Circumferential Residual Stress Research Articles

Effect of Process Parameters on Welding Residual Stress of 316L Stainless Steel Pipe.

316L stainless steel pipes are widely used in the storage and transportation of low-temperature media due to their excellent low-temperature mechanical properties and corrosion resistance. However, due to their low thermal conductivity and large coefficient of linear expansion, they often lead to significant welding residual tensile stress and thermal cracks in the weld seam. This also poses many challenges for their secure and reliable applications. In order to effectively control the crack defects caused by stress concentration near the heat-affected zone of the weld, this paper establishes a thermal elastoplastic three-dimensional finite element (FE) model, constructs a welding heat source, and simulates and studies the influence of process parameters on the residual stress around the pipeline circumference and axial direction in the heat-affected zone. Comparison and verification were conducted using simulation and experimental methods, respectively, proving the rationality of the finite element model establishment. The axial and circumferential residual stress distribution obtained by the simulation method did not have an average deviation of more than 30 MPa from the numerical values obtained by the experimental method. This study also considers the effects of welding energy, welding speed, and welding start position on the pipe's circumferential and axial residual stress laws. The results indicate that changes in welding energy and welding speed have almost no effect on the longitudinal residual stress but have a more significant effect on the transverse residual stress. The maximum transverse residual stress is reached at a welding energy of 1007.4~859.3 J/mm and a welding speed of 6.6 mm/s. Various interlayer arc-striking deflection angles can impact the cyclic phase angle of the transverse residual stress distribution in the seam center, but they do not alter its cyclic pattern. They do influence the amplitude and distribution of the longitudinal residual stress along the circumference. The residual stress distribution on the surface of the pipe fitting is homogenized and improved at 120°.

Research on the Residual Stress Field of a Compression Bushing-Lug Plate in Cold Expansion Strengthening

The accurate acquisition of the residual stress field is the key to clarifying the cold expansion strengthening mechanism of compression bushings, optimizing the extrusion process parameters, and improving the structural fatigue life. In the actual cold expansion strengthening process, the resultant distribution of residual stresses is influenced by the relative extrusion amount, mandrel structure, material properties, and extrusion speed. In this article, the distribution patterns of residual stress after cold extrusion are investigated through a combination of finite element simulation and experimental measurements using a micro-region stress tester. To examine the redistribution law of the stress field of cold expansion reinforcement under external load, the compression bushing-lug-plate-reinforced structure is loaded and unloaded. The results show that large circumferential residual compressive stresses are distributed in the hole wall of the compression bushing after cold expansion. Radial residual stresses are also compressive stresses, although the values are small. In addition, the reinforced structure after cold extrusion presents a large difference in the stress redistribution rules compared with cold extrusion after the load is applied and removed.

Simulation Study on the Influence of a Laser Power Change on the Residual Stress of a Laser-Melting RuT300 Valve Seat

In order to effectively suppress the cracking induced by the excessive residual stress of a laser-melting RuT300 valve seat, the influence of a laser power change on the residual stress was studied by constructing a finite element simulation model of a new power valve seat. The absorption rate of the laser energy on the surface of the material and the change in thermophysical parameters with temperature were taken into account in the model. The results show that the melting and phase-change-hardening areas can be obtained by the laser-melting process. With the increase in laser power, the peak temperature of the molten pool increased almost linearly. The melting zone area and the phase-change-hardening zone depth increased. When the laser power was increased from 2000 to 2600 W, the peak temperature of the laser-melting RuT300 valve seat increased from 2005.09 to 2641.93 °C, the maximum depth of the melting area increased from 0.55 to 0.86 mm, the maximum width of the melting area increased from 3.42 to 4.21 mm, and the maximum depth of the phase-change-hardening area increased from 0.55 to 0.64 mm. The circumferential residual tensile stress in the melting area was much higher than in the radial and axial directions. Along the laser scanning direction, the residual stress in the melting area increased as a whole, and the residual stress in the laser-scanning finishing area greatly increased. With the increase in laser power, the circumferential residual stress at the previous scanning moment decreased, and at the closing moment of the scan, the circumferential residual stress increased with the increase in laser power.

