Fatigue failure of 45# steel in dry sliding against Kevlar/PTFE hybrid composite under elevated load

2017 ◽  
Vol 232 (4) ◽  
pp. 391-400
Author(s):  
Bingli Fan ◽  
Yulin Yang ◽  
Shicheng Yan ◽  
Jian Ma ◽  
Dapeng Gu ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Cross Section ◽  
Fatigue Failure ◽  
Hybrid Composite ◽  
Friction Pair ◽  
Fatigue Cracks ◽  
Wear Characteristics ◽  
Opposite Case ◽  
Fabric Composite ◽  
Final Failure

Frictional failure is inevitable for friction pairs. A common sense about the frictional failure of steel-polymer composite friction pair is that the polymer composites are the primary failure part rather than the steel counterpart. However, an opposite case was newly found in the case of fabric self-lubricating liner (Kevlar/PTFE hybrid composite) spherical plain-bearing under elevated load: the steel counterbody suffered a fatigue failure before the fabric composite fails, which resulted in the final failure of the bearing. This paper investigated such fatigue failure of surface chrome plated 45# steel by systematically studying the wear characteristics of 45# steel and fabric composite, the stress distribution of the 45# steel and fatigue features within cross section of the 45# steel. Results showed that wear characteristics of both fabric composite and 45# steel exhibited regional characters. Failure mechanism of the 45# steel was found to be fatigue failure (mainly fatigue pitting), which was revealed by mathematical analysis of the stress distribution of the 45# steel and the fatigue cracks found within subsurface of the cross section of the 45# steel.

Residual stress distribution in built-in beams

2020 ◽  
pp. 146442072095861
Author(s):  
FA de Castro ◽  
Paulo P Kenedi ◽  
LL Vignoli ◽  
I I T Riagusoff
Keyword(s):  
Residual Stress ◽  
Finite Element ◽  
Stress Distribution ◽  
Cross Section ◽  
Cross Sections ◽  
Element Model ◽  
Residual Stress Distribution ◽  
Concentrated Load ◽  
Load Growth ◽  
Final Failure

Metallic hyperstatic structures, like beams, submitted to excessive loads, do not fail completely before fully yielding in more than one cross section. Indeed, for built-in beams, three cross sections must be fully yielded before the final failure can occur. So, modeling the evolution of the cross-section residual stress distribution is an important subject that should be addressed to guarantee the stress analysis modeling correctness. This paper analyses the residual stress distribution evolution, in critical cross sections, of built-in beams during a transversal concentrated load growth, until the final failure through hinges formation. A finite element model is also presented. The results show good matches with the numerical model, used as a reference.

Before Calculating the Teeth of Spur gears on the Bend

2020 ◽  
pp. 151-158
Author(s):  
Yurii Nevdakha ◽  
◽  
Viktor Dubovyk ◽  
Nataliia Nevdakha ◽  
Fedir Zlatopolskiy ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Cross Section ◽  
Bending Strength ◽  
Fatigue Cracks ◽  
Local Stress ◽  
Transition Curve ◽  
Variable Cross ◽  
The Real ◽  
Calculated Dependence ◽  
Number Of Teeth

The aim of the work is to improve the calculations of spur cylindrical wheels per bend, due to the fact that the existing formulas do not give the actual value of the maximum stress, and the diagram does not correspond to the real law of stress distribution. In order to obtain satisfactory results, it is more correct to calculate the teeth at the maximum local stress. Combining the coefficients and substantiating the calculated dependence to determine the value of the coefficient of the shape of the tooth under load, applied at any point of the working profile of the tooth, to obtain formulas for the bending strength of the teeth of the gear and wheel. When calculating the bending teeth, the calculation is based on the stresses arising at the base of the tooth, under the load applied at the top of the tooth. Consider first the most common calculation scheme. Dangerous section of the tooth as seen from the plot of total stresses indicates that the maximum normal stress occurs on the non-working side of the tooth - the compression side, however, since fatigue cracks occur at the base of the tooth on the stretching side, the calculation is based on tensile stress on the working side. The hypothesis of non-curvature of flat sections is unfair for short beams of variable cross section, so the total diagram does not correspond to the real law of stress distribution. But at the base of the tooth near the transition curve is the place of stress concentration. The actual dangerous cross-section lies below the cross-section of the depression, this is confirmed by the fact that the fatigue cracks form an angle with the load curve close to straight, and the fracture of the tooth has a convex shape. In this case, it is more correct to calculate the teeth at the maximum local stress. Combining the coefficients obtained a calculated dependence to determine the value of the coefficient of the shape of the tooth under load, applied at any point of the working profile of the tooth. As a result of the study it was found that the coefficient of tooth shape decreases with increasing number of teeth. This result was expected because as the number of teeth increases, the angle between the teeth decreases, and neighboring teeth perceive part of the stress that occurs in the loaded tooth. The formulas for checking the bending strength of gear teeth and wheels are obtained. The above refinement calculations of the teeth on the bend reflect the beneficial effect of improving the accuracy of the manufacture of teeth.

