Effect Of Residual Stress Research Articles

On-machine measurement method of hole parallelism error based on multi-sensor fusion

The hole parallelism error (HPE) is one of the key quality parameters for mechanical parts. However, HPE can usually be out-of-tolerance due to the coupling effect of residual stress, cutting stress, and geometric structure during its machining process. Thus, on-machine measurement and timely adjustment are important guarantees for HPE. This paper proposes an on-machine measurement method of HPE based on multi-sensor fusion that is low-cost, efficient, and suitable for mass production of parts. First, the axis of the cylindrical surface is directly extracted using five points according to the spatial line position relation. Then, the mathematical model of the HPE of two holes’ axes was established through the theory of spatial analytic geometry. The HPE is characterized using two parameters: parallelism magnitude and parallelism direction. Finally, the feasibility of the measurement method in principle and practical application is verified by simulation and experiment. The simulation tests show that the maximum value of the relative error of parallelism magnitude and parallelism direction is −1.38‱. The actual experiments show that the relative error of the measurement results compared with the coordinate measuring machine is 6.23%. None of the standard deviations exceeds the order of magnitude of 0.01 mm. The difference in measurement uncertainty is 0.0003 mm.

A novel formula for predicting the ultimate compressive strength of the cylindrically curved plates

"The present study aims to develop an empirical formula to predict the ultimate compressive strength of unstiffened cylindrically curved plates. Drawing from an extensive analysis of 400 unique curved plate scenarios under longitudinal compression, we investigated critical parameters: the flank angle (denoted as θ), plate aspect ratio (denoted as a/b), and plate slenderness ratio (denoted as β). The ANSYS Nonlinear Finite Element Method (NLFEM) was employed to assess each scenario, considering the average level of initial imperfections (denoted as 0.1β2t) and configurations of one-bay and one-span. It is important to note that the models were designed without accounting for the effects of residual stresses. The simulation data generated from this analysis served as the foundation for developing our empirical formula. The proposed formula strongly agreed with the numerical simulations and experimental test results. This research provides structural engineers with a reliable predictive tool, aiding in more accurate predictions of the ultimate limit state (ULS) of curved plates during early design phases.

Residual stress and thickness effects on fracture behavior of trilayer films during uniaxial loading

The effects of residual stress and film thickness on crack evolution in metallic trilayers deposited on polyimide substrate have been investigated during uniaxial tensile loading. Four different systems, consisting of Mo/Cu/Cr layers deposited on polyimide, with nominal thicknesses of 100/100/100 or 100/500/100 nm, were developed using two physical vapor deposition techniques, resulting in opposite as-deposited high residual stress for the top Cr layer (about +2.7 GPa versus -2.6 GPa). First, it was found that the higher the compressive residual stress of the top Cr layer and the thickness of the middle Cu layer, the higher the critical strain to initiate crack propagation in the trilayer film system. Second, it was found that the higher the compressive residual stress of the top Cr layer and the thickness of the middle Cu layer, the lower the maximum crack density in the trilayers. The maximum crack density in the thicker system with Cr in a tensile residual stress was similar to the maximum crack density in the thinner system with the Cr top layer in a compressive residual stress.

Modeling the effect of microscale residual stresses on acoustoelasticity for carbon fiber composites

Modeling the effect of microscale residual stresses on acoustoelasticity for carbon fiber composites

Equivalent single layer approach for ultimate strength analysis of box girder under bending load

The objective of this study is to assess the ultimate strength of box girder using equivalent single layer (ESL) approach. Box girders, composed of stiffened panels, are subjected to a four-point bending load for the ultimate strength analysis. The results of ESL were validated using FEM and experiments. Modeling of ESL includes a single plate with the same stiffness as the actual stiffened panel topology, as opposed to traditional FEM modeling and test specimen, where the stiffener is explicitly modeled. For ESL approach, VUGENS subroutine in Abaqus software is used to define the non-linear stiffness properties. Material and geometric non-linearities were considered during simulations. The ESL stiffness matrix was derived from unit cell simulations under six loading conditions. In this case, a unit cell is a periodic structure that represents the entire stiffened panel model. Contact interaction is utilized to simulate the controlled movement of a hollow cylinder contacting a box girder, a precise modeling approach essential for comprehensive analysis. The explicit dynamic analysis is used to allow the large deformation and non-linear material behavior on stiffened panels. The effect of initial imperfection, residual stress, and stiffener slenderness on the ultimate strength was studied. The ultimate strength of a box girder is determined by its maximum bending moment. According to the results, the ESL model achieves results similar to the traditional FEM model and experiment. The accuracy of ESL to FEM in the ultimate strength assessment varies depending on the magnitude of residual stress and initial imperfection applied to the stiffened panel.

