No undercut at frontal welds! Grinding parallel to stress direction. Reinforcements welded on with fillet welds, toe ground Toe as welded Analysis based on modified nominal stress. Tubular branch or pipe penetrating a plate, K-butt welds. Requirements and Remarks Impairment of inspection of root cracks by NDT may be compensated by adequate safety considerations see chapter 5 or by downgrading down to 2 FAT classes.

Nozzle welded on plate, root pass removed by drilling. Nozzle welded on pipe, root pass as welded. Requirements and Remarks Root of weld has to penetrate into the massive bar in order to avoid a gap perpenticular to the stress direction. Circular hollow section welded to component with single side butt weld, backing provided. Root crack. Root of weld has to penetrate into the backing area in order to avoid a gap perpenticular to the stress direction.

Circular hollow section welded to component single sided butt weld or double fillet welds. Impairment of inspection of root cracks by NDT may be compensated by adequate safety considerations see chapter 5 or by downgrading down to 2 FAT classes. Circular hollow section with welded on disk K-butt weld, toe ground Fillet weld, toe ground Fillet welds, as welded. The resistance values refer to the as-welded condition unless stated otherwise. The effects of welding residual stress are included. Effects of misalignement are not included. See detail 7 in table 8. Note: Table does not cover effects of misalignment.

They have to be considered explicitely in determination of stress. The reference detail should be chosen as similar as possible to the detail to be assessed. Thus the procedure will be: a b c d e f Select a reference detail with known fatigue resistance, which is as similar as possible to the detail being assessed with respect to geometric and loading parameters.

Identify the type of stress in which the fatigue resistance is expressed. This is usually nominal stress as in tables in chapter 3. Establish a FEM model of the reference detail and the detail to be assessed with the same type of meshing and elements following the recommendations given in 2. Load the reference detail and the detail to be assessed with the stress identified in b. Determine the structural hot spot stress Fhs, ref of the reference detail and the Structural hot spot stress Fhs, assess of the detail to be assessed.

The fatigue resistance for 2 million cyles of the detail to be assessed FATassess is then calculated from fatigue class of the reference detail FATref by:. The definition of the FAT class is given in chapter 3. The fatigue resistance value refers to the as-welded condition. The effect of welding residual stresses is included. Possible misalignment is not included. The fatigue enhancement factor depends on the level and direction of residual stresses.

It should only be used if reliable information or estimation of the residual stress level was present. No constraints in assembly. Small scale thin-walled simple structural elements containing short welds. Parts or components containing thermally cut edges. Complex two- or three-dimensional welded components, components with global residual stresses, thickwalled components. Normal case for welded components and structures. It has to be noted in this respect that stress relief in welded joints is unlikely to be fully effective, and long range residual stresses may be introduced during assembly of prefabricated welded components.

The reduced strength is taken in consideration by multiplying the fatigue class of the structural detail by the thickness reduction factor f t. Cruciform joints, transverse T-joints, plates with transverse attachments Cruciform joints, transverse T-joints, plates with transverse attachments Transverse butt welds Butt welds ground flush, base material, longitudinal welds or attachements.

The plate thickness correction factor is not required in the case of assessment based on effective notch stress procedure or fracture mechanics. These techniques improve the weld profile, the residual stress conditions or the environmental conditions of the welded joint. The improvements methods are: a Methods of improvement of weld profile: Machining or grinding of weld seam flush to surface Machining or grinding of the weld transition at the toe Remelting of the weld toe by TIG-, plasma or laser dressing b Methods for improvement of residual stress conditions: Peening hammer-, needle-, shot- or brush-peening Coining Overstressing page The effects of all improvement techniques are sensitive to the method of application and the applied loading, being most effective in the low stress high cycle regime.

They may also depend on the material, structural detail and dimensions of the welded joint. Consequently, fatigue tests for the verification of the procedure in the endurance range of interest are recommended chapters 3. For some post welding improvement procedures, direct recommendations are given below. They may be used in connection with repair or upgrading of existing structures, not for general use in design in order to obtain a longer fatigue life than the use of standard design S-N curves would give.