scholarly journals STRESS DISTRIBUTION IN CROSS-SECTION OF RC COLUMN

2009 ◽  
Vol 74 (637) ◽  
pp. 425-431
Author(s):  
Ippei MARUYAMA ◽  
Masahiro SUZUKI ◽  
Masaomi TESHIGAWARA ◽  
Ryoichi SATO
Keyword(s):  
Stress Distribution ◽  
Cross Section ◽  
Rc Column

Stress Distribution in a Uniformly Rotating Equilateral Triangular Shaft

1955 ◽  
Vol 22 (2) ◽  
pp. 255-259
Author(s):  
H. T. Johnson
Keyword(s):  
Approximate Solution ◽  
Stress Distribution ◽  
Boundary Conditions ◽  
Plane Strain ◽  
Cross Section ◽  
Plane Stress ◽  
Biharmonic Equation ◽  
Approximate Solutions ◽  
Distribution Of Stresses ◽  
General Method

Abstract An approximate solution for the distribution of stresses in a rotating prismatic shaft, of triangular cross section, is presented in this paper. A general method is employed which may be applied in obtaining approximate solutions for the stress distribution for rotating prismatic shapes, for the cases of either generalized plane stress or plane strain. Polynomials are used which exactly satisfy the biharmonic equation and the symmetry conditions, and which approximately satisfy the boundary conditions.

scholarly journals Assessment of Rectangular Cavity in Concrete Gravity Retaining Wall using Finite Element Method

2019 ◽  
Vol 8 (4) ◽  
pp. 2656-2661
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Distribution ◽  
Cross Section ◽  
Retaining Wall ◽  
Rectangular Cavity ◽  
Gravity Retaining Wall ◽  
The Cross ◽  
Conditions Of Stability ◽  
Element Method

The design of the Gravity retaining wall (GRW) is a trial and error process. Prevailing conditions of backfill are used to determine the profile of GRW, which proceeds with the selection of provisional dimensions. The optimum section is having factors of safety of stability higher than the allowable values and stresses in the cross-section smaller than permissible. The cross-section is designed to fulfill conditions of stability, subjected to very low stresses. The strength of the material, which is provided in the cross-section remains unutilized. A computer program is developed to find stresses at various locations on the cross-section of GRW using the Finite Element Method (FEM). A discontinuity in the form of a rectangular cavity is introduced in the cross-section of GRW to optimize it. The rectangular cavity is introduced in the cross-section of GRW at different locations. An attempt is made in this paper to find the stress distribution in the gravity retaining wall cross-section and to study the effect of the rectangular cavity on the stress distribution. Two cases representing different locations are considered to study the effect of the cavity. The location of the cavity is distinguished by the parameter w, the effects of cases with varied was 0.2305 (Case-I) and 0.1385 (Case-II) are observed. The cavity, which is provided not only makes the wall structurally efficient but also economically feasible.

Ballistic Performance Evaluation of Kevlar-Glass Fibre Hybrid Composite Laminate against Medium Velocity Impact

2021 ◽  
Vol 1165 ◽  
pp. 47-64
Author(s):  
Saurabh S. Kumar ◽  
Rajesh G. Babu ◽  
U. Magarajan
Keyword(s):  
Energy Absorption ◽  
Specific Energy ◽  
Glass Fibre ◽  
Hybrid Composite ◽  
Composite Laminates ◽  
Areal Density ◽  
Ballistic Performance ◽  
Performance Requirement ◽  
Specific Energy Absorption ◽  
Fabric Composite

In this paper, the post ballistic impact behaviour of kevlar-glass fibre hybrid composite laminates was investigated against 9×19 mm projectile. Eight different types of composite laminates with different ratios of kevlar woven fibre to glass fibre were fabricated using hand lay-up with epoxy matrix. Ballistic behaviour like ballistic Limit (V50), energy absorption, specific energy absorption and Back Face Signature (BFS) were studied after bullet impact. The results indicated that as the Percentage of glass fibre is increased there was a linear increment in the ballistic behaviour. Addition of 16% kevlar fabric, composite sample meets the performance requirement of NIJ0101.06 Level III-A. Since the maximum specific energy absorption was observed in Pure Kevlar samples and the adding of glass fibre increases the weight and Areal Density of the sample, further investigations need to be carried out to utilize the potential of glass fibre for ballistic applications.

