Search results for "Mechanical joint"
showing 10 items of 15 documents
Failure maps to assess bearing performances of glass composite laminates
2018
Aim of this article is the assessment of the bearing mechanical performances of pin-loaded glass laminates as function of their geometrical configuration. To this concern, 32 specimens having different hole diameter (D), laminate width (W), and hole center to laminate free edge distance (E) have been tested under bearing conditions. The maximum bearing stress and the stress-displacement curves were analyzed as function both of hole to laminate free edge distance E and hole diameter D. Moreover, an experimental 2D failure map was created by placing the experimental results (i.e., the kind of failure mechanism occurred for each geometrical configuration) in the plane E/D versus W/D ratios. In…
Influence of Joint Geometry on Micro and Macro Mechanical Properties of Friction Stir Spot Welded Joints
2014
AbstractSpot welding can be considered a very common joining technique in automotive and transportation industries as it permits to obtain effective lap-joints with short process times and what is more it is easily developed through robots and automated systems. Recently, Friction Stir Spot Welding (FSSW) has been proposed as a natural evolution of the already known Friction Stir Welding (FSW) process, allowing to obtain sound spot joints that do not suffer from the insurgence of typical welding defects due to the melting of the base material. Similarly to FSW, both geometrical and technological parameters must be considered as they affect the material flow and the heat flux generated durin…
Analysis of the mechanical performance of hybrid (SPR/bonded) single-lap joints between CFRP panels and aluminum blanks
2013
Abstract The increasing use of innovative materials in manufacturing of modern mechanical components has led to the development of reliable joints between innovative (composite materials etc.) and traditional materials (steel, aluminum etc.). In the last few years, hybrid joints, combining the advantages of the adhesive joints and traditional mechanical joints as bolted or riveted joints, have been shown an increasing industrial interest especially in automotive and aerospace sectors. In the present paper a systematic experimental study of hybrid lap joints was carried out with the aim to detect the optimal joint configuration. Tensile tests on hybrid joints made by combining adhesive bondi…
Tool-Point Control for a Redundant Heave Compensated Hydraulic Manipulator
2012
Abstract In this paper, theoretical and experimental implementation of heave compensation on a redundant hydraulically actuated manipulator with 3-dof has been carried out. The redundancy is solved using the pseudo-inverse Jacobian method. Techniques for minimizing velocities and avoiding mechanical joint saturations is implemented in the null space joint motion. Model based feed-forward, combined with a PI-controller handles the velocity control of each joint. A time domain simulation model has been developed, experimentally verified, and used for controller parameter tuning. Model verification and experimental results are obtained while the manipulator is exposed to wave disturbances crea…
An analysis of through-thickness residual stresses in aluminium FSW butt joints
2006
Abstract In the paper, the results of a wide experimental campaign on friction stir welding (FSW) of aluminum alloys are reported. The attention was focused on the through-thickness residual stresses that occur on aluminum joints, after the welding process. In detail, using the hole-drilling method the residual stresses distribution in the zone close to the tool shoulder border of the joint advancing side, has been investigated; four different aluminum alloys and three different process conditions have been considered. The experimental analysis has shown that unlike traditional welding processes, the residual stresses are negative in the surface of the examined zone, and increase with depth…
Experimental design of the bearing performances of flax fiber reinforced epoxy composites by a failure map
2018
Abstract This paper represents the first effort aimed to the investigation of the pin/hole contact stress and failure mechanisms of epoxy composites reinforced with woven flax fabrics, underwent to tensile bearing tests. In particular, the maximum loads and failure modes are evaluated at varying the laminate geometrical configuration. In order to optimize the use of polymer composites reinforced with flax fibers in structural applications, an experimental failure map, identifying main failure modes of mechanically fastened joints, is obtained as function of hole diameter, distance of the hole from the free edge of the laminate and laminate width. Moreover, a theoretical approach based on th…
Bearing strength and failure behavior of pinned hybrid glass-flax composite laminates
2018
Abstract 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 geometr…
Evolution of the bearing failure map of pinned flax composite laminates aged in marine environment
2020
Abstract Aim of the present paper is to evaluate how the bearing behavior of pinned flax composites can be influenced by their exposition to critical environment such as marine one. To this scope, flax fibers/epoxy pinned laminate was exposed up to 60 days to salt-fog environment, according to ASTM B 117 standard. In particular, samples having different hole diameter (D), laminate width (W), and hole center to laminate free edge distance (E) have been tested under single lap bearing tests at varying the aging exposition time. Following this procedure, an experimental 2D failure map clustering main failure modes was created by placing the experimental results in the plane E/D versus W/D rati…
Failure Map of Composite Laminate Mechanical Joint
2007
The aim of this research is to investigate the pin/hole contact stress of a composite laminate and failure modes when submitted to tensile bearing tests. The limit loads and failure modes are evaluated as a function of pin diameter and hole position. Analyzing the joint geometry effect on the fracture mechanisms, a failure map is obtained, identifying three regions of typical failure modes of mechanically fastened joints. A theoretical approach is proposed to identify the field of each fracture mode to obtain a simple experimental methodology to support the design of a particular joint laminate. In addition, a simplified numerical model is proposed to evaluate near the hole the stress/stra…
Fatigue strength of a single lap joint SPR-bonded
2011
In the last years, hybrid joints, meaning with this the joints which consist in combining a traditional mechanical joint to a layer of adhesive, are gradually attracting the attention of various sectors of the construction of vehicles and transportation industries, for their better performance compared to just mechanical joints (self-piercing riveting SPR, riveting, and so on) or just to bonded joints. The paper investigates the fatigue behavior of a single lap joint self-piercing riveted (SPR) and bonded throughout fatigue tests. The considered geometric configuration allowed the use of two rivets placed longitudinally; an epoxy resin was used as adhesive. In the first part of the work sta…