The recommendations apply to nominal stress and structural hot spot stress method, they do not apply to effective notch stress and fracture mechanics method. They are limited to structural steels up to a specified yield strength of MPa and to structural aluminium alloys commonly used in welded structures, primarily of the AA and AA series. The recommendations apply to welded joints of plates, of sections built up of plates or similar rolled or extruded shapes, and hollow sections. If not specified else, the plate thickness range for steel is from 6 to mm, for aluminium from 4 to 50 mm.

The application is limited to joints operating at temperatures below the creep range. In general, the recommendations do not apply at low cycle fatigue conditions, so the nominal stress range is limited to. For the special improvement procedures additional restrictions may be given.

## Fatigue Design of Welded Joints and Components

Fig: 3. All other points of a possible start of fatigue cracks therefore should be carefully considered as e. The recomendations do not apply to joints operating under free corrosion. The grinding has firstly to remove these defects and secondly to create a smooth weld transition and thus to reduce the stress concentration. All embedded imperfection which emerge to the surface at grinding must be repaired. For the details of application see ref. The benefit of burr grinding is given as a factor on the stress range of the fatigue class of a non-improved joint. All S-N curves and fatigue classes for 1.

Butt joints to be assessed by the nominal stress fatigue class.

By TIG tungsten inert gas dressing, the weld toe is remolten in order to remove the weld toe undercut or other irregularities and to smoothen the stress concentration of the weld transition. The details of the procedure are described in ref. By hammer peening, the material is plastically deformed at the weld toe in order to introduce beneficial compressive residual stresses.

The recommendation is restricted to steels with a specified yield strength up to MPa and structural aluminium alloys, both operating non-corrosive environment or under conditions of corrosion potection. The recommendations apply for plate thicknesses from 10 to 50 mm at steel and 5 to 25 mm at aluminium? For structural hot spot stress see recommendations for needle peening. By needle peening, the material is plastically deformed at the weld toe in order to introduce beneficial compressive residual stresses.

Before any application, it is recommended to grind the weld toe in order to remove undercut and weld toe irregularities and subsequently to finish with a sandpaper tool for a glossy surface. The details of the procedure are described in [xx]. At all peening techniques, the structural hot spot stress approach should be applied only to joints with fillet welds with any penetration and not to butt joints.

The structural hot spot stress, which includes the stress increase due to the structural geometry and possible page In this way, the base metal at the weld toe is assumed to have a lower fatigue strength than the peened weld. The fatigue reduction factor is a conservative approach and might be raised according to test evidence or application codes. This value is a conservative approach. It may be raised according to test evidence or an applicable code. Normal protection against atmospheric corrosion is assumed.

A corrosive environment or unprotected exposure to atmospheric conditions may reduce the fatigue class. The fatigue limit may also be reduced considerably. The effect depends on the spectrum of fatigue actions and on the time of exposure. No specific recommendations are given for corrosion fatigue assessment. In the absence of specified or measured material parameters, the values given below are recommended. They are characteristic values. Statistical methods offer tree ways of testing a limited number of samples from a larger population: It is recommended that test results are obtained at constant stress ratios R.

The S-N data should be presented in a graph showing log endurance in cycles as the abscissa and log range of fatigue actions as the ordinate. For crack propagation data, the log stress intensity factor range should be the abscissa and the log crack propagation rate per cycle the ordinate.

### Description:

For statistical evaluation, a Gaussian log-normal distribution should be assumed. The number of failed test specimens should be equal or greater than For other conditions, special statistical considerations are required. Many methods of statistical evaluation are available. Then, characteristic values are established by adopting curves lying k standard deviations 2 Stdv at a Fig. In the case of S-N data, this would be below the mean, while the curve above the mean would be appropriate in case of crack propagation data. Thus, more precisely, test results should analysed to produce characteristic values subscript k.

