Lap Joint Essay

COMPARATIVE STUDY ON COLD-FORMED LAP JOINT SHEAR TEST

Author 1, author 2, and author3

ABSTRACT

This paper presents an analytical method to find out the deformation range of cold formed lap joint connected with self drilling joint. Based on the deformation range obtained stiffness of the joint can be determined and it has been compared with experimental values. The study is limed to self drilling joints. Stress-strain behaviour, load deflection datas are obtained by the abaqus modeling. Three different lap joints are modeled in abaqus with different strip thickness. Comparison of the load displacement curve has been plotted to verify the connection behaviour on lap joint. The failure modes found in experimental test was satisfactory

It is also necessary to study the behaviour of the connectors such as gusset plate under localized forces. In order to examine the structural behaviour of the fasteners and the connectors, a finite element analysis 3 dimensional shell elements with material, geometry and preferred boundary condition have modeled using Abaqus/CAE/6.12-1

FINITE ELEMENT ANALYSIS

The finite element analysis of Lap shear test has been modeled as 3-D deformable shell element. The element is defined by eight nodes having three degrees of freedom at each node, translations in the nodal x, y, & z direction. They use linear interpolation in each direction and hence are called linear elements or first order elements. A Cold form steel strip of length 130mm and width 40mm is connected by a 4.8mm screw, which is modelled as 3D deformable Solid element. Fig 1. Lap joint

The material modeling simulates the properties of cold form steel, having a ductile behaviour compared to hot-rolled steel. The material is elastic isotropic of young’s modulus 210000 N/mm2 and poissons ratio 0.3; the stress strain behaviour of steel strip is given in table 1.3D solid screw is assigned with 200000 N/mm2 which has the behaviour of hardened steel and a poisons ratio of

Plates with thicknesses 3mm-2mm, 3mm-2.5mm, 2.5mm-2mm. the joint is safe against the failure load and the modes of failure match reasonably well. Typical failure modes for these types of joints are: Tilting and pull out of the fastener from the bottom steel sheet (ductile failure mode), tearing of the thinner sheet (brittle failure mode). The experimental curve is useful in performance based design. But the design process is ductility based and hence the present conclusion is justified. Fig 4. Load displacement curve for 3-2mm plate Fig 5. Load displacement curve for 3-2mm plate Fig 6. Load displacement curve for 3-2mm plate

CONCLUSIONS

This paper presents a comparative study on cold form strip lap joint using self drilling screw. The deformation characteristics predicted by Abaqus modelling is closely matches to the experimental studies.

REFERENCE

K.F. Chung, H.C. Ho [2005] “An investigation into deformation characteristics of lapped connections between cold formed steel Z sections “steel structures 5(2005) 23-32.

Pekoz, T. [1990] “ Design of cold-formed steel screw connections “Tenth International Specialty Conference on Cold-formed Steel Structures St_ Louis, Missouri, U.S.A., October 23-24, 1990

L. Fiorino et al.” Experimental tests on typical screw connections for cold-formed steel housing” Engineering Structures 29 (2007)