On the other hand, although the typical cyclicstress-strain curves could also be described by the Hollomon equation, the ﬁtting precision might not be high enough with unsatisfactory correlation coefﬁcient, especially for the insufﬁcient stabi- lized hysteresis loops. Seen from eq. (4), theoretically, the ﬁtted cyclicstress-strain curve could be obtained based on merely three stabilized hysteresis loops, in other words, if the stabilized cyclic stresses could be accurately calculated by merely three strain amplitudes and stabilized stresses, the work amount to obtain the cyclicstress-strain curve would be signiﬁcantly reduced. To investigate the feasibility of the proposed ﬁtting method, the stabilized cyclic stresses at various strain amplitudes were tested by using the proposed tensile-fatigue device. During the tests, the low cycle fatigue loading rate, namely the tensile and compressive rate, was set as constant 5 µm / s. When the strain amplitude was 0.0058, the stabilized cyclicstress under stable condition was 182.1 MPa, when the strain amplitude increased to 0.014, the
Abstract. Aluminum Alloy wheels has superior thermal conductivity. (>150 watts per kelvin per meter) than Steel (45 watts per kelvin per meter) ,generally lighter offering more structural strength, improve handling by reducing unsprung mass, allowing suspension to follow the terrain more closely and improve grip. Alloy wheels offer better corrosion resistance, do not rust internally like steel wheels and thus last the life of a vehicle. This paper presents the modeling and simulation results of modeling and cyclic stresses analysis of wheel rim. Now a day’s light alloys wheel materials are used in vehicles. To improve the quality of wheel rim evaluate in the cyclicstress life of wheel proposed in this project. In this paper we designed the rim from the Prevailing dimensions by Pro-E Solid modeling software which one is suitable for wagons wheel rim material can be analyzed by using NX NASTRAN software. Main aim is to reduce the unplanned brake failure due to overheating Lighter wheels can improve hold by reducing unsprung mass, Countenancing suspension to survey the terrain more closely and thus improve grip, conversely not all alloy wheels are lighter than their steel equivalents. Wheels are endangered to a high freight. Therefore, it is obligatory to observe a wheel for both strength and cyclicstress struggle, Further we can do optimization of material thickness to moderate the material consumption. Supplementary we can improve life of component by using Progressive cyclicstressstrain life approach.
Aim of the current study is to test applicability of the existing and proposed design criteria. For that purpose we selected a material batch, which would have been ready for plant use, e.g., in a PWR surge line. An experimental strain life fatigue curve was determined to be used as a base line for component specific evaluations and for comparison with the Langer and Chopra curves, which are the basis of the ASME III and NRC RG 1.207 design curves. Monotonic and cyclicstressstrain responses were carefully analyzed to clarify the deformation and fatigue mechanisms for this steel.
Abstract. Soils have an anisotropic response, and changing the inclination () and magnitude of the major principal stress will aect collapse potential and brittleness, as well as shear strength and shear stiness. In this paper, the eect of the stress path, with changes in intermediate principal stress, on the dynamic behavior of Babolsar sand, is studied. A series of undrained monotonic and cyclic tests on loose sand with induced anisotropy were conducted by using automatic hollow cylinder apparatus. Special attention was paid to the signicant role of the intermediate principal stress parameter (b) in the deformation behavior of the sand during cyclic loading. Results show that at constant , conning stress and fabric, variation in b has a signicant eect on strain amplitudes, but will not change the contractive or dilative behavior of specimens. Variation of b has a great eect on liquefaction resistance but has no eect on the mobilized friction angle at steady state. It is shown that conning stress has a signicant eect on soil response (strain development, excess pore water pressure generation and shear modulus and damping ratio). Moreover, by increasing the conning stress, the eect of b value on cyclic behavior is more pronounced.