More details on the use of the confidence level and formulae are given in appendic 6. Different methos for testing exist. For the derivation of S-N curves, testing at two levels of the stress range F within the range of to cycles is preferred. For fracture mechanics crack propagation parameters, the range of stress intensity factor K should be distributed between threshold and brittle fracture levels.

Calculate exponents m and constant logC or logC0 resp. In case of S-N data, proper account should be taken of the fact that residual stresses are usually low in small-scale specimens. The results should be corrected to allow for the greater effects of residual stresses in real components and structures. This may be achieved either by testing at high R-ratios, e.

These heterogeneous populations of data require a special consideration in order to avoid an excessive and unnecessary calculative scatter.. The evaluation procedure should consist of the following steps: 1. Calculate the constant C of the SN Whler curve for each data point eq. Plot all values C into a Gaussian probability chart, showing the values of C on th abscissa and the cumulative survival probability on the ordinate.

Check the probability plot for heterogeneity of the population. If it is heterogeneous, separate the portion of the population which is of interest. Evaluate the interesting portion of population according to chapter 3. Other imperfections, not yet covered, may be assessed by assuming similar imperfections with comparable notch effect. Imperfect shape All types of misalignment including centre-line mismatch linear misalignment and angular misalignment angular distortions, roofing, peaking.

Undercut Volumetric discontinuities Gas pores and cavities of any shape. Solid inclusions, such as isolated slag, slag lines, flux, oxides and metallic inclusions. Planar discontinuities All types of cracks or cracklike imperfections, such as lack of fusion or lack of penetration Note that for certain structural details intentional lack of penetration is already covered, e.

This is the effect of all types of misalignment due to secondary bending. The additional effective stress concentration factor can be calculated by appropriate formulae. The fatigue resistance of the structural detail under consideration is to be lowered by division by this factor. Local notch effect Here, interaction with other notches present in the welded joint is decisive.

Two cases are to be distinguished: Additive notch effect If the location of the notch due to the the weld imperfection coincides with a structural discontinuity associated with the geometry of the weld shape e. This may be the case at weld shape imperfections. Competitive notch effect If the location of the notch due to the weld imperfection does not coincide with a structural geometry associated with the shape geometry of the weld, the notches are in competition.

## Fatigue Design Of Welded Joints And Components Recommendations Of Iiw Joint Working Group Xiii Xv

Both notches are assessed separately. The notch giving the lowest fatigue resistance is governing. Cracklike imperfections Planar discontinuities, such as cracks or cracklike imperfections, which require only a short period for crack initiation, are assessed using fracture mechanics on the basis that their fatigue lives consist entirely of crack propagation. After inspection and detection of a weld imperfection, the first step of the assessment procedure is to determine the type and the effect of the imperfection as given here.

If a weld imperfection cannot be clearly associated to a type or an effect of imperfections listed here, it is recommended that it is assumed to be cracklike. The resulting stress is calculated by stress analysis or by using the formulae for the stress magnification factor km given in appendix 6. Secondary shell bending stresses do not occur in continuous welds longitudinally loaded or in joints loaded in pure bending, and so misalignment will not reduce the fatigue resistance. However, misalignment in components, e.

Such cases should be assessed. Some allowance for misalignment is already included in the tables of classified structural details 3. In these cases the effective stress magnification factor km,eff should be calculated as given below. For the simultaneous occurrence of linear and angular misalignment, both stress magnification factors should be applied simultaneously using the formula: As misalignment reduces the fatigue resistance, the fatigue resistance of the classified structural detail 3.

Though undercut is an additive notch, it is already considered to a limited extent in the tables of fatigue resistance of classified structural details 3. Undercut does not reduce fatigue resistance of welds which are only longitudinally loaded. Before assessing the imperfections with respect to fatigue, it should be verified that the conditions apply for competitive notches, i. It is important to ensure that there is no interaction between multiple weld imperfections, be it from the same or different type.

Combined porosity or inclusions shall be treated as a single large one. The defect interaction criteria given in 3. Worm holes shall be assessed as slag inclusions. If there is any doubt about the coalescence of porosity or inclusions in the wall thickness direction or about the distance from the surface, the imperfections shall be assessed as cracks.