Glycosaminoglycans modulate compressive stiffness and circumferential residual stress in the porcine thoracic aorta

The mechanical properties of the aorta are influenced by the extracellular matrix, a network mainly comprised of fibers and glycosaminoglycans (GAG). In this work, we demonstrate that GAG contribute to the opening angle (a marker of circumferential residual stresses) in intact and glycated aortic tissue. Enzymatic GAG depletion was associated with a decrease in the opening angle, by approximately 25% (p = 0.009) in the ascending (AS) region, 32% (p = 0.003) in the aortic arch (AR), and 42% (p = 0.001) in the lower descending thoracic (LDT) region. A similar effect of GAG depletion on aortic ring opening angle was also observed in previously glycated tissues. Using indentation testing, we found that the radial compressive stiffness significantly increased in the AS region following GAG depletion, compared to fresh (p = 0.006) and control samples (p = 0.021), and that the compressive properties are heterogeneous along the aortic tree. A small loss of water content was also detected after GAG depletion, which was most prominent under hypotonic conditions. Finally, the AS region was also associated with a significant loss of compressive deformation (circumferential stretch that is < 1) in the inner layer of the aorta following GAG depletion, suggesting that GAG interact with ECM fibers in their effect on aortic mechanics. The importance of this work lies in its identification of the role of GAG in modulating the mechanical properties of the aorta, namely the circumferential residual stresses and the radial compressive stiffness, as well as contributing to the swelling state and the level of circumferential prestretch in the tissue. Statement of significanceThe mechanical properties of the aorta are influenced by the composition and organization of its extracellular matrix (ECM) and are highly relevant to medical conditions affecting the structural integrity of the aorta. The extent of contribution of glycosaminoglycans (GAG), a relatively minor ECM component, to the mechanical properties of the aorta, remains poorly characterized. This works shows that GAG contribute on average 30% to the opening angle (an indicator of circumferential residual stresses) of porcine aortas, and that GAG-depletion is associated with an increased radial compressive stiffness of the aorta. GAG-depletion was also associated with a loss of water content and compressive deformation in the inner layers of the aortic wall providing insight into potential mechanisms for their biomechanical role.

Interstitial flow, pressure and residual stress in the aging carotid artery model in FEBio.

Vascular smooth muscle cells (VSMCs) are subject to interstitial flow-induced shear stress, which is a critical parameter in cardiovascular disease progression. Transmural pressure loading and residual stresses alter the hydraulic conductivity of the arterial layers and modulate the interstitial fluid flux through the arterial wall. In this paper, a biphasic multilayer model of a common carotid artery (CCA) with anisotropic fiber-reinforced soft tissue and strain-dependent permeability is developed in FEBio software. After the verification of the numerical predictions, age-related arterial thickening and stiffening effects on arterial deformation and interstitial flow are computed under physiological geometry and physical parameters. We found that circumferential residual stress shifts outward in each layer and its gradient increases up to 6 times with aging. Internally pressurized CCA displays nonlinear deformation. In the aged artery, the circumferential stress becomes greater on the media layer (82-158kPa) and lower on the intima and adventitia (19-23kPa and 25-28kPa, respectively). The radial compression of the intima reduces the total hydraulic conductivity by 48% in the young and 16% in the aged arterial walls. Consequently, the average radial interstitial flux increases with pressure by 14% in the young and 91% in the aged arteries. Accordingly, the flow shear stress experienced by the VSMCs becomes more significant for aged arteries, which may accelerate cardiovascular disease progression compared to young arteries.

Simulation Research on Residual Stress of Swage Autofrettage-processed High-Pressure Cylinder

The vital component of the high-pressure pump is the high-pressure cylinder, which undergoes pulsating cyclic loads during operation. This exposure can lead to fatigue cracking and limit the pump’s overall performance. To address this issue, a swage autofrettage treatment method for the high-pressure cylinder is proposed based on the principles of autofrettage technology. The structure parameters of the mandrel are designed to optimize its role in the treatment process. Subsequently, a swage autofrettage simulation model is established, considering the Bauschinger effect to analyze the distribution of residual stress about the mandrel interference percentage. The results demonstrate that the swage autofrettage treatment improves the stress distribution in the high-pressure cylinder, causing the inner wall surface to undergo a circumferential residual compressive stress. Within a specific range, the Bauschinger effect becomes more significant as the mandrel interference percentage increases. This study provides insights for enhancing the durability and performance of high-pressure cylinders while adhering to mechanical engineering standards.

Analysis of the geometrical influence of ring-opening samples on arterial circumferential residual stress reconstruction.

This work consists of analyzing the impact of geometrical features (thickness and curvature) on the estimation of circumferential residual stresses in arteries. For this purpose, a specific sample of lamb abdominal artery is chosen for analysis and, through computational tools based on Python libraries, the stress-free geometry is captured after the ring opening test. Numerical simulations are then used to reconstruct the sample in order to estimate the circumferential residual stresses. Then, four stress-free geometry models are analyzed: an ideal geometry, i.e., constant curvature and thickness; a constant curvature and variable thickness geometry; a variable curvature and constant thickness geometry; and a variable curvature and thickness geometry. The numerical results show that models perform well from a geometric point of view, where the most different feature was the closed outer perimeter that differs about 14% from the closed real sample. As far as residual stress is concerned, differences up to 198% were found in more realistic models taking a constant curvature and thickness model as reference. Thus, the analysis of a realistic geometry with highly variable curvature and thickness can introduce, compared to an idealized geometry, significant differences in the estimation of residual stresses. This could indicate that the characterization of arterial residual stresses is not sufficient when considering only the opening angle and, therefore, it is also necessary to incorporate more geometrical variables.

