ESDU 76007-1976 轴向载荷下钢制纵向角焊附件与接头的疲劳强度

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76007



FATIGUE STRENGTH OF LONGITUDINAL FILLET WELDED ATTACHMENTS AND

JOINTS IN STEELS UNDER AXIAL LOADING

1. NOTATION

Both SI and British units are quoted.

2. NOTES

This Item presents data on the fatigue strength of longitudinal fillet welded attachments and joints between

steel members of the types shown in Sketch 2.1 to 2.4 tested in the as-welded condition. The data are

obtained from specimens welded in the laboratory. The range of sizes of the test specimens is quoted on

the relevant figure.

Provided that the welds are sound and free from major defects, the fatigue strength of longitudinal fillet

welds in the untreated and unmachined condition is independent of the properties of the plate and weld

materials (except in the low cycle fatigue region, that is, when is greater than about 85 per cent of the

material tensile strength, at which the endurance is about cycles). The fatigue strength is also

independent of the applied mean stress. This is because as-welded longitudinal joints contain a system of

highly localised residual stresses in the direction of loading which result from the internal constraints applied

during cooling of the weld, and which are of the order of the material yield strength. Hence, any applied

loading will cause local yielding in the region of the end of the weld run during the first few load cycles.

The actual stress experienced in the critical region will thereafter cycle between the yield strength and the

yield strength less the applied stress range, irrespective of applied mean stress, except in cases of high

compressive mean stress.

throat depth (see Sketch 2.5)min

distance of weld end from end of loaded plates m in

modulus of elasticity of plate material N/m2lbf/in2

length of weld run of loaded plate m in

endurance

load applied to joint N lbf

nominal alternating stress (half range) in loaded plate N/m2lbf/in2

weld leg length (see Sketch 2.5)min

thickness of loaded plate m in

width of loaded plate m in

2Sa

410

Issued April 1976

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76007



Sketch 2.1 Non-load-carrying joint

(stiffener type) Sketch 2.2 Non-load-carrying joint

(flange type)

Sketch 2.3 Load-carrying joint

(double strap type)

Sketch 2.4 Load-carrying joint

(egg-box type)

Sketch 2.5 Illustrating the assumed throat

depth of a fillet weld and showing

a type C failure

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76007



Provided the weld run is continuous and without severe ripples or defects, all fatigue failures start at one

or both ends of the weld run. Two modes of failure can be distinguished. The fatigue crack may be initiated

at a small defect in the transition region between the plate and the weld bead, and subsequently propagate

transversely through the plate. Alternatively, a crack in the weld throat may begin at the end of the weld in

the weld bead and propagate to cause failure along the weld bead or turn to run transversely through the

loaded plates. The mode of failure is influenced by the throat area of the weld bead relative to the plate

sizes and by the length of the weld run.

Data for non-load-carrying stiffener type attachments are given in Figure 1. These data are for a wide range

of steels and a wide range of applied stress conditions. Figure 2 shows data for non-load-carrying joints of

the flange type and compares these with the data of Figure 1. Figure 3 shows data for asymmetric joints of

the non-load-carrying stiffener type, for example stiffeners welded on one side of the plate only. Data for

load-carrying joints of these types are given in Figures 4 and 5.

3. NON-LOAD-CARRYING JOINTS

3.1 Stiffener-type Attachments

The data for this type of joint, shown in Sketch 2.1, are given in Figure 1. The data show no positive knee

and can be represented by a straight line when plotted on a log/log basis. The mean line of Figure 1 can be

expressed by the equation * over a wide range of tensile mean stress. All

failures begin in the plate at the ends of the weld run, see Sketch 2.1, and fatigue cracks propagate through

and across the loaded plate perpendicular to the stressing direction. Joints with attachments that have been

welded all round, that is, with transverse end welds, have fatigue strengths that are well within the scatter

of the data but are lower on average than those with only longitudinal welds. The reduced fatigue strength

may be due to an increased stress concentration at the ends of the weld runs.

The distribution of the data about the mean is sensibly Gaussian and statistical analysis has led to the

confidence limits shown on the figure. The inner limits give bounds within which there is 95 per cent

confidence that 95 per cent of the population will occur and the outer limits give bounds within which there

is 99 per cent confidence that 99 per cent of the population will occur.

3.2 Flange-type Attachments

This type of joint is shown in Sketch 2.2. The data, given on Figure 2, indicate that the fatigue strength falls

slightly below that of stiffener-type specimens although remaining within the 99 per cent confidence limits

of Figure 1. The lower fatigue strength is thought to be due to the proximity of the weld ends to the edges

of the loaded plate. The location of failure is through the loaded plate from the weld ends as indicated in

Sketch 2.2.

The dashed line in Figure 2 is the mean line for the data.

3.3 Non-load-carrying Asymmetric Joints

The fatigue strength of asymmetric joints is not necessarily lower than that of symmetric joints and may

even be higher as shown in Figure 3, where the dashed line is a mean line through data relating to

stiffener-type joints with attachments on one side of the plate only. This strengthening effect may not exist

for long stiffeners as it may be due to compression at the ends of the stiffener caused by secondary bending.

*The value of E is taken as 207 000 MN/m2 .

N3.65 10 4–

×E/2Sa

()

2.9

30 106 lbf/in2

×()

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标签： #接头 #钢 #载荷

摘要：

本文档详细介绍了ESDU 76007-1976标准，该标准专门针对轴向载荷作用下钢制纵向角焊附件与接头的疲劳强度进行评估与设计。内容涵盖焊接接头的疲劳破坏机理、影响疲劳寿命的关键因素（如焊接几何形状、应力集中、载荷频率与幅值等），以及基于大量实验数据与工程实践总结出的疲劳强度预测方法。该标准适用于钢结构设计、船舶、桥梁、压力容器及重型机械等领域中纵向角焊缝的疲劳分析，为工程师提供了可靠的参考依据，以提升焊接结构在循环载荷下的安全性与耐久性。通过遵循该标准，设计人员能够更准确地评估焊缝疲劳寿命，避

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ESDU 76007-1976 轴向载荷下钢制纵向角焊附件与接头的疲劳强度

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