It has to be verified by NDT that the porosity or inclusions are embedded and volumetric. If there is any doubt, they are to be treated as cracks. The parameter for assessing porosity is the maximum percentage of projected area of porosity in the radiograph; for inclusions, it is the maximum length. Directly adjacent inclusions are regarded as a single one. Tungsten inclusions have no effect on fatigue behaviour and therefore do not need to be assessed. NDT indications are idealized as elliptical cracks for which the stress intensity factor is calculated according to 2.

The crack parameter a crack depth is the half-axis of the ellipse in the direction of the crack growth to be assessed. The remaining perpendicular half-axis is the half length of the crack c. The wall thickness parameter t is the distance from the center of the ellipse to the nearest surface. Surface cracks are described in terms of a circumscribing halfellipse. The wall thickness parameter is wall thickness t.

For details of dimensions of cracks and recategorization see appendix 6. For cracks near the plate edge, the distance b from the center of crack ellipsis to the plate edge was constantly assumed equalling c. This ensures conservative results. The tables have been calculated using the correction functions and the weld joint local geometry correction given in 6. In assessing a defect by the simplified procedure, the stress range Fi for the initial crack size parameter ai and the stress range Fc for the critical crack size parameter ac are taken.

The stress range F or the FAT class belonging to a crack propagation from ai to ac at 2A cycles is then calculated by:. For aluminium, the tables may be used by dividing the resistance stress ranges at 2A cycles FAT classes for steel by 3. Surface cracks at fillet weld toes ai It must be ensured that all three elements actions, resistance and assessment procedure correspond. Three procedures may be distinguished: a Procedures based on S-N curves, such as nominal stress approach Structural hot spot stress approach effective notch stress approach b c Procedures based on crack propagation considerations Direct experimental approach by fatigue testing of components or entire structures.

If the normal and shear stress vary simultaneously in phase, or if the plane of maximum principal stress is not changed significantly, the maximum principal stress range may be used. If normal and shear stress vary independently out of phase, in damage calculation the damage sums shall be calculated separately and finally added. Fracture mechanics crack propagation calculations should be based on maximum principal stress range.

The design resistance S-N curve may be modified further according to the needs of the damage calculation procedure. For constant amplitude loading, the characteristic stress range FR,k at the required number of stress cycles is firstly determined. Secondly the fatigue criterion is checked:. At variable amplitude loading, cumulative damage calculation procedure is applied.

Usually a modified "Palmgren-Miner"-rule, as described in 4. For load spectra which are sensitive to the position of the fatigue limit or cut-off limit, or in which the spectrum changes during the service time, additional assessment using the nonlinear damage calculation method described in 4. In fields of application, where no test data nor service experience exist and the shape of the stress spectrum is not close to constant amplitude, it is recommended to proceed according to the calculation given in in 4.

If the constant amplitude fatigue limit of the resistance S-N curve corresponds to an endurance less than cycles, the fatigue resistance curve has to be modified according. For fatigue verification it has to be shown that the calculated usable cycles are larger than the anticipated number of cycles occurring in service of the structure:. Although it is accepted that the stresses below the constant amplitude fatigue limit must be included in cumulative damage calculation relating to welded joints, there are currently different opinions how this should be achieved.

The method presented here fig. However, recent research indicates that it can be unconservative. Other suggestions recommend that the S-N curve should be extrapolated further down before the slope change is introduced. For critical cases or areas of doubt, the user should consult relevant published literature. The order of sequence of the blocks has no effect on the results of this calculation. In some cases it might be convenient to calculate an equivalent constant amplitude stress range FE and to compare it directly to the constant amplitude resistance S-N curve neglecting the constant amplitude fatigue limit.

Stepping down one class corresponds to a division by 1. So different levels of safety M of S-N curve can be achieved see 6. Where the parameters for a fracture mechanics fatigue assessment are not known and only the resistance S-N curve is known, the S-N curve can be used to derive dimensionless fracture mechanics parameters, which allow a damage calculation [31]. The procedure is based on the "Paris" power law of crack propagation. The characteristic stress intensity factor range KS,k of the fatigue action is calculated with the stresses of the spectrum Fi,S,k and the crack parameter a.

