Design of Welded Joints: Weld Failure Modes, Welding Symbols: Type of Welds, Joints, Welding Position

2021 ◽  
pp. 327-342
Author(s):  
Dheerendra Kumar Dwivedi
Keyword(s):  
Welded Joints ◽  
Failure Modes ◽  
Weld Failure ◽  
Welding Position

STUDY ON FATIGUE BEHAVIOR OF STRENGTHENED NON-LOAD-CARRYING CRUCIFORM WELDED JOINTS USING CARBON FIBER SHEETS

2012 ◽  
Vol 12 (01) ◽  
pp. 179-194 ◽  
Author(s):  
TAO CHEN ◽  
QIAN-QIAN YU ◽  
XIANG-LIN GU ◽  
XIAO-LING ZHAO
Keyword(s):  
Stress Concentration ◽  
Carbon Fiber ◽  
Welded Joints ◽  
Failure Modes ◽  
Fatigue Behavior ◽  
Local Stress ◽  
Fatigue Loading ◽  
Cfrp Sheets ◽  
Load Carrying ◽  
Weld Toe

This paper reports an experimental study on the use of carbon fiber-reinforced polymer (CFRP) sheets to strengthen non-load-carrying cruciform welded joints subjected to fatigue loading. Failure modes and corresponding fatigue lives were recorded during tests. Scatter of test results was observed. Thereafter, a series of numerical analyses were performed to study the effects of weld toe radius, the number of CFRP layers and Young's modulus of reinforced materials on local stress concentration at a weld toe. It was found that fatigue life of such welded connections can be enhanced because of the reduction of stress concentration caused by CFRP strengthening. Parametric study indicates that the weld toe radius and the amount of CFRP are the key parameters influencing the stress concentration factors and stress ranges of the joint. Enhancement of modulus for adhesive and CFRP sheets can also be beneficial to the fatigue performance to some extent.

scholarly journals The dangers of single-lap shear testing in understanding polymer composite welded joints

2021 ◽  
Vol 379 (2203) ◽  
pp. 20200296 ◽  
Author(s):  
Irene Fernandez Villegas ◽  
Calvin Rans
Keyword(s):  
Polymer Composite ◽  
Welded Joints ◽  
Failure Modes ◽  
Local Heating ◽  
Welding Process ◽  
Joint Mechanics ◽  
Process Testing ◽  
Lap Shear ◽  
Design Values ◽  
Welding Processes

Single-lap shear (SLS) joints are straightforward to manufacture. This makes them especially attractive for testing polymer composite welded joints. Owing to local heating, which is characteristic of composite welding processes, the production of more geometrically intricate joints (such as double-lap or scarfed joints) or bigger joints (such as end-notched flexure or double cantilever beam) typically entails significant complexity in the design of the welding process. Testing of SLS joints is also uncomplicated and, even though, owing to mixed-mode loading and uneven stress distribution, it does not provide design values, it is widely acknowledged as a valuable tool for comparison. Even so, comparing different aspects of composite welded joints through their corresponding SLS strength values alone can be deceptive. This paper shows that comparison of different welding processes, adherend materials, process parameters or different types of joining techniques through SLS testing is only meaningful when strength values are combined with knowledge on other aspects of the joints such as joint mesostructure, failure modes and joint mechanics. This article is part of a discussion meeting issue ‘A cracking approach to inventing new tough materials: fracture stranger than friction’.

Analysis of Quality of Welded Joints of Iron-Concrete Products

2019 ◽  
Vol 942 ◽  
pp. 121-130 ◽  
Author(s):  
Ludmila Redko ◽  
Inna Plotnikova ◽  
Nataliya Chicherina ◽  
Olga Tchaikovskaja ◽  
Josefa Bastida
Keyword(s):  
Economic Development ◽  
Life Cycle ◽  
Statistical Methods ◽  
Welded Joints ◽  
Failure Modes ◽  
Welding Process ◽  
Negative Effects ◽  
High Quality ◽  
Welded Structures

The search for effective methods of management is one of the strategic directions of economic development. To obtain high-quality products, organizations should manage nonconformities and causes of product defects. The paper focuses on the analysis of groups of defects of welded joints using statistical methods. Welding process was considered as one of the processes of management. The possible causes of nonconformities were indicated. The method of failure modes and effects analysis was used to quantify the level of risk. A matrix of consequences and probabilities was presented, and critical risks and risk situations were selected. The proposed measures to eliminate or minimize negative effects enable identification of problem areas of the life cycle of welded structures.