Elastic and inelastic major-axis flexural buckling of cellular steel columns

This study investigates the elastic and inelastic major-axis flexural buckling of cellular steel columns. Based on the stationary principle of potential energy, the existing elastic buckling load equation is refined to incorporate the local bending deformations at web posts. The column strength curve for determining the critical loads is then derived. For the elastic buckling, the refinement provides a significant improvement. For the inelastic buckling, the effects of residual stresses and initial geometric imperfections on the column strength are examined by the validated nonlinear finite element (FE) models. The initial geometric imperfection amplitudes of L/300 and L/500, where L is the column length, are recommended for global buckling of cellular steel columns fabricated from the parent steel shapes with h/b ≤ 1.2 and h/b > 1.2, respectively, where h/b is the depth-to-width ratio of the parent steel shapes. The developed column strength curve conservatively predicts the major-axis flexural buckling strength of practical cellular steel shapes, with an average prediction-to-FE buckling stress ratio of 0.97. A comparison also shows that the current EC3 and AISC360 equations are applicable for predicting the strength of practical cellular columns, provided that the refined elastic buckling load is adopted.

Residual stress effect on fatigue behavior of steel welded: A review

A manufacturing process that can be used to join two or more steels by welding. This process involves an uneven distribution of heat which causes residual stresses to occur. Residual stresses in the material, even though the external forces acting have been removed in the local heat distribution area in plastic deformation. Residual stress has a significant relationship with material exhaustion. Tensile residual stress (TRS) can reduce fatigue life, while compressive residual stress (CRS) will increase fatigue life. CRS makes the stress received by the material lower, resulting in a more expansive Fatigue Crack Propagation (FCP) area and a much smaller final fracture cross-section. Materials with CRS have a higher fatigue life than materials without CRS. Fatigue resistance can be increased by reducing the residual stress in tension. Currently one method that is widely used to increase fatigue resistance is shot peening. Shot peening provides CRS on the surface so that crack initiation originates below the surface of the material causing an increase in fatigue resistance.

Experimental investigation on the cold-forming effect of high strength cold-formed steel sections

Many researches were carried out on the cold-forming effect of cold-formed steel sections while research on that of high strength cold-formed steel sections was quite few. Thus, an experimental investigation on the material property and residual stress of high strength cold-formed steel sections was carried out and the effect of residual stress on the overall stability bearing capacity was studied. It was found that: (1) the increase of yield strength of high strength cold-formed steel was similar to that of Q235 and Q345 cold-formed steel; (2) the residual stress at corner parts was much higher than that at flat parts and the bending residual stress of high strength cold-formed steel was much lower than that of Q235 and Q345 cold-formed steel; (3) residual stress would lead to a decline of the overall stability bearing capacity of axially loaded high strength cold-formed C-shaped steel sections and the effect became lower with the increase of strength grade.

A novel study on microstructure and crystallographic characteristics of Cu-Cr-Zr alloy manufactured by laser powder bed fusion

This work systematically investigated and discussed the differences in microstructure and crystallographic characteristics between the horizontal and vertical directions of the Cu-Cr-Zr alloy prepared by laser powder bed fusion (LPBF) and analyzed the formation mechanism of the subgrains. A sample with a relative density close to full density (99.63 ± 0.1%) was prepared. Strong texture existed parallel to building direction of < 110 > , and large geometrically necessary dislocations (GNDs) density were distributed within the grains. The proportion of large-angle grain boundaries was about 12% higher than that in the building direction due to the larger number of fine grains in the horizontal direction, and the average grain size was reduced by twice. Further stable subgrains (∼368 ± 99 nm) were attributed to substructure induced by dislocation networks, which was mainly the combined effect of large residual stress, low stacking fault energy, and internal heat treatment effects.