The Residual Stress Control of Thin-walled Sleeve Parts with Weak Rigidity

Photoelectric products in the military industry tend to be lightweight in design, requiring the part to be lightweight and have high specific strength. As one of the structural parts of photoelectric products, the thin-walled sleeve part has the peculiarity of lightweight and thin wall thickness. Nevertheless, the residual stress during machining processing poses an adverse effect on the accuracy of the parts. In this paper, the influence of residual stress on the accuracy of the parts during the processing was studied. Before fine machining, the residual stress was reduced by artificial aging techniques and ultrasonic beam control methods. Finally, the effect of the two stress relief methods was evaluated according to the qualified rate of the processing accuracy of the parts. The research results show that the axial residual stress of the part is larger than the circumferential residual stress. Both artificial aging techniques and ultrasonic beam control can eliminate residual stress, and the ultrasonic beam control method is more targeted and uniform.

Study on the Residual Stress Distribution of Bi-Directional Cold Expansion Process Performed on Open Holes

AbstractTraditional unidirectional cold expansion technology usually generates non-uniform distribution of residual stress in the thickness direction of holes, which is harmful to the improvement of fatigue life of holes. The present work proposed a bi-directional cold expansion procedure to realize the homogenization of residual stress in the thickness direction of the cold expanded hole, thereby further improved antifatigue performance of cold expanded hole. For this aim, a series of finite element (FE) simulations were carried out to investigate the effectiveness of the bi-directional cold expansion procedure and optimize the process parameters. The results showed that the optimized bi-directional cold expansion process generated a more uniform distribution of residual circumferential compressive stress in the thickness direction comparing to the simplified bidirectional cold expansion process using a single mandrel. For the Aluminum alloy 7050-T7451, when the first interference level I1 = 1.8%, the largest and the most uniform residual circumferential compressive stress was achieved, which suggested the best anti-fatigue performance.

Effect of cryogenic machining-strengthening process on enhanced surface integrity and fatigue properties of ZK61M magnesium alloy

Excessive heat and fatigue are important factors affecting the machinability and service performance of magnesium alloy. Cryogenic processing is an effective method to reduce the temperature of the tool and the component, thus improving the machinability of magnesium alloys. The fatigue of workpieces is affected by machining and strengthening processes. However, the current studies on cryogenic processing hardly comprehensively consider the effect of cutting and rolling. To investigate the effect of cryogenic air and pre-cutting processes on rolling, the sequential cutting and rolling experiments were conducted on ZK61M magnesium alloy under dry and two cryogenic cooling conditions. Effects of coolant during sequential machining and rolling processes on forces, surface roughness, microstructure, hardness and residual stresses were investigated. The fatigue properties of ZK61M in the cryogenic processes were also studied. The results show that the rolling force is affected by the coolant lubrication and the surface hardening generated by the previous process. Cryogenic rolling can effectively reduce the surface roughness, increase the circumferential residual compressive stress and reduce the axial residual compressive stress. The feed force of the dry turning followed by rolling with liquid nitrogen (ST + NR) process is the smallest, which is 136.4 N. And the surface roughness (Ra) is also the smallest, which is 0.42 μm, 46.8 % lower than the traditional process. Meanwhile, the ST + NR process can prolong the fatigue life of ZK61M magnesium alloy by 62.9 % compared with conventional process. Moreover, the surface roughness and residual stress have significant influences on fatigue life of ZK61M magnesium alloy, followed by the depth of work hardening layer, and finally the surface hardness. Cryogenic cutting and strengthening process can effectively suppress the initiation and propagation of fatigue cracks.

Finite Element Analysis of Split Sleeve Cold Expansion Process on Multiple Hole Aluminum Alloy.

