Energy Versus Stress Theories for Combined Stress—A Fatigue Experiment Using a Rotating Disk

1961 ◽  
Vol 83 (1) ◽  
pp. 10-14 ◽  
Author(s):  
W. N. Findley ◽  
P. N. Mathur ◽  
E. Szczepanski ◽  
A. O. Temel
Keyword(s):  
Fatigue Failure ◽  
Strain Energy ◽  
Fatigue Cracks ◽  
Circular Disk ◽  
Rotating Disk ◽  
Constant Load ◽  
Combined Stress ◽  
Combined Stresses ◽  
Critical Location ◽  
Fatigue Experiment

An experiment is described in which the strain energy at the critical location for fatigue failure is maintained constant while the stresses on a given plane of the material at the same location are caused to fluctuate. Apparatus developed to produce this condition consisted of a circular disk with a wide flanged rim which was loaded along a diameter by means of pivot-pad bearings. The disk was then rotated under a constant load to produce the desired fluctuation in stresses at the center of the disk while maintaining a constant strain energy at the center. The fact that fatigue cracks were developed in the region of constant strain energy was considered to indicate that a concept of a fluctuating strain energy as a basic theory of failure by fatigue under combined stresses is not tenable.

A Note on the Shear Stress Criterion for Fatigue Failure under Combined Stress

1969 ◽  
Vol 20 (1) ◽  
pp. 57-60 ◽  
Author(s):  
R. E. Little
Keyword(s):  
Shear Stress ◽  
Fatigue Limit ◽  
Fatigue Failure ◽  
Failure Criterion ◽  
Basic Problem ◽  
Failure Criteria ◽  
Test Methods ◽  
Combined Stress ◽  
Stress Criterion

SummaryNishihara’s combined bending and torsion out-of-phase fatigue limit data are analysed. The Tresca shear stress failure criterion predicts strengths up to 30 per cent higher than observed. It thus appears that renewed attention should be given to the basic problem of developing reliable combined stress failure criteria. It is suggested that new test methods will be required for this purpose.

scholarly journals Down-Regulation of Cytokinin Receptor Gene SlHK2 Improves Plant Tolerance to Drought, Heat, and Combined Stresses in Tomato

Plants ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 154
Author(s):  
Naveed Mushtaq ◽  
Yong Wang ◽  
Junmiao Fan ◽  
Yi Li ◽  
Jing Ding
Keyword(s):  
Abiotic Stress Tolerance ◽  
Receptor Gene ◽  
Antioxidant Enzyme Activities ◽  
Plant Responses ◽  
Plant Tolerance ◽  
Combined Stress ◽  
Cytokinin Signaling ◽  
Down Regulation ◽  
Cytokinin Receptor ◽  
Combined Stresses

Environmental stresses negatively affect the growth and development of plants. Several previous studies have elucidated the response mechanisms of plants to drought and heat applied separately; however, these two abiotic stresses often coincide in environmental conditions. The global climate change pattern has projected that combined drought and heat stresses will tend to increase in the near future. In this study, we down-regulated the expression of a cytokinin receptor gene SlHK2 using RNAi and investigated the role of this gene in regulating plant responses to individual drought, heat, and combined stresses (drought + heat) in tomato. Compared to the wild-type (WT), SlHK2 RNAi plants exhibited fewer stress symptoms in response to individual and combined stress treatments. The enhanced abiotic stress tolerance of SlHK2 RNAi plants can be associated with increased membrane stability, osmoprotectant accumulation, and antioxidant enzyme activities. Furthermore, photosynthesis machinery was also protected in SlHK2 RNAi plants. Collectively, our results show that down-regulation of the cytokinin receptor gene SlHK2, and consequently cytokinin signaling, can improve plant tolerance to drought, heat, and combined stress.

Finite Elastic Deformation of an Annular Rotating Disk

1976 ◽  
Vol 98 (4) ◽  
pp. 375-379 ◽  
Author(s):  
J. B. Haddow ◽  
M. G. Faulkner
Keyword(s):  
Elastic Deformation ◽  
Strain Energy ◽  
Equations Of Motion ◽  
Strain Energy Function ◽  
Rotating Disk ◽  
Force Balance ◽  
Annular Disk ◽  
Incompressible Materials ◽  
Plane Stress Problem ◽  
Governing Differential Equation

An accurate approximate method for the solution of the generalized plane stress problem of finite elastic deformation of a rotating annular disk is given. The method is applicable to both compressible and incompressible materials. Use of the nonlinear governing differential equation is avoided by considering the disk to be an aggregate of discrete coaxial rings, equations of motion, force balance and compatibility relations being formulated for the rings. Results are given for neo-Hookean disks and disks of a compressible material which has a strain energy function proposed by Blatz and Ko [7].

