Fatigue is a major concern in the design of structural components. Overview to critical plane approach to multiaxial fatigue. A multiaxial fatigue theory including mean stress and. Figure 7 also suggests that the swt fatigue parameter has a correlation coefficient of r 0.
An elasticplastic analysis of contact stresses in a pressfitted shaft in contact with a boss was conducted by finite element method and microslip due to the bending load was analyzed. Introduction a vast range of methods for multiaxial fatigue. A critical planeenergy model for multiaxial fatigue life. Jan 11, 2018 overview to critical plane approach to multiaxial fatigue. Introduction a vast range of methods for multiaxial fatigue prediction has been proposed in recent decades. The criteria have been divided into three groups, according to the fatigue damage parameter used in the criterion, i. Test specimens were machined in an hourglass shape from extruded rods.
Cyclic tests were carried out in a biaxial servo hydraulic machine under strain control at room temperature. Implementation of multiaxial fatigue theory in fe packages article pdf available in key engineering materials 719. The deviatoric stresses are the components of stress that deviate from the hydrostatic stress. Different from the uniaxial fatigue problem, the multiaxial fatigue problem is more involved due to the complex stress states, loading histories and different orientations of the fatigue crack in the components. The crack may then propagate in a direction perpendicular to the direct stress. Many multiaxial fatigue models have been proposed in the last decades 1. In this paper fretting fatigue life of pressfitted specimens was evaluated using multiaxial fatigue. Information about the openaccess article pressure vessels design methods using the codes, fracture mechanics and multiaxial fatigue in doaj. Life prediction under the conditions of triaxial variable loading remains an. The theory is a merger between the sines criterion and the statistical approach made by weibull. Most of the fatigue life estimates were within factoroftwo boundaries.
Next, the experimental setup and procedure are described in section 4, followed by the numerical model of the structure and the vibrationfatigue analysis in section 5. Among several parameters and constants the shear stress amplitude is one of the most important parameters in the formulations of the multiaxial fatigue damage models, in high cycle fatigue. By applying the multiaxial fatigue life prediction equation without mean stress effect to fatigue limit case, a simple fatigue limit prediction equation can be obtained. In an elastoplastic regime, a material which experiences a stresscontrolled cyclic loading with a nonzero mean stress, will exhibit an. Moreover, for multiaxial fatigue stresses, the criterion must take into account the variable principal stress direction, see fig. Critical plane approach to multiaxial variable amplitude. Nonproportional low cycle fatigue of 6061 aluminium alloy under 14 strain paths t. Pdf implementation of multiaxial fatigue theory in fe packages. The direction and amplitude of principal stress and strain vary over a period of time results in nonproportional cyclic loading on the component. When the fretting occurs in the pressfitted shaft, the fatigue strength remarkably decreases compared with that of without fretting. Multiaxial fatigue and fracture, volume 25 1st edition. The work is motivated by a need to predict crack initiation life in tires, based on strain histories obtained via finite element analysis. Pdf life prediction techniques for variable amplitude. In conttrast, strain based criteria, such as the octahedral shear strain theory.
Dec 23, 2014 the theory is a merger between the sines criterion and the statistical approach made by weibull. These proposals are based on the concept of volume influencing fatigue crack initiation. Pdf many mechanical or structural components are subjected to multiaxial, irregular cyclic loading during service. More specifically, multiaxial loading will result in a state of stress andor strain, which manifests as two or more components in the stress or strain tensor. Multiaxial assessment the fatigue properties of a metallic material are determined from a set of fatigue tests, normally under axial load and in displacement strain or load control. The multiaxial criteria that will be investigated and compared later in the thesis are outlined. On the basis of the two local mesoscopic approaches of papadopoulos, two new nonlocal high cycle multiaxial fatigue criteria are developed. A comparative analysis of some fatigue models is also presented. The tests can be performed in tension, compression and bending, with adjustable.
Focus will be on high cycle fatigue at multiaxial stress states. Studies show that around 80% of mechanical failures are caused by. Following this introduction, a survey of fatigue criteria found in the literature is presented. Multiaxial fatigue life prediction on s355 structural and. Fatigue life evaluation of pressfitted specimens by using. Multiaxial fatigue simulation of an az31 magnesium alloy. The determination of long life fatigue characteristics was the object of much of the early research in multiaxial fatigue.