Opening Contribution 5: Collaborative Approach to Weld Quality by Designer and Inspector

1966 ◽  
Vol 181 (11) ◽  
pp. 20-29
Author(s):  
C. Atkinson
Keyword(s):  
Welded Joints ◽  
Nuclear Power ◽  
Fatigue Cracking ◽  
Non Destructive Testing ◽  
Destructive Testing ◽  
Power Stations ◽  
Weld Failure ◽  
The Index System ◽  
The Cost ◽  
Non Destructive

Most engineering components are subject to inspection at some stage, particularly those incorporating welded joints. Often the task of the welder and inspector is hampered by the location of joints in positions difficult of access. This is just one aspect of poor design which could be eliminated by collaboration between designer and inspector at the outset. Up to the present, insufficient attention has been paid by designers to important features such as the weldability of materials, joint geometry, siting of welds, feasibility of heat treatment, and surface finish. The increasing use of non-destructive testing, particularly ultrasonics and radiography, has highlighted inspection problems, and as a result, designers are becoming more aware of their ultimate influence on inspection. Although the aims of the designer and inspector are the same—adequate service performance at lowest cost without danger of shutdown—the designer's interest appears to wane as the inspector's functions become more significant. A prolific cause of weld failure is fatigue cracking caused by stress-concentration at welded joints, yet how many designers realize that the external contour of a weld cannot approach the neat appearance indicated on drawings unless expensive grinding or machining is done? The paper will attempt to explore, with the aid of examples, the avenues where more co-operation is needed between designer and inspector. In addition the paper will present a new concept in the designer/inspector relationship in the form of a ‘failure index’ calculated from a number of variables known at the outset. This is a scheme to enable the designer to anticipate the relative amounts of inspection to be applied to various parts of complicated welded fabrications like those in conventional and nuclear power stations. The index system was devised specially as a collaborative link between designer and inspector in a field where the cost of failure in service can be enormous.

Study on Fracture Properties of High-Density Polyethylene (HDPE) Pipe

2004 ◽  
Vol 261-263 ◽  
pp. 153-158 ◽  
Author(s):  
Fang Juan Qi ◽  
Li Xing Huo ◽  
You Feng Zhang ◽  
Hong Yang Jing
Keyword(s):  
Welded Joints ◽  
High Density Polyethylene ◽  
Failure Modes ◽  
Welded Joint ◽  
High Density ◽  
Replica Method ◽  
Silicon Rubber ◽  
Hdpe Pipe ◽  
Fusion Welded Joints ◽  
Pipe Materials

Butt-fusion welding is the main technology to join high-density polyethylene (HDPE) plastic pipes, which are widely used in transport the water, gas and corrosive liquid. Investigation shows that one of the failure modes of HDPE pipe is the crack slowly grows across the thick direction and leads to failure at last, so that it is very important to study the resistance to crack initiation of HDPE pipe and its butt-fusion welded joint. In this study, the elastic-plastic fracture mechanics parameter, crack opening displacement (COD) is used to describe the fracture initiation behaviors for the HDPE materials and its butt-fusion welded joints. The resistance to initiation fracture of HDPE pipe materials and butt-fusion welded joints were investigated at different temperature by using multiple specimen resistance curve method and silicon-rubber replica method. The results show that saturation initial crack COD- δis of HDPE pipe materials and butt-fusion welded joints decreases with the decreasing temperature. The δis of butt-fusion welded joints is lower than that of HDPE pipe materials. Investigation also proved that the silicon-rubber replica method is more suitable for HDPE engineering material than the multiple specimen method. At the same time the statistic distribution of the δis of HDPE butt-fusion welded joint was conducted. The results show that the value of the δis has the statistic variance inherently. The optimum fitting distribution of COD is Weibull distribution with three parameters.

scholarly journals EFFECT OF WELDING POSITION ON THE MECHANICAL PERFORMANCE OF MANUAL METAL ARC WELDELD JOINTS VIA ANALYSIS OF VARIANCE

2020 ◽  
Vol 4 (6) ◽  
Author(s):  
Rui Rosa de Morais Júnior ◽  
Marcelo Xavier Guterres ◽  
Alexandre Ferreira Galio ◽  
Henara Lillian Costa
Keyword(s):  
Mechanical Properties ◽  
Analysis Of Variance ◽  
Welded Joints ◽  
Arc Welding ◽  
Mechanical Performance ◽  
Tensile Tests ◽  
Total Displacement ◽  
Metal Arc Welding ◽  
Plastic Displacement ◽  
Welding Position

Positional welding is a common challenge in many manufacturing practices and the welding position can affect the mechanical properties of welded joints during manual metal arc welding. This work uses tensile tests to investigate the mechanical properties of welded joints, aiming to test the hypothesis of the influence of welding position on tensile strength, total displacement before rupture and plastic displacement before rupture. This hypothesis was tested for three different coated electrodes (AWS E6010, AWS E6013 and AWS E7018) and three welding positions (1G, 3G and 4G), accounting for nine types of specimens. For each type of specimen, ten repetitions were carried out. Analysis of Variance (ANOVA) was used to test the hypotheses. The welded joints using the welding position 1G presented higher rupture load and larger total displacement before rupture than the other positions.