Residual Stress and Strain Responses of Welded Piping Joints Under Low-Cycle Fatigue Loading

2009 ◽  
Author(s):  
Pei-Yuan Cheng ◽  
Tasnim Hassan
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Residual Stresses ◽  
Fatigue Failure ◽  
Welded Joints ◽  
Low Cycle Fatigue ◽  
Fatigue Cracks ◽  
Stress And Strain ◽  
Weld Toe ◽  
Strain Responses

It is well known that residual stress of welded joints influence their fatigue lives. This influence of residual stress is manifested through strain ratcheting response at the weld toe. Among many other reasons, strain ratcheting at the weld toe is anticipated to be a reason of many premature fatigue failure of welded joints. Hence, accurate simulations of weld toe residual stress and strain responses are essential for fatigue life simulation of welded joints. This paper presents results form an ongoing study on fatigue failure of welded piping joints. A modeling scheme for simulating weld toe residual stress and strain response is developed. Uncoupled, thermo-mechanical, finite element analyses are employed for imitating the welding procedure, and thereby simulating the temperature history during welding and initial residual stresses. Simulated residual stresses are validated by comparing against the measured residual stresses. Finite element simulations indicate that both residual stress and resulting strain responses near the weld toe are the key factors in inducing fatigue cracks at the weld toe. Research needs in revealing the fatigue failure mechanisms at the weld toe are discussed.

scholarly journals Limit analysis of beams under combined stresses

2008 ◽  
Vol 6 (1) ◽  
pp. 75-88 ◽  
Author(s):  
Marina Mijalkovic ◽  
Marina Trajkovic ◽  
Bojan Milosevic
Keyword(s):  
Bearing Capacity ◽  
Cross Section ◽  
Shear Force ◽  
Pure Shear ◽  
Bending Moment ◽  
Beam Cross Section ◽  
Combined Stress ◽  
Pure Bending ◽  
Combined Stresses

The problem of the determination of limit bearing capacity of beam cross section under pure bending, eccentric tension, pure shear, as well as combined stress is considered in this paper. The influence functions of the bending moment and axial force, as well as the bending moment, axial and shear force on the cross section limit bearing capacity in case of rectangular and I beam cross section are derived.

Ultimate Limit States of Piping Supports With Outer Diagonal Brace Under High Acceleration Sinusoidal Shaking Condition

2018 ◽  
Author(s):  
Ryuya Shimazu ◽  
Michiya Sakai
Keyword(s):  
Fatigue Failure ◽  
Static Load ◽  
Fatigue Cracks ◽  
Reaction Force ◽  
Maximum Load ◽  
Vibration Test ◽  
Central Research ◽  
Limit States ◽  
High Acceleration ◽  
Ultimate Limit

In this study, the fundamental mechanical inelastic behavior of piping supports was investigated in order to consider an effective elastic-plastic evaluation method. High-acceleration vibration tests were conducted using the resonance shaking table installed in Central Research Institute of Electric Power Industry (CRIEPI), and the ultimate limit states of piping supports under vibration conditions were observed. Each specimen had an outer diagonal brace. Buckling or fatigue failure occurred in the vibration test. Fatigue failure did not occur in the static load test. The static and dynamic skeleton curves were in agreement with each other when the failure mode was the same. When the response load did not reach the buckling load in the vibration test, fatigue cracks occurred after the stable response. The locations of the fatigue cracks tended to be where the local buckling occurred in the static tests. In both the vibration and the static load tests, even if the load decreased after the maximum load by buckling, the reaction force of approximately one third of the maximum load was seen, and the reaction force did not become 0 kN.

Fatigue failure analysis of express freight sliding side covered wagon based on the rigid-flexibility model

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Xiaoxue Liu ◽  
Yahui Zhang ◽  
Suming Xie ◽  
Qiang Zhang ◽  
Hanfei Guo
Keyword(s):  
Fatigue Failure ◽  
Dynamic Stress ◽  
Simulation Analysis ◽  
Fatigue Cracks ◽  
Test Plant ◽  
Body Structure ◽  
Content Type ◽  
Car Body ◽  
Analysis Process ◽  
Model Following

PurposeThe car body stiffness of express freight sliding side covered wagon decreased for the sliding and the resonance vibration based on the flexible car body has affected the dynamics performances. Dynamic loading will cause fatigue cracks and eventually lead to fatigue failure of the car body. This paper aims to investigate the influence of car body flexibility on the evaluation of the failure.Design/methodology/approachIn this paper, the railway vehicles random analysis procedure (RVRAP) is employed to study the fatigue failure of the rigid-flexibility model. Following the analysis process, the rigid-flexibility model is established and four contrastive schemes for simulation analysis are designed. To verify the results, an experimental test using the real car body structure on the vibration test plant is carried out; the RMS of dynamic stress is obtained and compared with the simulation results.FindingsThe results show that the flexibility of the car body has a crucial influence on the fatigue life.Originality/valueThe reliability is verified regarding the use of RVRAP at an appropriate stage on the antifatigue design of the vehicle.

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