The fatigue verification is executed according to 4. The restrictions on life cycles given in 4. The actual fatigue class of a pre-damaged component is FATact. At stress intensity factors which are high compared with the fracture toughness of the material, Kc, an acceleration of crack propagation will occur. In these cases, the following extension of the "Paris" power law of crack propagation is recommended.

In the absence of an accurate value of the fracture toughness, a conservative estimate should be made. The number of life cycles N is determined by integration starting from an initial crack parameter ai to a final one af. The calculated number of life cycles N has to be greater or equal to the required number of cycles. In general, the integration has to be carried out numerically. The increment for one cycle is page It is recommended that a continous spectrum is subdivided to an adequate number of stress range blocks, e.

The entire size of the spectrum in terms of cycles should be adjusted by multiplying the block cycles by an appropriate factor in order to ensure at least 20 loops over the whole spectrum in the integration procedure. Verification of a component or structure for a specified survival probability under a special fatigue action stress history. Predimensioning may be done by the use of higher fatigue resistance data, accoding to a lower survival probability in comparison with the. Then the verification is achieved by a subsequent component testing.

A predimesioning leading to the mean values of the the resistance data may be done by multiplying the resistance values in termes of stress by a factor of 1. The verification or assessment depends of the safety strategy considered see 5. Safe life, fail safe and damage tolerant strategy have to be distinguished.

## Recommendations for Fatigue Design of Welded Joints and Components

The fatigue tests should be performed using the data of the fatigue action history see 3. The all failed approach is the normal way of testing at small size samples of which each specimen represents the same weld details. The statistical analysis uses the data of the failed specimens disregarding the non-failed ones. The first to fail approach may be used at a large scale sample of which each specimen represents the same weld details. The test is stopped at the first failure of a specimen. The n to fail approach is used in similar conditions as the first to fail one, when repairs of crack details can be performed during the test.

Each time when a detail fails, the test is stopped and the failed detail is repaired. Repairs are stopped depending of test conditions. At the end possibbly all details have failed and thus the all failed approach is applied. If only n specimens out of the N size of the sample failed, the n to fail approach is used.

This chapter considers the most common all failed approach. Other approaches and details of statistical analysis are considered in appendix 6. The following test result data should be documented according to the selected approach:. The mean of the log of number of cycles at failure of all n failed samples or details.

The number of cycles of the first failed detail within n tested details. The number of cycles of the first p failed details within n tested details. The tests should be performed according to well established and appropriate procedures or standards [32]. For the evaluation of service tests, an estimate of the standard deviation of logN has to be made, taking into account that the standard deviation varies with the life cycle of the component to be assessed, see fig. Here special verification procedures are recommended, see ref [32yy].

The factor F may be further modified according to safety requirements as given in chapter 5. Each element has to fulfill the acceptance criteria as defined in 4. The partial safety factors F and M may be selected from appendix 6. The effectivness of statically over-determined hyperstatic behaviour or redundancy of structural components, the possibility of detection of failures in individual structural parts and the possibility of repair determine the level of safety required in the individual structural parts.

So, no general recommendation can be given. It is recommended that the factor F given in 4. The criteria for factoring the observed life cycles for the test depend of the application. It is recommended to establish agreement on the factor F. The required survival probability is dependent on the a b c uncertainties and scatter in the fatigue assessment data, safety strategy and consequences of failure.

The uncertainties of fatigue assessment data may arise from fatigue actions, such as 1. These uncertainties are covered by an appropriate partial safety factor for the fatigue actions F, which is not considered here. Uncertainties of fatigue assessment data arising from fatigue resistance and damage calculation are: 4. The sources of uncertainty numbered 4. For normal applications, they are already covered in the fatigue resistance data given here. For special applications, the data may be modified by the selection of an adequate partial safety factor M.