Two body abrasive wear characteristics of Al7068/Si3N4/BN hybrid composite

2019 ◽  
Vol 6 (6) ◽  
pp. 066502
Author(s):  
S Kumar ◽  
M Sakthivel ◽  
S Sudhagar ◽  
K Nivethan
Keyword(s):  
Abrasive Wear ◽  
Hybrid Composite ◽  
Wear Characteristics

P5631The impact of plaque type on strut embedment/protrusion and shear stress distribution in bioresorbable scaffold

2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
E Tenekecioglu ◽  
R Torii ◽  
Y Katagiri ◽  
J Dijkstra ◽  
R Modolo ◽  
...  
Keyword(s):  
Shear Stress ◽  
Stress Distribution ◽  
Cross Section ◽  
Vessel Wall ◽  
Shear Stress Distribution ◽  
Local Flow ◽  
Bioresorbable Scaffold ◽  
Plaque Type ◽  
The Impact ◽  
Section Level

Abstract Background and aim Scaffold design and plaque characteristics influence implantation outcomes and local flow dynamics in treated coronary segments. Our aim is to assess the impact of strut embedment/protrusion of bioresorbable scaffold on local shear stress distribution in different atherosclerotic plaque types. Method Fifteen Absorb everolimus-eluting Bioresorbable Vascular Scaffolds were implanted in human epicardial coronary arteries. Optical coherence tomography (OCT) was performed post-scaffold implantation and strut embedment/protrusion were analyzed using a dedicated software. OCT data was fused with angiography to reconstruct three-dimensional coronary anatomy. Blood flow simulation was performed and wall shear stress (WSS) was estimated in each scaffolded surface and the relationship between strut embedment/protrusion and WSS was evaluated. Results There were 9083 struts analysed. Ninety-seven percent of the struts (n=8840) were well apposed and 243 (3%) were malapposed. At cross-section level (n=1289), strut embedment was significantly increased in fibroatheromatous plaques (76±48μm) and decreased in fibro-calcific plaques (35±52 μm). Compatible with strut embedment, WSS was significantly higher in lipid-rich fibroatheromatous plaques (1.50±0.81Pa), whereas significantly decreased in fibro-calcified plaques (1.05±0.91Pa). After categorization of WSS as low (<1.0 Pa) and normal/high WSS (≥1.0 Pa), the percent of low-WSS in the plaque subgroups were 30.1%, 31.1%, 25.4% and 36.2% for non-diseased vessel wall, fibrous plaque, fibro-atheromatous plaque and fibro-calcific plaque, respectively (p-overall<0.001). Table 1. Cross-section level Embedment/Protrusion and WSS according to the plaque type Plaque type Embedment depth (μm) Protrusion distance (μm) WSS (Pa) Non-atherosclerotic intimal thickening/normal vessel wall (n=2275) 47±34*Δ¥ 123±34¶Ξπ 1.44±0.9解 Fibrous (n=4191) 53±40*#& 118±38¶Ψ‡ 1.24±0.78αθ∞ Fibroatheromatous (n=2027) 76±48#ΦΔ 94.6±46Ω†Ψπ 1.50±0.81Σ§α Fibro-calcific (n=590) 35±52&Φ¥ 139±50‡†Ξ 1.05±0.91∞£Σ For embedment: *p=0.09, #p<0.001, &p<0.001, Φp<0.0001, Δp<0.0001, ¥p<0.0001. For protrusion: ¶p=0.74, Ξp<0.0001, πp<0.0001, Ψp<0.0001, ‡p<0.0001, †p<0.0001. For WSS: θp<0.001, §p=0.06, £p<0.0001, αp<0.0001, ∞p<0.0001, Ωp<0.0001. n=total strut number in each plaque type, p-values come from mixed-effects regression analysis. Conclusion The composition of the underlying plaque influences strut embedment which seems to have effect on WSS. The struts deeply embedded in lipid-rich fibroatheromas plaques resulted in higher WSS compared to the other plaque types.

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.

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