exercised at a high strain magnitude indicate that the mechanical load applied to the leg exercised at a low tendon strain magnitude did not influence the existing internal tensional homeostasis of the tendon cells regulating the anabolic or catabolic responses. The results further show that the mechanical load exerted on the Achilles tendon during the low- strain-magnitude exercise is no more a sufficient stimulus for triggering further adaptation effects on the Achilles tendon than the stimulus provided by the mechanical load applied during daily activities. Furthermore, our findings indicate that the 4.55% strain applied during the high-strain-magnitude intervention was above the homeostatic calibration point and thus was sufficient to elicit a homeostatic perturbation at the Achilles tendon that triggered anabolic cell responses, causing the changes observed at the tendon–aponeurosis strain–force relationship and the region-specific hypertrophy of the tendon. In the present study, we controlled the strain magnitude, strain frequency and the exercise volume but not the strain rate during the interventions. The participants achieved the target moment as fast as possible and, therefore, the strain rate should not be very different between the two examined interventions. However, based on our experimental design it is not possible to investigate a potential effect of the strain rate on the tendon adaptational responses that we discovered.
Our hypothesis for the different damage distributions is related to how the spread of the rarefaction fans originating in the flyer-plate (and the sample, but this is constant be- tween these experiments) a ff ects both the volume of sam- ple pulled into tension, and the time spent under tension. As the two colliding fans intersect, the stress in the sam- ple will be reduced from compression, through zero, and into tension. In the case where the fan has a large spread, as with the tantalum flyer-plate, this process takes longer to distribute throughout the entire sample, instead remain- ing in a smaller region. Hence the tensile stress is more concentrated, there is less material volume to accommo- date the plasticity resulting from the stress, and a narrow band of extreme damage will form. In the quartz flyer- plate experiments, while the applied tensile stress will be very similar to that in the tantalum cases, the stress is more quickly distributed across a larger volume of material, and the damage remains in the void nucleation phase. To demonstrate this graphically, hydrocode simulations were performed.
High strain magnitude and low strain frequency are important stimuli for tendon adaptation. Increasing the rate and duration of the applied strain may enhance the adaptive responses. Therefore, our purpose was to investigate the effect of strain rate and duration on Achilles tendon adaptation. The study included two experimental groups (N=14 and N=12) and a control group (N=13). The participants of the experimental groups exercised according to a reference protocol (14 weeks, four times a week), featuring a high strain magnitude (~6.5%) and a low strain frequency (0.17 Hz, 3 s loading/3 s relaxation) on one leg and with either a higher strain rate (one-legged jumps) or a longer strain duration (12 s loading) on the other leg. The strain magnitude and loading volume were similar in all protocols. Before and after the interventions, the tendon stiffness, Young’s modulus and cross-sectional area were examined using magnetic resonance imaging, ultrasound and dynamometry. The reference and long strain duration protocols induced significantly increased (P<0.05) tendon stiffness (57% and 25%), cross-sectional area (4.2% and 5.3%) and Young’s modulus (51% and 17%). The increases in tendon stiffness and Young’s modulus were higher in the reference protocol. Although region-specific tendon hypertrophy was also detected after the high strain rate training, there was only a tendency of increased stiffness (P=0.08) and cross-sectional area (P=0.09). The control group did not show any changes (P=0.86). The results provide evidence that a high strain magnitude, an appropriate strain duration and repetitive loading are essential components for an efficient adaptive stimulus for tendons.
The components of the three traction vectors, i.e. the stress components, can now be displayed on a box element as in Fig. 7.2.3. Note that the stress components will vary slightly over the surfaces of an elemental box of finite size. However, it is assumed that the element in Fig. 7.2.3 is small enough that the stresses can be treated as constant, so that they are the stresses acting at the origin.
experimental results available in ^literature. This was necessary because Sjostrom did not perform any experimental measurements of thermal stress. The results obtained from Sjostrom's model indicated a significant level of discrepancy with experimental results obtained by others, but the inclusion of transformation plasticity has reduced this discrepancy. The calculated residual stresses at the surface in the axial direction were compressive. The level of these stresses fell in the interior of the specimen and finally they were reversed towards the centre. Hence, a maximum compressive stress at the surface and a maximum tensile stress in the centre were predicted. Sjostrom has also examined the effect of the degree of memory of plastic history in the earlier stages of the quench on the stress generation process. He suggested a complete loss of this memory in the case of kinematic hardening and no loss in case of isotropic hardening. No experimental evidence of such a memory effect has been mentioned and the effect of viscous flow on the stress generation process was also not taken into consideration.