Laser shock peening of AlCoCrCuFeNi high-entropy alloy fabricated by laser powder bed fusion: An enhanced oxidation-resistance mechanism at high-temperature

The high-temperature oxidation behaviors of laser powder bed fusion (LPBF)-fabricated AlCoCrCuFeNi high-entropy alloy (HEA) with and without laser shock peening (LSP) were investigated over different exposure durations and temperatures. Results revealed that LSP converted the surface stress from tensile to compressive, while also inducing grain refinement and high-density dislocations. Under high temperatures, the coupled effects of grain refinement and compressive residual stress resulted in the formation of dense protective oxidation scales, which inhibited the inward diffusion of oxygen. LSP improved the high-temperature oxidation resistance of LPBF-fabricated AlCoCrCuFeNi HEA, and the enhanced oxidation-resistance mechanisms were discussed.

Residual stresses effects on fatigue crack growth behavior of rib-to-deck double-sided welded joints in orthotropic steel decks

Rib-to-deck (RTD) innovative double-sided welded joints have the potential to enhance the fatigue resistance of orthotropic steel decks (OSDs). However, welding residual stress (WRS) has been reported to be a contributing factor to fatigue cracking of steel bridges. This paper performed fatigue crack growth of the RTD innovative double-sided welded joints of OSD considering WRS. Firstly, a thermal-mechanical sequential coupling finite element model (FEM) of the RTD double-sided welded joints was established. The WRS distribution along the direction of deck thickness was analyzed. Secondly, the FEM of the OSD segment with crack was established. The fatigue crack behavior of RTD double-sided welded joints under the combined action of vehicle load and WRS was studied. Finally, the influences of initial crack on fatigue life was analyzed. Results indicate the distribution of the transverse WRS along the direction of deck thickness is tension-compression-tension stress, which has the characteristics of the sinusoidal function. The ∆ Keff value increases significantly considering WRS than without considering WRS during crack growth. WRS has a significant effect on fatigue life, and the fatigue life of the weld toe without considering WRS is about twice that of considering WRS. The crack depth and aspect ratio ( a0/ c0) of the initial crack affect the fatigue life of RTD double-sided welded joints.

Experimental study on fire resistance of high strength Q960 steel columns under axial compression

In order to obtain the mechanical behavior of H-shaped high-strength Q960 steel column under axial compression in fire, the bearing capacity tests of two Q960 steel columns at ambient temperature and fire resistance tests of six Q960 steel columns at elevated temperature were carried out. By considering different slenderness ratios, load ratios, and heating rates of the test columns, the furnace temperature, column temperature, lateral displacement, and axial displacement were measured and recorded. Then, critical temperature, fire resistance, and failure mode of the columns were obtained. The thermal-mechanical coupling analysis model for the Q960 steel column was established by using ABAQUS finite element analysis software. After verifying the accuracy of the model, parameter analysis was carried out to investigate the effects of load ratio, slenderness ratio, geometric imperfection, thermal creep, residual stress, and steel strength on the fire resistance of steel columns. Based on the test data and analysis results, a fire resistance design method for high-strength Q960 steel columns under axial compression is proposed.

Recent advanced thermal interfacial materials: A review of conducting mechanisms and parameters of carbon materials

Understanding the effect of process-induced residual stresses on the final shape of fiber-reinforced polymer composites is critical due to their widespread use in structural applications. It is crucial for more dependable composite production, as residual stresses change the internal stress level of the composite component during service life, and residual shape distortions may prevent the part from achieving the required geometrical tolerances. Residual strains are the result of many interplays among physical processes, such as heat transfer, material flow, polymerization, crystallization, or heat transfer. Numerical process models must be constructed instead of time-consuming and inefficient trial-and-error procedures to design and optimize the composite manufacturing process digitally. This study aims to review the model creation and applications for predicting residual stresses and form distortions in composite manufacturing. Uses for both thermoset and thermoplastic composites are investigated in detail. Predictions of the process-induced deformations of laminated composite structures have been made using elastic constitutive models, such as a plane strain finite element model with a cure-hardening, instantaneous linear elastic constitutive model. to learn more about the factors that lead to shape distortion and how they can be reduced, such as by adjusting cure cycles, tool surfaces, geometry, or lay-up.

