Fracture and fatigue of welded joints and structures pdf

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fracture and fatigue of welded joints and structures pdf

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Stress Analysis and Fatigue of welded structures

Chapter 6: Improving weld class systems in assessing the fatigue life of different welded joint designs. Chapter 9: Reliability aspects in fatigue design of welded structures using selected local approaches: the example of K-nodes for offshore constructions. The failure of any welded joint is at best inconvenient and at worst can lead to catastrophic accidents. Fracture and fatigue of welded joints and structures analyses the processes and causes of fracture and fatigue, focusing on how the failure of welded joints and structures can be predicted and minimised in the design process. Part one concentrates on analysing fracture of welded joints and structures, with chapters on constraint-based fracture mechanics for predicting joint failure, fracture assessment methods and the use of fracture mechanics in the fatigue analysis of welded joints. In part two, the emphasis shifts to fatigue, and chapters focus on a variety of aspects of fatigue analysis including assessment of local stresses in welded joints, fatigue design rules for welded structures, k-nodes for offshore structures and modelling residual stresses in predicting the service life of structures. With its distinguished editor and international team of contributors, Fracture and fatigue of welded joints and structures is an essential reference for mechanical, structural and welding engineers, as well as those in the academic sector with a research interest in the field.

This article addresses the study of crack behavior elicited on axial fatigue in specimens joined by butt weld made of steel ASTM A36 by using fracture mechanics and simulation software of finite elements Ansys APDL, Franc3D. The computational model was initially to define the geometry model by using CAD software. Specimens with Weld Reinforcement of 2 mm and 3mm were simulated. Subsequently, the type of element for the mesh, the information inclusion concerning material mechanical properties and load conditions were selected. By using Franc3D software, the crack propagation phenomenon is analyzed, and its growth parameters have been established. In this way, it is possible to calculate the magnitude of stress intensity factor SIF along the crack front. It is concluded that the stress located in the weld toe is maximized proportionately to the size of the weld reinforcement due to the concentration effect of geometric stress.

Fracture and Fatigue Analysis of Welded Structures Using Finite Element Analysis

Fatigue of welded joints can occur when poorly made or highly stressed welded joints are subjected to cyclic loading. During welding, joints are formed between two or more separate pieces of material which can introduce defects or residual stresses. Under cyclic loading these defects can grow a fatigue crack, causing the assembly to fail even if these cyclic stresses are low and smaller than the base material and weld filler material yield stress. Welded sample specimens undergo repeated loading at a specified stress amplitude, or fatigue strength, until the material fails. With the data collected, fatigue strength can be plotted against the corresponding number of cycles for a specific material, welded joint and loading. During the welding process, residual stresses can present themselves in the area of the weld, either in the heat affected zone or fusion zone.

Fatigue of welded joints

The stress state evaluation process of two standards is studied, and the stress state evaluation method of two standards is programmed by computer language. Among them, ASME standard can evaluate the stress state of welding structures without defects and with defects. In order to verify the feasibility of the method, under the fatigue load of en standard, the method is applied to the welding structure design of the rail car frame. The results show that the evaluation based on IIW standard is stricter, and the stress factor of the weld between the crossbeam and the traction pull rod seat is the largest, the value is 0. With the increase of the number of defects, the stress level of the welded joint increases and the fatigue life decreases.

Fatigue behaviour of welded joints in offshore steel structures Navigation Menu. Navigation Menu. Publications Office of the EU.

Fracture and Fatigue of Welded Joints and Structures

Research on stress state level evaluation method of complex steel welded structures

Fatigue analyses of weldments require detailed knowledge of the stress fields in critical regions. The stress information is subsequently used for finding high local stresses where fatigue cracks may initiate and for calculating stress intensity factors and fatigue crack growth. The method proposed enables the determination of the stress concentration and the stress distribution in the weld toe region using a special shell finite element modelling technique. The procedure consists of a set of rules concerning the development of the finite element mesh necessary to capture the bending and membrane structural stresses. The structural stress data obtained from the shell finite element analysis and relevant stress concentration factors are subsequently used to determine the peak stress and the non-linear through-thickness stress distributions. The peak stress at the weld toe is subsequently used for the determination of fatigue crack initiation life.

Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. DOI: Current thesis work focuses on an automated fracture and fatigue analysis of welded components.

E-mail: ronaldo. This work presents a new computational approach to estimate the fatigue life in welded joints, taking into account three-dimensional, non-proportional, and out-of-phase stresses; the thermomechanical properties of steel; parameters of the welding process; and the effects of residual stresses. We use the mechanical equations of continuous and cumulative fatigue damage found from Multiaxial RainFlow, the Wang and Brown and critical plane methods, and the Findley criteria approach. The numerical finite element method, available with software, is used to simulate the formation of residual stress and quantify its influence by solving equations. Based on the analysis of numerical results, we were able to prevision the crack location and angles of propagation of a high cycle fatigue crack with totally random loads in a metallic structure. We conclude that the result of the computational method is valid and can be used to estimate and life in fatigue in welded joints. In many structural applications of steel or composite steel-concrete QIAN et al.

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