Geometrical Parameters Of Joints Research Articles

Effect of material combinations on mechanical properties of flat bottom riveted joint

Flat bottom riveting is a newly developed joining technique. Since the bottom surface of joint is flat, the joint can be applied in areas that need a high degree of smoothness. This article investigated the effect of material combinations on mechanical properties of joints. Four material combinations which involved two kinds of aluminum alloy were produced. Cross sections of joints were observed by metallographic microscope and geometrical parameters of joints were measured. It was found that material combinations exerted significant influence on the geometrical parameters of joints. When the bottom sheet remained the same, with the increase of top sheet hardness, the interlock thickness of joint decreased, while the neck thickness of joint increased. Tensile and shearing tests were conducted on joint to obtain the tensile load and the shearing load of joint. The absorbed energy of joint in shearing test was calculated. Results showed that when joining materials with different hardness values, the joint with high hardness sheet on the top exhibited higher static load than the joint with high hardness sheet on the bottom. In tensile tests, 1060–5052 joint failed in the manner of neck fracture, while other joints failed in the manner of button separation. In shearing tests, 5052–1060 joint failed in the manner of button separation, while other joints failed in the manner of neck fracture.

Investigation on clinch riveting process with different material combinations

Clinch riveting is a new joining process originating from clinching. The presence of rivets greatly enhances the shearing load of joints. However, conventional rivet is deformable, which may increase technological intricacy consequently. In this article, clinch riveting with rigid rivets was proposed, and the effects of sheet material combinations on the mechanical properties of joints were researched. Four sheet material combinations, involving two kinds of aluminum alloy (AA5052 and AA1060), were utilized to produce the clinch riveted joints. The joining quality was evaluated in four aspects: tensile load, shearing load, failure mode, and absorbed energy in shearing tests. Tensile and shearing tests were implemented to obtain the static load of joints. Results showed that both sheet materials and the geometrical parameters of joints were key factors determining the mechanical properties of joints. During the joining of different materials, the joint with a high-strength sheet on the top exhibited greater static load and absorbed energy than the joint with a low-strength sheet on the top. Neck fracture, button separation, and mixed failure could be observed in tensile tests. In shearing tests, all joints failed at the neck parts.

Experimental investigation of high impact polystyrene/metal self‐piercing riveted joint

AbstractSelf‐piercing riveting was adopted to join high impact polystyrene (HIPS) and metal sheets which had huge difference in material properties. Three kinds of metal sheet (AA1060, AA5052, and HC340LA) were joined to HIPS sheet. The effect of polymer sheet thickness on mechanical properties of joints was investigated. The static loads of joints were measured in tensile and shearing tests. The failure modes of joints were analyzed. The cross sections of joints were observed by metallographic microscope. Results showed that self‐piercing riveting could effectively join HIPS and metal sheets when polymer sheet was placed as top sheet. All joints failed in the manner of polymer fracture in both tensile and shearing tests. For joints with different sheet material combinations, though the cross sections and geometrical parameters of joints had great difference, the static loads and absorbed energy values of joints were nearly the same. When AA5052 sheets were joined to HIPS sheets with different thickness values, with the increase of polymer sheet thickness, the flaring degree of rivet decreased, while static loads and absorbed energy values of joints increased. This was because the strength of interlock structure was higher than that of polymer sheet and the strength of joint was determined by the strength of polymer sheet.

Investigating the effect of jointed environment on the cracked concrete arch dam in 3D conditions using FEM

Concrete arch dams require foundation and abutment with high resistance since they have a particular structure and bear almost high loads induced by hydrostatic pressure. On the other hand, rock masses with high strength are fractured over time under tectonic effects and thermal stresses and usually, they include different degrees of joints. Previous investigations showed that, in most cases, these joints greatly affect the rock masses safety. For this reason, in the present study, the role of joints in the initial evaluation of rock mass as foundation and abutment was investigated for a cracked concrete arch dam. The effect of various geometrical parameters of joints, including their orientation and mechanical characteristics, on the safety of the foundation and abutment of cracked concrete arch dam was examined using finite element method (FEM). Different stages of dam construction were implemented in 3D modeling in order to apply real loads. To investigate the constructed models, the Morrow Point dam was selected as base dam and it was verified. The results showed that the geometric pattern of joints (slope and slope direction) and their mechanical characteristics significantly influence the safety of concrete dam supports. By controlling these parameters, the positioning conditions of dams can be evaluated. The effects of these parameters on the crack conditions are discussed in detail for a better understanding of further studies.

Bearing strength and failure behavior of pinned hybrid glass-flax composite laminates

The aim of the present work is to evaluate the influence of external layers of glass woven fabric on the pin-hole strength of flax/epoxy laminates. Single lap bearing tests were carried out to evaluate the fastened joint performances depending on laminate stacking sequence. In order to better identify the mechanical behavior of the hybrid laminate, full glass and flax laminates were also compared. In particular, bearing stress and failure mechanisms were investigated at varying joint geometry. Furthermore, an experimental failure map, clustering main failure modes of pinned hybrid composite laminate, was used to better clarify the relationship between mechanical failure and geometrical parameters of joints. The experimental results showed that the presence of external layers of glass fabric in a flax/epoxy laminate positively influences the mechanical performance of mechanically fastened joints. Furthermore, in a hybrid laminate, bearing fracture mechanism occurs for a large range of joint geometries, thus supporting the joining design of flax based composite laminates.