How epoxy cure profiles (may) impact performance of non-crimp fabric composites

Glass fibre reinforced polymers made from quasi uni-directional non-crimp fabrics have recently been shown to suffer from a specific damage mechanism. This damage mechanism is dominated by off-axis cracks in the off-axis backing bundles of the fabrics. In addition, research results have indicated that the onset and propagation of such off-axis cracks may be influenced by the residual stresses that arising from the manufacturing process used to produce the Glass fibre reinforced composites. The current article investigates the potential effect of residual stresses on the fatigue life through an experimental set-up that involves tailored cure profiles and image based evaluation of tensile test experiments.

Isogeometric topology optimization for infill designs of porous structures with stress minimization in additive manufacturing

AbstractPorous structures by additive manufacturing have fascinating and compelling performance compared with solid structures. The stress‐related porous infill designs which could greatly mitigate the effects of the intrinsic high residual stress in additive manufacturing process have gained increasing attention. In the current work, we propose a promising Isogeometric Topology Optimization (ITO) method for porous infill structures with stress minimization to avoid the occurrence of stress concentrations in additive manufacturing. The IsoGeometric Analysis (IGA) and induced p‐norm aggregation are utilized to develop a stress‐minimization topology description model for infill design, which can remove the mesh dependency and offer benefits for improving numerical accuracy and convergence stability. We also introduced global volume constraints to easily control the usage of material and eliminate the over‐fine structures affecting the printing accuracy. Several numerical examples are performed to demonstrate the effectiveness and advantages of the proposed ITO method on porous infill designs with stress minimization. The laser powder bed fusion (LPBF) technique is employed to fabricate several prototypes, and the performance are evaluated by experiments. The advancements of our work are demonstrated effectively, which is adapted for additive manufacturing and practical application.

The mechanism of the effect of dual-sided waterjet peening on the surface integrity and fatigue performance of 12 mm thick Inconel 718

This study aims to explore the mechanisms of residual stress formation and the effects on fatigue performance of 12 mm thick Inconel 718 under single-sided one-pass, two-pass, and dual-sided two-pass waterjet peening. Finite element models for waterjet peening and fatigue analysis were established using ABAQUS and Fe-safe, respectively. The study focused on analyzing the residual stresses, surface roughness, and fatigue cycle numbers of Inconel 718 after waterjet peening. The results were validated by conducting waterjet peening experiments and post-peening fatigue tests to ensure their reliability. The research findings indicated that the induced residual compressive stress was most effective with dual-sided two-pass waterjet peening, followed by single-sided two-pass and single-sided one-pass waterjet peening. Among them, after WJP-290 mm/s peening, the maximum residual compressive stresses for dual-sided two-pass, single-sided two-pass, and single-sided one-pass were 718.6, 906.4, and 1042.7 MPa, respectively. The maximum residual compressive stress depth after WJP-230 ∼ 290 mm/s peening was positively correlated with the jet velocity. Surface deterioration occurred after WJP-350 mm/s peening, leading to a significant reduction in the induced residual stress effect. After WJP-230 mm/s peening, the specimen exhibited an overall residual compressive stress of about 507.7 MPa at a depth of approximately 13.1 μm, with a total residual compressive stress depth of about 34.8 μm. Increasing the jet velocity to 290 mm/s shifted the maximum residual compressive stress depth to about 27.2 μm, with a maximum residual compressive stress increase of about 535 MPa, reaching 1042.7 MPa. At the same time, the overall residual compressive stress depth also increased to 39.9 μm. After increasing the jet velocity to 350 mm/s, a maximum residual compressive stress of about 708.7 MPa was induced at a depth of approximately 11.9 μm. The surface roughness, average roughness, and maximum roughness of the specimens were positively correlated with the jet velocity, with the most significant morphological changes occurring at the edges of the waterjet peened area, which coincided with the region prone to fatigue fracture in the cyclic fatigue tests. Increasing the number of jet impacts had a “peak-to-valley” effect on the surface of the peened specimens, making the surface flatter. The specimens peened with dual-sided waterjet showed significantly higher fatigue cycle numbers than those peened with single-sided waterjet. After WJP-230 mm/s peening, the fatigue life at stress levels of 93, 132, and 150 MPa was approximately 2,182,922, 258,000, and 56,575 cycles, respectively, which increased by about 399 %, 274 %, and 218 % compared to single-sided one-pass peening and by about 165 %, 139 %, and 125 % compared to single-sided two-pass peening.