The definition of a fatigue strategy refers predominantly to the method of fatigue analysis, inspection and monitoring in service. No regular monitoring in service is specified. So a high survival probability has to be provided. For fatigue actions which are almost uniform and act at very high cycles this strategy may be adequate. No regular monitoring in service is specified, so a high survival probability has to be provided. No regular monitoring in service is provided. In case of a fatigue failure, redistribution of forces provides an emergency life, so that the failure can be detected and repaired.

The welded joints can be designed for a normal survival probability. Fracture mechanics is used to calculate the life cycles until failure. From the number of life cycles, regular inspection intervals are derived. A normal probability of survival is adequate. Thus, no general recommendation can be given.

The safety factors are given in terms of stress. If safety factors are needed in terms of cycles, 'M may be calculated using the slope m of the resistance S-N curve. It should be recognized that the slope m of the S-N curve varies with the number of cycles, see fig. An example of a possible table of partial safety factors is given in appendix 6.

The weld quality should be equal to quality class B according to ISO However, some exceptions may be allowed in the tables given in chapter 3. Besides regulations and quality codes, the general standards of good workmanship have to be maintained. Before any start of repair actions, it is vitally important to establish the reason for the damage. This will influence the decisions to be made about the need for repair and for the repair methods. Possible reasons for fatigue damage may be:. In most cases of damage, design, loads and imperfections are the governing parameters of the failure, material properties are often secondary.

The actions to be taken should be based on the results of the investigations. Possible actions are:. They are not normative. Then the numbers occurrence of transitions reversals from one extreme value peak or through to another are counted and summarized in the matrix. A number in the matrix element ai, j indicates the number of transitions from a stress belonging to class i to a stress belonging to class j. A time signal for fatigue tests or crack propagation simulations or cumulative frequency diagrams stress spectra for damage calculations can be generated from the transition matrix by a Markov random draw.

The stress signal, looked at vertically, is regarded as the pagoda roof. A cycle is obtained, when a contour is closed by the drop of the flow from a peak to a slope of the roof [26 and 27]. The range is then equal to the difference between the extreme values of the contour. Later the smaller included cycles can be determined the. The non closed contour from the extreme of the entire signal leads to a half cycle. Reservoir counting is similar.

Here, the Mk-factors are derived from the non-linear stress peak distribution Fnlp x along the anticipated crack path x assuming no crack being present. Hence, the function of the stress concentration factor kt,nlp x can be calculated. The integration for a certain crack length a yields:. For different crack lengths a, a function Mk a can be established, which is preferably presented in the form:.

The interaction between adjacent cracks should be checked according to an interaction criterion. There are different interaction criteria, and in consequence no strict recommendation can be given. It is recommended to proceed according to an accepted code, e. For the majority of cases, the formulae given below are sufficient. Through the wall cracks in curved shells under internal pressure In sphere and longitudinal cracks in cylinder loaded by internal pressure.

Mk covers increase of stress concentration factor due to bulging effect of shell. For details see ref. For more details see ref. For a variety of welded joints parametric formulae of the Mk functions have been established and published [18,19]. For the majority of cases, the formulae given below are sufficient [20]. A systematic set of formulae was also developed in [xx] using the procedure outlined in chapter 6. The formulae are valid within the given dimensional validity ranges.

Longitudinal non-loadcarrying attachment Dim. Relates to remotely loaded unrestraint joints. The tanh correction allows for reduction of angular misalignement due to the straightening of the joint under tensile loading. It is always 1 and it is conservative to ignore it. Ideally, all effects have to be considered, e. For design, a safety margin is considered, which is applied to the mean values.

The values used for design are the so called characteristic vakues index k. Taking into account that the probability distribution of the mean corresponds to a Student law t-distribution and the probability distribution of the variance corresponds to a Chisquare law P2 , the general formula for ki is given by:.

If the variance is fixed from other tests or standard values, no confidence interval has to be considered and so the factor is given by:. Starting from the formula in 4. Taking the acceptance criterion from chapter 3. With the formula for k the different values of F can be calculated, depending on number of test specimens n and on the assumed standard deviation Stdv of the test specimens in terms of logN.