Weld Rod Fatigue Analysis Using Effective Notch Stress Method

2018 ◽  
Author(s):  
Kumarswamy Karpanan ◽  
Allison Weber Kirk ◽  
Gerald Hershman
Keyword(s):  
Fatigue Life ◽  
Welded Joints ◽  
Failure Modes ◽  
Welding Process ◽  
Fatigue Analysis ◽  
Fillet Welds ◽  
Notch Stress ◽  
Effective Notch Stress ◽  
Weld Fatigue ◽  
Weld Root

Welds are one of the commonly used joint types and are employed extensively in subsea oil and gas production equipment. Commonly used weld joints in subsea components are fillet, butt, full-penetration, plug, and girth. Fatigue is one of the critical failure modes for welded joints. Welded joints are complex to analyze for fatigue loading due to the microstructure change during the welding process. The welding process also induces residual stress in the heat affected zone (HAZ) surrounding the weld. This, in turn, can adversely affects the fatigue life of the joint. The S-N fatigue approach is commonly used for weld fatigue analysis due to the simplicity of this method. Industry standards such as DNV, IIW, BS-7608, and ASME BPVC Sec VIII Div. -2 or -3 are typical references for this type of analysis. For subsea specific applications, DNV-RP-C203 and BS-7608 are generally used because these two standards provide S-N curves for welds in “air” as well as in “seawater with cathodic protection”. These two codes also provide S-N curves for various weld geometries ranging from simple fillet welds to complex tubular joints. Some of the weld fatigue analysis techniques used in the subsea industry are the: nominal stress approach, structural hot spot stress approach, effective notch stress approach (ENS), structural stress method (ASME VIII-2, -3) and the Fracture mechanics based fatigue crack propagation (FCG) approach. This paper presents the fatigue analysis of fillet welds in bore inserts using the ENS method. In the ENS method, a 1mm radius notch is modelled at the weld root or toe, see Figure 1, which yields a finite weld root stress. The stress analysis is carried out using FEA and the stresses on the notch along with the appropriate fatigue curve are used to estimate the weld root fatigue life.

On Utilization of Material Failure Criterion in Modeling Pull-Out Failure of Spot-Welded Joints

2013 ◽  
Author(s):  
Long Zeng ◽  
Yong Xia ◽  
He Zhao ◽  
Qing Zhou
Keyword(s):  
Test Data ◽  
Failure Criterion ◽  
Welded Joints ◽  
Failure Modes ◽  
Failure Criteria ◽  
Spot Weld ◽  
Test Results ◽  
Pull Out ◽  
Metal Sheets ◽  
Spot Welded

Two distinct failure modes of spot welds, interfacial and pull-out failure, are observed in impact of spot-welded structures. Automotive industries prefer pull-out as the predominant failure mode since it makes more use of load-bearing capacity of a joint. For the time being, finite element models for predicting pull-out failure of spot weld have not been well developed. The dependence of failure on the stress state, i.e., a locus in the space of failure strain and stress triaxiality, needs to be known for base metal sheets when modeling spot weld pull-out. Existing failure criteria, with or without physical base, were formulated to provide an effective way to utilize a limited number of tests to reconstruct the failure locus. This paper is aimed to evaluate influence of failure criterion form for identifying failure parameters on modeling spot weld pull-out. As for material tests, various specimen configurations of metal sheets were designed to obtain stress states around a number of typical stress triaxialities. These test results constructed a set of test data for calibrating failure criterion. The spot-welded joints were also tested two different coupon configurations. The force-displacement curves were obtained, and the deformation fields around the spot weld nugget were achieved with DIC. These test results of joints were utilized to validate the model of spot weld pull-out. Two prevailing failure criteria, shear-modified Gurson model and Modified Mohr-Coulomb model, were selected to predict the complicated spot weld pull-out failure. Parameters in each of the two failure criteria were identified with material test data. Various simulation results were thereafter obtained based on different failure criteria. The two criteria were evaluated in terms of their predictive capabilities for spot weld pull-out failure.

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