A comprehensive account of the mcmiiv items can be found in appendix a. Evaluation of stressstrain models and fatigue life prediction methods under proportional loading 371 slr sl. In the shrink or pressfitted shafts such as railway axles, fretting can occur by cyclic stress and microslippage due to local movement between shaft and boss. Abstract a theoretical development based on a simple physical model is proposed to help the designer predict high strain multi.
Browna theory for fatigue failure under multiaxial stressstrain. Mar 18, 2020 by applying the multiaxial fatigue life prediction equation without mean stress effect to fatigue limit case, a simple fatigue limit prediction equation can be obtained. From the principle that the damage associated with the initiation of fatigue microcracks cannot. In part one of this twopart paper, a multiaxial nonproportional cycle counting method and fatigue damage calculation procedure are proposed, which is compared with one published damagesearching method. Critical plane analysis refers to the analysis of stresses or strains as they are experienced by a particular plane in a material, as well as the identification of which plane is likely to experience the most extreme damage. A nonlocal theory for the assessment of multiaxial high. A theory for the effect of mean stress on fatigue of metals under combined torsion and axial load or bending, journal of engineering for industry, nov. Uniaxial damage models cannot be 6 reliably applied in this case. Multiaxial fatigue is a critical problem for many mechanical and structural components and accurate life prediction is important to ensure the long term integrity of these components. This allows many possible applications for magnesium alloys subjected to multiaxial fatigue. Many components have multiaxial loads, and some of. Multiaxial fatigue theories can be classified into three main groups. Introduction multiaxial fatigue loading in welded joints generally refers to normal stresses. Multiaxial fatigue research condacted on metals has been under biaxial loading.
Fatigue cracks usually initiate from the surface of a component figure 1. The basic theory of random processes, structural dynamics and fatigue analysis is presented in section 2. Aug 29, 2018 in the present work, we propose a robust calibration of some bi. A theory for fatigue failure under multiaxial stressstrain. Theoretical anchoring the mcmiiv has a very strong link to personality theory in that each of its personality pattern scales is an operational. Introduction it is known that a large number of components and equipment in machine construction are subjected to multiaxial stresses variable in time. In the present work, we propose a robust calibration of some bi. Multiaxial fatigue of a railway wheel steel 1221 journal of engineering science and technology september 2015, vol. Multiaxial fatigue an overview sciencedirect topics.
Fatigue design of structural components under multiaxial loading often relies on fatigue. A theory for fatigue failure under multiaxial stress. An example of a stress based multiaxial fatigue life. Studies show that around 80% of mechanical failures are caused by fatigue 5. Available fretting fatigue experiments conducted on a cylinderonflat contact configuration made of al4%cu alloy were used to evaluate the methodology.
Mean stress and plasticity effect prediction on notch. A nonlocal theory applied to high cycle multiaxial fatigue. Multiaxial fatigue crack initiation in rubber tire science. Mean stress and plasticity effect prediction on notch fatigue. Multiaxial fatigue crack initiation in rubber tire. Some other test configurations may be used such as rotating bend tests. A useful concept in multiaxial fatigue and especially in plasticity is that of deviatoric stresses. Background fatigue theory the aim of this chapter is to establish the basis for other chapters. By using a large number of experimental data of metallic materials reported in literature, it has been proven that the fatigue limit prediction equation is not only simple in. For the derivation of the subsurface stresses for line and point hertzian contact, please refer to refs.
Among several parameters and constants the shear stress amplitude is one of the most important parameters in the formulations of the multiaxial fatigue damage models, in high cycle fatigue regime. The compared multiaxial criteria are presented in section 3. It may be represented graphically by contours of constant life, which are expressed mathematically by. The analysis of fatigue is based on multiaxial cyclic plasticity, notch correction and damage estimations. Theories article pdf available in journal of engineering materials and technology 1183 july 1996 with 1,064 reads. The approach based on the strain energy density sed averaged over a control volume is first used to summarise uniaxial and multiaxial fatigue strength data of welded joints made of structural steel and aluminium alloys. At the endurance limit of n stress cycles the criterion is written as. Welded joints, multiaxial fatigue, notch stress approach.