Abstract In this paper is studied a vibratory conveyor that is placed on an elastic base. Using the closed contours method it was determined the system that needs to be solved to obtain graphical representation for the generalized coordinates determining the position of the mechanical system elements. The shaking conveyor represents the chase hanged or supported to the fixed section. The chase commits oscillating motions hereupon the cargo which is in the chase, migrates concerning to the chase. The nature of the flow and its parameters are determined by the nature of the oscillating committed by the chase. Justifying the dynamic parameters of the shaking conveyor and a study of the stress-strain state. Installation causes fluctuations fixed tray. Uniformly distributed load on the tray acts in each element of the mechanism. On the basis of the program APM structure 3D investigated the stress-strain state and determined movement of each link mechanism with results and calculations.
The strain-life approach is an alternative to the stress-life approach for determining fatigue damage, particularly when yielding occurs. An online temperature-modified strain-life approach has been developed and verified through several TMF tests. The spring-slider model has been developed and verified to enable local temperature- stress-strain trajectory modelling. The model is applicable if the strain is controlled or else the model given in  can be used. Reversal point filtering turned out to be acceptable for elasto-plastic hardening solids. The high computational speed of the classical strain-life approach can thus be preserved. The developed model is a generalization of the Skelton  findings and is formally well defined through an operator of the Prandtl type. Although neither creep damage nor some other effects can be assessed by the proposed approach, an improved temperature-stress-strain state prediction based on standardized LCF tests is possible.
At Fig. 5 the vertical stress in Pa is presented and at Figs 6 a,b,c the shear stresses in Pa are presented. The von Mises (Fig. 7) and the principal stresses (Fig. 8) have a great expressive value for specialist in maxillofacial surgery. The von Mises stress is a mathematical combination of all components of both axial and shear stresses. The principal stresses inform us about stresses in directions of the principle axes. They can be usually used to describe the stresses in the studied mandible, and, therefore, they are reasonable indicators, where failures and fractures can later occur. The maximal von Mises stresses in the mandible are located in dorsal part of column mandilble, in the area of the artificial prosthesis and in alveolar processus of corpus mandible. We
Abstract. The article presents calculation results for model elastic problem of defining stress-strain state of a deep beam preformed in 3D and 2D statements with the use of ANSYS software package. Geometric relations are taken in the form of Cauchy equations. The purpose of the study is to assess error in the results obtained for the two statements and to draw a conclusion on the possibility of using 2D statement for the deep beam under study. Based on 3D statement calculation results one may observe a short area near the support surface of a deep beam with the maximum load across the entire thickness. In this area the concentration of maximum stress values and maximum linear and angular deformations in the structure material are observed. The area is located on the axis of symmetry of the deep beam near the inner edge of support surface. It is found that the stress intensity values obtained for the two statements have considerable differences in this area, for that reason 3D statement shall be used when performing calculations for the deep beam. This way of solving the problem is illustrative of stress-strain state parameters distribution across the thickness of the structure, which is necessary for its strength evaluation.
consolidated specimen height . It is important to maintain the strain rate when comparing test methods. A direct simple shear has the same initial stress state as a direct shear test but avoids the stress concentration occurrence seen with direct shear. The dilatancy component normally disappears when there is no increment of volume after failure occurs . When the stress-strain curves become horizontal, then the friction component is active. For low organic contents and drained test condition the stress-strain behaviour was influenced primarily by the mineral fraction. Soil shear strength may be defined as the shear stress over stressstrain. Based on Anggraini (2006), the magnitude of strain depends on load, composition of soil, pass stress history and void ratio . Simple shear is in cylindrical shape that has a series of thin brass confining rings. It obtained more homogenous distribution to shear and normal stresses, and resulting strains. Besides that, the purpose is to apply the specimen with a simple shear strain deformation . Direct simple shear test can shear a soil to unlimited displacement without creating a substantial non-uniformity in stress and strain distributions. It also allows the shear deformation to be distributed uniformly through the sample because of confining rings. Direct shear box is the straightforward and simplest test to determine behaviour of soils. Specimen inside the direct shear box is sheared along the center of the specimen at horizontal plane and shows that the failure plane is horizontal. The specimen is in square shape. There’s been a criticized on the direct shear box that relate to the non-uniformity of stress-strain throughout the specimen because of rigid platens that used to confine the specimen as stated from Saada & Townsend (1981) . Besides that, the shearing happens when one half of the box moves relative to another and will create failure in soil specimen. It might fail the soil on the designated plane, which may not be the weakest one.