Multiple cold expansion holes are widely used in connection areas of aircraft structures, in order to achieve uniform load transfer of the skin or connection parts. Split sleeve cold expansion (SSCE) is widely used to enhance the fatigue life of fastener holes by applying compressive residual stresses around the holes. In this study, the finite element method (FEM) was used to research the distribution and variation of residual stresses along the hole edges of 7075AA single-hole and multi-hole cold expansion (CE) specimens. Full-field strain measurements of single-hole and multi-hole specimens were performed using two-dimensional digital image correlation (DIC), and the residual stress and strain at the hole edge of the specimens measured by FEM and DIC were compared. FEM results shows that the maximum circumferential and radial residual stresses of three-hole specimens with three-hole spacing are increased by 5.37% and 31.53% compared with single-hole specimens. The maximum circumferential residual stress of three-hole specimens with four-hole spacing increases by 7.25% compared with a single hole, but the radial residual stress decreases by 12.98%. In addition, for three-hole specimens with hole spacing three times the hole diameter, the strengthening effect of SSCE in the order of middle hole, then left hole, and, finally, right hole is better than that of SSCE in the order of left to right hole. FEM and DIC full-field strain results are basically consistent.

Investigating the influence of the superfinishing process on the residual stress of the raceway

The residual stress of bearing inner race after superfinishing machining along the axial direction is usually measured by using an X-ray analyzer. The experimental results show that the residual stress on the surface of the bearing raceway is compressive stress with an average value of −266 to −438 MPa, and the circumferential residual stress on the bottom surface of the bearing raceway is greater than the axial residual stress. The obtained results reveal that the oilstone pressure has a significant effect on the residual compressive stress. It is found that increasing the oilstone pressure can significantly improve the residual compressive stress on the surface of the bearing raceway.

EFFECT OF GLYCOSAMINOGLYCANS ON OPENING ANGLE OF INTACT &amp; CROSSLINKED AORTAS

EFFECT OF GLYCOSAMINOGLYCANS ON OPENING ANGLE OF INTACT &amp; CROSSLINKED AORTAS

Research on Fatigue Life Prediction Model of Combined Sleeve

For the purpose of solving the problem of fatigue design of sleeve in plunger pump, a model of life prediction of combined sleeve using fatigue damage parameters as driving force is proposed in this paper. The circumferential residual stress after assembling and the circumferential stress after loading are calculated. The new model is used to calculate the life of the combined sleeve based on SWT method, and the correctness and rationality of the model are verified by the finite element method. The results show that the fatigue life of the combined sleeve is much longer than that of the integrated sleeve, and the interference has final effect on the fatigue life of the combined sleeve.

Control of Welding Residual Stress in Large Storage Tank by Finite Element Method

T-joint welding is a key manufacturing process of large storage tanks. However, complex residual stresses are generated and have a great effect on the structural integrity of storage tanks. The high residual stress caused by welding and the discontinuous structure may result in tank cracking and failure. In this work, the residual stress distributions on the inner surface, outer surface, and thickness direction of the T-joint were investigated by using the finite element method and indentation test method. The effect of local PWHT with different heating temperatures, heating rates, and heating widths on the residual stress distribution was also discussed. Results show that the residual stress of the T-shaped joint is high due to the serious structure discontinuity, multi-layer welding, and high strength. Among all the stresses, the circumferential residual stress is the highest and most concentrated in the outer weld connected with the annular plate. The residual stress gradually decreases with the increase in the heat treatment temperature. When the heating rate is less than 106 °C/h, the residual stress gradually decreases with the decrease in the heating rate. The large thermal deformation caused by heat treatment can be simultaneously avoided by heating the inside and outside of the T-joint. The residual stress decreases with the decrease in the width of the heating zone. The residual stress can be regulated by using a smaller width in the heating zone. An optimized heat treatment scheme with a heating temperature of 700 °C, heating rate of 56 °C/h, and heating width of 200 mm was proposed, which has a good ability to control residual stresses and improve the quality of the T-joint. It also has a good application in engineering.

Bifurcation analysis of residually stressed neo-Hookean and Ogden electroelastic tubes.

The conditions for bifurcation of a circular cylindrical tube of elastic material subjected to combined axial loading and internal pressure are well known and are frequently used as a reference in related works. The present paper takes the theory further by considering a residually stressed circular cylindrical dielectric tube subjected to a combination of internal or external pressure, axial load and radial electric field. We examine axisymmetric incremental deformations and increments in the electric displacement superimposed on a known finitely deformed and residually stressed configuration in the presence of an electric field. The governing equations and boundary conditions are first obtained in general form and then specialized for the neo-Hookean and Ogden electroelastic models. The system of equations is solved numerically for different values of charge density and radial and circumferential residual stresses, and the results are compared with the purely elastic case. The bifurcation curves are presented as the azimuthal stretch on the inner surface versus the axial stretch together with the corresponding zero pressure curves. This article is part of the theme issue 'The Ogden model of rubber mechanics: Fifty years of impact on nonlinear elasticity'.

