tubes with various configurations subjected to quasi-static axial crushing have been investigated numerically.It is found that travelling plastic hinge lines are responsible for two-thirds of the total energy absorption of a square tube,more travelling plastic hinge lines are activated in a tube,high energy absorption would be achieved.Secondly,a new type of thin-walled tube which has a kite-shape rigid origami pattern pre-folded on its surface is proposed as a potential energy absorption device.The performance of the new device subjected to axial crushing is studied numerically and theoretically.It is found that a new failure mode,referred to as the non-rigid complying mode,can be triggered,and both 29.2% increase in the mean crushing force and about 56.5% reduction in the peak force can be achieved in a single tube design.And a very smooth response curve is also generated in the same design,which makes the new device a good candidate as an energy absorption device.Thirdly,a geometrical description of the waterbomb pattern is given in detail.A folding path through which such a cylinder can be folded rigidly out of a flat sheet of material is then presented.The kinematic analysis of the waterbomb tubes was conducted.Besides,the realistic mechanical behavior of the tube during the mechanism-structures-mechanism transition was consideration,in which the material deformation on the panels will generate.Finally,the mechanical properties of a sheet being cross folded,studying the mechanical properties(stress/strain distributions,energy)of the sheet and examining how these properties change with various shell thickness values,have been analyzed.Based on these studies,we explore several crease design methods and find out the relatively most effective one,which can relieve peak stress due to cross folding.