Influence of post-expansion residual stress on the fatigue life of the supercharged boiler

The stress distribution on boiler tubesheets becomes very complex due to the combined effects of thermal-mechanical load and residual stress from expansion in numerous expanded joints. This study determined the residual stress distribution generated by the expansion process on the boiler drum, which was used as the initial stress state boundary to simulate continuous steam charging and discharging cycles. Different fatigue assessment methods were employed to evaluate the impact of `residual stress on fatigue life. The results indicated that the residual stress exhibited higher values in the central region and lower values on the sides. When considering the post-expansion residual stress, there was a reduction of 10.4%/20% and 8.9% in the permissible number of cycles based on the maximum shear stress and distortion energy theories, respectively. It is crucial to account for the fatigue weakening caused by the expansion process in the fatigue evaluation of pressure vessels.

Analysis of Crack Propagation Behaviors in RPV Dissimilar Metal Welded Joints Affected by Residual Stress.

In severe service environments, the presence of high local residual stress, significant organizational gradient, and nonlinear changes in material properties often leads to stress corrosion cracking (SCC) in dissimilar metal welded (DMW) joints. To accurately predict the crack growth rate, researching the initiation and propagation behavior of SCC cracks in DMW joints under residual stress (RS) is one of the most important methods to ensure the safe operation of nuclear power plants. Using the extended finite element method (XFEM), the crack propagation behaviors in DMW joints under different RS states are predicted and compared. The effects of RS, crack location, and initial crack length on crack propagation behavior are investigated. The crack in a DMW joint without RS deflects to the material of low yield strength. High residual stress urges the crack growing direction to deflect toward the material of high yield strength. Young's modulus has little impact on the crack deflection paths. The distance between the specimen symmetric line and the boundary line has little effect on the crack initiation and propagation within the RS field. A long initial crack is more likely to initiate and propagate than a short crack. To a long crack and the crack that is far from the interface of two materials, the impact of residual stress on the crack propagation path is significant when it is located in a material with high yield strength, while when the initial crack is located in the material with low yield strength, RS has a great influence on the deflection of a short crack growth direction on the condition that the crack is adjacent to the interface.

Rewelding Residual Stress of Fatigue Crack at U-Rib-to-Deck of an Orthotropic Steel Deck

The orthotropic steel deck is a prevalent stiffening girder structure utilized in long-span cable-stayed bridges and suspension bridges. Nonetheless, the issue of fatigue cracking has persisted in in-service orthotropic steel decks, significantly impacting the longevity of bridges. This study examines the analysis of the distribution of residual stress during the rewelding process of a fatigue crack at the U-rib-to-deck-plate joint of an orthotropic steel bridge deck. Additionally, the impact of the initial welding and the stiffness of the boundary constraint on the residual stress field during rewelding is discussed. The findings indicate that the removal of the fatigue crack prior to rewelding alleviates the transverse residual stress caused by the initial welding. After undergoing the rewelding procedure, both the transverse residual stress and the longitudinal residual stress exhibited a significant stress peak. More precisely, the transverse tensile stress underwent a rise from 21 MPa to 385 MPa, while the longitudinal tensile stress experienced an increase from 345 MPa to 525 MPa. Furthermore, the range of tensile stress within the longitudinal residual distribution expanded by 88%. Moreover, the stress redistribution during the rewelding of the local fatigue crack varied depending on the constraints imposed on the steel bridge deck. Notably, the transverse residual stress increases by 40.6% when compared to the absence of constraints. The findings of this research offer valuable insights for the implementation of rewelding repair techniques on steel bridge decks, emphasizing the significance of considering the effects of residual stresses induced during the rewelding process.

Modelling of glass matrix composites by the Coupled Criterion and the Matched Asymptotic Approach. The effect of residual stresses and volume fraction

The fracture toughness of glass can be improved by including ceramic reinforcing platelets. Among others, Al2O3 platelets are proposed as an environmentally friendly and low-cost solution. One of the critical points in the design of this composite is the generation of residual stresses after cooling in manufacture, due to the thermal expansion mismatch between the two materials. In this paper, the effect of these residual stresses and the role of the volume fraction are studied, following a methodology based on the Coupled Criterion together with the Matched Asymptotic Expansion. The model is validated through a comparison with experimental results found in the literature.