Optimization of machining parameters applied in hard turning of large components for cooling lubrication methods

The increasing demands concerning renewable energy have required ever-bigger projects, as seen with wind turbine cases; in these large projects, the surface contact presents high load and wear resistance requirements. The cooling and lubrication methods in machining are highlighted due to the reduction of costs and environmental impacts. In functional hardened surfaces, it is critical to understand the integrity aspects once they significantly affect the durability of the component. This work clarifies, how the machining parameters of feed, depth of cut, velocity of cut, minimum quantity of lubrication, and abundant cooling affected the machined surface in a large component, with a discussion about microstructural altered layer, residual stresses, and Sa, Sq, and Sz statistical parameters. The results indicated that the minimum quantity lubrication and abundant cooling produced highly compressive circumferential residual stresses. Both methods produced surfaces free of significant microstructure altered layers. The altered surface layer was very thin when detected, with a thickness of up to 2.35 µm. On optimal conditions, the minimum quantity lubrication, in relation to abundant cooling, presented residual stresses 37% higher, a thickness of altered layer 74% lower, and Sa and Sz roughness, respectively, 47% and 11% lower and Sz 12% higher.

Orientation and Residual Stress Distributions in Thick Melt Spun Polystyrene and Polycarbonate Filaments

Abstract A study of orientation development and residual stresses in thick melt spun polystyrene filaments and polycarbonate filaments described. Linear relationships between spinline stress and mean birefringence under different melt spinning conditions were obtained. These results were used together with models of the dynamics of melt spinning to predict the characteristics of thick melt spun filaments. Birefringence distrbutions and residual stresses were computed. High orientations and compressive circumferential residual stresses were predicted at the larger radii and low orientation and tensile circumferential and radial residual stress in the fiber core are obtained. The distribution of birefringence across the thickness of thick melt spun filaments was measured by determining changes of retardation across a wedge. The birefringence distributions were correlated with severity of quench and model prediction. Thick melt spun fibers were peeled and found to have fibrillar cores.

A biodegradable magnesium alloy vascular stent structure: Design, optimisation and evaluation

The existing biodegradable magnesium alloy stent (BMgS) structure is prone to problems, such as insufficient support capacity and early fracture at areas of concentrated stress. Herein, a stent structural design, which reduced the cross section of the traditional sin-wave stent by nearly 30% and introduces a regular arc structure in the middle of the support ring. The influence of the dual-parameter design of bending radius (r) and ring length (L) on plastic deformation, expansion and compression resistance performances are discussed. The non-dominated sorting genetic algorithm II (NSGA-II) was used to search for the optimal solution. It was found that the introduction of parameter r effectively improved the plastic deformation and expansion performance, and the reduction of L improved stent compression resistance. Finally, an optimized stent configuration was obtained. In vitro mechanical tests, including balloon inflation, radial strength and flexibility, verified the simulation results. The radial strength for the optimised stent increases by approximately 40% compared with that for the sinusoidal stent. Microarea X-ray diffraction result shows that the circumferential residual stress for the optimised stent decreases by half compared with that for the sinusoidal stent, thus effectively reducing the stress concentration phenomenon. Statement of significanceDespite current progress in BMgS research, the optimal design of the structure is limited. We present a new type of structurally designed stent. The performance of this stent was analysed by a finite element method and experimentally verified. The structural design positively influenced stent performance.

Intramural Distributions of GAGs and Collagen vs. Opening Angle of the Intact Porcine Aortic Wall.

The heterogeneity and contribution of collagen and elastin to residual stresses have been thoroughly studied, but more recently, glycosaminoglycans (GAGs) also emerged as potential regulators. In this study, the opening angle of aortic rings (an indicator of circumferential residual stresses) and the mural distributions of sulfated GAGs (sGAG), collagen, and elastin were quantified in the ascending, aortic arch and descending thoracic regions of 5- to 6-month-old pigs. The opening angle correlated positively with the aortic ring's mean radius and thickness, with good and moderate correlations respectively. The correlations between the sGAG, collagen, elastin, and collagen:sGAG ratio and the opening angle were evaluated to identify aortic compositional factors that could play roles in regulating circumferential residual stresses. The total collagen:sGAG ratio displayed the strongest correlation with the opening angle (r = -0.715, p < 0.001), followed by the total sGAG content which demonstrated a good correlation (r = 0.623, p < 0.001). Additionally, the intramural gradients of collagen, sGAG and collagen:sGAG correlated moderately with the opening angle. We propose that, in addition to the individual role sGAG play through their content and intramural gradient, the interaction between collagen and sGAG should be considered when evaluating circumferential residual stresses in the aorta.