Testing all test specimens simultaneously until first failure When all test specimens are tested simultaneously until the first to fail, only one value of log NT is obtained and no standard deviation can be derived from test results. When considering statistical evaluation, account must be taken of additional effects as illustrated in fig. The mean sample xm is therefore given by:.

The different values of F can be calculated, depending on number of test specimens n and on the assumed standard deviation Stdv of the test specimens in terms of log N. Testing all specimens simultaneously untin n failures amongst m specimens Under development from IIW doc.

For special fields of application, tables of safety factors may be established. Second edition Niemi E. Recommendations concerning stress determination for fatigue analysis of welded components. IIW doc. Fatigue of Welded Structures. Fatigue Strength of Welded Structures. Design and analysis of fatigue resistent welded structures Abington Publishing, Abington Cambridge, U. Design recommendations for cyclic loaded welded steel structures IIW doc.

Structural hot spot stress procedure: [7] Huther M. Recommendations for hot spot stress definition in welded joints. Hot spot stress in cyclic fatigue for linear welded joints. Effective notch stress procedure: [9]. Petershagen H. Experiences with the notch stress concept according to Radaj transl. Welded connection I: Fatigue assessment of welded connections based on local stresses transl. Forschungskuratorium Maschinenbau, Bericht No. Fracture mechanics: [13] Murakami Y. Stress intensity factor equations for cracks in three-dimensional finite bodies.

I - I Newman J. Stress intensity factors for internal surface cracks in cylindrical pressure vessels. Journal of Pressure Vessel Technology, , pp. An empirical stress intensity factor equation for the surface crack. Engineering Fracture Mechanics, vol Frank K.

Fatigue strength of fille welded cruciform joints. Stress intensity factors of welded joints. Engineering Fracture Mechanics, vol 46 , no 2, pp. Maddox S. Fatigue strength modifications: [21] rjaster, O. Effect of plate thickness on fatigue of welded components. XIII Weld imperfections: [22] [23] IIW guidance on assessment of the fitness for purpose of welded structures. SST Hobbacher A. Recommendations for assessment of weld imperfections in respect of fatigue. Weld quality specifications for steel and aluminium structures. Welding in the World, Vol. Stress spectrum: [26] Endo T. Fatigue of metals subjected to varying stress - prediction of fatigue lives transl.

Memoir Kyushu Institut of Technical Engineering, ASTM E Damage calculation: [28] Palmgren, A. On life duration of ball bearings transl. Cumulative damage in fatigue. September Haibach E. Modified linear damage accumulation hypothesis considering the decline of the fatigue limit due to progressive damage transl. Laboratorium fr Betriebsfestigkeit, Darmstadt, Germany, Techn. Cumulative fatigue by fracture mechanics. Fatigue testing: [32] Lieurade H.

XIII page Marque por contenido inapropiado. Carrusel Anterior Carrusel Siguiente. Buscar dentro del documento. Hamburg, Germany Suggestions for a future refinement of the document are welcome and should be addressed to the chairman: Prof. Misalignment Modified nominal stress Nominal stress Nonlinear stress peak The stress component of a notch stress which exceeds the linearly distributed structural stress at a local notch.

In the following cases, detailed fatigue assessment is not required: a The highest nominal design stress range satisfies M should be taken from an applicable design code. This is primarily the case in: a b complicated statically over-determined hyperstatic structures structural components incorporating macrogeometric discontinuities, for which no analytical solutions are available Using FEM, meshing can be simple and coarse.

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Identification of the critical points hot spots can be made by: a b c measuring several different points analysing the results of a prior FEM analysis experience of existing components, which failed 2. See also figure 2. Browse subjects Browse through journals Browse through conferences Browse through e-books. Electronic books The e-book database EBC. Reading desks and facilities Computer workstations Printing — photocopying — scanning Wireless LAN Interactive whiteboards Study cubicles Workstation for the blind and visually impaired. Course reserves Setting up a course reserve Form for setting up a course reserve.

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