Besides the need for multiaxial damage models, another key issue to reliably. Both theories are based on critical plane concepts. Pressure vessels design methods using the codes, fracture. This approach hypothesises that the maximum shear strain. A multiaxial fatigue limit prediction equation for metallic. There have also been some trials for the generalization of the existing theories. An incremental multiaxial life prediction law imlp is proposed which consists of the threedimensional thermoviscoplasticity theory based on overstress tvbo combined with a multiaxial damage accumulation law mda to compute the lifetime or cyclestocrack initiation.
Next, the experimental setup and procedure are described in section 4, followed by the numerical model of the structure and the vibration fatigue analysis in section 5. A multiaxial fatigue criterion must first satisfy the invariance condition. Pdf a damage mechanics approach to multiaxial fatigue. This introduces the problem of the prevalence of random multiaxial loading in the service environment of mechanical components. The main aim is to develop a theory that is to predict the fatigue life of defined. Extensive models have been proposed for the multiaxial fatigue life prediction in the past, especially during the past two decades. It may be represented graphically by contours of constant life. Often the loads may result in a multiaxial stress state.
Thermomechanical deformation behaviour of in 738 lc and sc 16 j. Miller observed that fatigue life under multiaxial conditions is governed by the experience of the plane receiving the most damage, and that both tension and shear loads on the critical plane must be considered. Implementation of multiaxial fatigue theory in fe packages. A multiaxial stressbased critical distance methodology to. Life prediction techniques for variable amplitude multiaxial fatiguepart 1. Multiaxial fatigue university of illinois at urbana. However, in the case of outofphase multiaxial fatigue, tf and mf change during one cycle of loading, so that this. Multiaxial vibration fatigue a theoretical and experimental. A new theory for multiaxial fatigue is presented that is based on a physical interpretation of the mechanisms of fatigue crack growth. Extensive models have been proposed for the multiaxial fatigue life prediction in. This paper describes a new model for predicting multiaxial fatigue crack initiation in rubber. Many mechanical or structural components are subjected to multiaxial, irregular cyclic loading during service. Ali fatemi university of toledo all rights reserved chapter 10 multiaxial fatigue.
Can the conventional highcycle multiaxial fatigue criteria be re. Design of experiments for validation of multiaxial high cycle. In this paper fretting fatigue life of pressfitted specimens was evaluated using multiaxial fatigue criteria based on critical plane approaches. The sines criterion 8 sines proposes a global fatigue criterion under multiaxial stress condition by defining a fatigue function of the form. It is well known that the fatigue process is sensitive to superposed tensile mean stress in both the highcycle and lowcycle fatigue regimes. Modern procedures for critical plane analysis trace back to research published in 1973 in which m. Critical plane analysis is widely used in engineering to account for the effects of cyclic, multiaxial load histories on the fatigue life of materials and structures. Pdf implementation of multiaxial fatigue theory in fe. Evaluation of multiaxial stressstrain models and fatigue.
J2a is the second invariant of stress tensor pm is the average hydrostatic stress. Multiaxial fatigue testing machine dimensions general description the system for multiaxial fatigue testing allows to run creep and fatigue testing of products and materials. Multiaxial fatigue is a general term that may be used to describe loading andor loading plus geometry conditions resulting in complex states of stresses and strains, either locally or globally. Cyclic fatigue damage characteristics observed for simple. Design of experiments for validation of multiaxial high. Contrary to most classical fatigue phenomena, rolling contact fatigue is typically a multiaxial fatigue mechanism. In this work it is studied the lowcycle fatigue behavior of the magnesium alloy az31b at several total strains under uniaxial and multiaxial cyclic loading conditions. An incremental life prediction law for multiaxial creep. The earliest works on multiaxial stress states, although under monotonic loading, relate to classical yield theories of lame and. A multiaxial fatigue limit prediction equation for.
1228 668 1315 1068 225 194 1347 1288 988 423 296 1057 709 1465 1390 1172 1203 474 741 410 1237 1483 1437 436 196 165 822 139 895 350 450 358 416 1434 1209 399 800 105