environment in which racial encounters are shared and reassessed (Jean and Feagin 1998). In this way, each family member pays the price of the experience of their kinfolk. They also highlighted that in some cases, male workers’ feelings of indignation and humiliation resulting from their experiences of racism at work turn into spouse abuse due to a displaced rage. This involves husbands venting their anger on their wives at home instead of reacting angrily to racist encounters with their White colleagues and bosses at work. This displaced rage was found to ruin marital relations between the spouses through increased conflict and separation. In short, wives were affected through listening to their husbands’ pain, and by being the target of their husbands’ anger and its related negative marital consequences (Jean and Feagin 1998). However, this study was neither exclusively about racism at work nor about the inter-spouse stress and strain transfer process; and did not have access to data from both spouses 3 , as it is a secondary data analysis of Feagin and Sikes study about African-American middle-class professionals’ experience of racism (Feagin and Sikes 1994), so its findings can be argued to be less than comprehensive.
Interestingly, all stressors and combinations of stressors that obstructed memory formation in ‘ smart ’ snails enhanced memory formation in ‘ average ’ snails (see Table 1). However, there were two individual stressors, CE (or 5-HT as proxy) and KCl, that enhanced memory in ‘ average ’ snails, but did not obstruct memory in ‘ smart ’ snails. Activation of the 5-HT predator detection pathway, through either a 5-HT injection or training in CE, warns a snail that a predator is nearby. Although a direct comparison between freshly collected ‘ smart ’ and ‘ average ’ snails has not been made before, response to predators is highly conserved among strains of L. stagnalis (Orr et al., 2009a,b; Dalesman and Lukowiak, 2012). From an evolutionary perspective, it is logical that the ability to form memory surrounding a predator encounter is preserved across strains to promote survival, regardless of cognitive ability (Kotrschal et al., 2013; Simpson et al., 2016). Exposure to KCl elicits the WBWR in snails. This response is a snail ’ s last-resort defense mechanism. We have observed, in the laboratory, that when facing imminent predation by a crayfish (i.e. being in the crayfish ’ s grasp), a snail will display the WBWR. Thus, from an evolutionary perspective, it follows that it would be advantageous for preservation of memory surrounding an experience when the WBWR is elicited, such as exposure to KCl. This response is only triggered in situations that a snail perceives as life threatening. Interestingly, when KCl and activation of the predator detection pathway are combined as stressors, ‘ average ’ Dutch snails form enhanced memory that is susceptible to a propranolol block of reconsolidation (Hughes et al., 2016). This ability to make a 24 h memory also occurs with either the KCl bath or predator detection alone, but with just the single stressor exposure, propranolol does not obstruct reconsolidation (Hughes et al., 2016). In contrast, the ability to form memory is obstructed in ‘ smart ’ snails when both stressors are applied. Again, this result may be understood in the context of the YDH law. Although the effects of predator detection and full-body withdrawal on memory may generally be more conserved between strains than other, non-imminently life-threatening stimuli, perhaps there is still a threshold of ‘ too much stress ’ . This threshold could explain why, when both are combined, ‘ smart ’ snails, which are either at a higher basal level of stress than ‘ average ’ snails or are more sensitive to perceiving stress, are unable to form memory.
Strength calculations for structural parts and elements with various stress concentrators as part of the classical concepts of continuum mechanics (CM), as a rule, lead to unreal stress values in the neighbourhood of singular points in terms of strength characteristics. This is caused by the use of the hypothesis of continuity. While the cut curvature radius is large enough in comparison with the crystals of the matter, it has no effect on the stress distri- bution, but if the curvature is commensurate with the crystal sizes, the questions of whether it is reasonable to use the classical theory of elasticity arise.