Residual Stress Test Research Articles

Electro-chemo-mechanical deterioration of high-dose electron irradiated Li1.3Al0.3Ti1.7(PO4)3 electrolyte

Solid-state electrolytes (SSEs) hold promises for aerospace and satellite applications, owing to their high-voltage and low-temperature stability. However, concerns about electrochemical degradation under high-energy radiation hinder their widespread use in space. To this end, a NASICON-type Li1.3Al0.3Ti1.7(PO4)3 (LATP) electrolyte with high ionic conductivity at room temperature was selected, and the effects of high-dose electron irradiation on the microstructure as well as electrochemical and mechanical properties of electrolyte were investigated by using neutron powder diffraction (NPD), NPD stress analysis, micro-computed tomography, nanoindentation, and XRD residual stress test. It was confirmed that LATP SSEs held good resistance to irradiation at absorbed doses of 1 and 2 MGy with negligibly performance degradation, while irradiation at high doses induced a rapid decrease in the Young modulus and hardness of SSEs and introduced a tensile stress of 65.79 MPa at up to 10 MGy absorbed dose, which increased the cracking tendency and the risk of lithium dendrite growth in the solid-state electrolyte. NPD revealed that the reduction of lithium vacancies at the M1 site of the irradiated SSEs was the critical factor for the ion transport performance degradation. This is evidenced by a significant increase in impedance, up to 453 Ω, and an increase in the activation energy for ion transport to 0.501 eV.

Research on Dynamic Evolution of Residual Stress Based on Simulation of Piston Manufacturing Process

Rather than focusing on the residual stress generated from casting, machining, or heat treatment unilaterally, a comprehensive research method to consider the whole dynamic evolution of residual stress is proposed. The cast iron piston is taken as the research object to establish a continuous simulation model for its manufacturing. Firstly, a simulation model of piston casting is established to analyze the stress change. Subsequently, through the machining and heat treatment simulation of the piston, the variation law of residual stress before and after machining is analyzed. Different process parameters are designed to study the redistribution mechanism of residual stress. Residual stress tests are further conducted on the processed piston products. The results indicate that shakeout can effectively remove 60% to 80% of the residual stress. The removal of materials results in overall residual stress release and redistribution for the piston, and the piston releases 10% to 40% of the residual stress after machining. The heat treatment of the machined piston can effectively reduce the residual stress with a maximum reduction of 27.1%. The good consistency between experimental results and simulation results further confirms the feasibility of the comprehensive research method. This study is beneficial for achieving low stress manufacturing of pistons and improving their working performance.

A stress test method of polycrystal 95%Al2O3 based on Vickers indentation-induced cracks

A stress test method of polycrystal 95%Al2O3 based on Vickers indentation-induced cracks

Surface integrity and mechanical properties of small elements fabricated through LPBF and post-processed with heat treatment and abrasive machining

The present research analyzes the impact of heat treatment atmosphere followed by finishing surface machining of small elements of Inconel 939 fabricated through laser powder bed fusion (LPBF). The analysis involved annealing in two gas mediums, solution treatment, and aging to achieve the desired microstructure and mechanical properties. The finishing surface was performed using various variants of abrasive machining. A more than fivefold reduction in the average roughness height Ra from 5.6 µm to 1.15 µm was achieved using metal balls as an abrasive, which was required for further processing. Residual stress tests have shown that due to heat and abrasive treatment, tensile stresses change into compressive ones. After printing, samples are characterized by tensile residual stresses on the surface (+ 428 MPa), while after heat treatment, compressive stresses occur (− 179 MPa). Abrasive machining with metal balls increases the value of compressive stresses to − 464 MPa. In addition, the impact of post-processing on the microstructure of Inconel 939 was discussed in terms of mechanical properties. The yield strength of 1184 MPa and elongation values of 19.3% were obtained for samples after HT in an argon atmosphere and abrasive machining with a ceramics roller. These studies provide valuable new information on the effective heat treatment and optimization of the finishing machining of Inconel 939, especially in achieving the desired surface roughness, microstructure, and mechanical properties for aerospace applications.

Using Iterative Correction to Improve the Accuracy of the Blind-Hole Welding Residual Stress Test.

An iterative correction method for the stress release coefficient, leveraging numerical simulation, has been innovatively developed to address the significant error issues associated with the blind-hole method in high-stress residual stress testing of steel structures. This method effectively reduces measurement error in high residual stress regions through a discriminant iteration process. The finite element analysis technology was employed to accurately simulate the blind-hole method's test process, and additionally, Python was utilized for customizing the secondary development of ABAQUS software, thereby automating and optimizing the method. When compared with simulation and experimental data from the welding process, the efficiency, accuracy, and reliability of the correction method have been verified. The proposed method eliminates the need for tedious calibration experiments inherent in traditional methods, significantly enhancing the test's automation level and convergence speed, and ensuring measurement accuracy, which provides an innovative solution for the accurate evaluation of residual stress in steel structures.

Residual stress tests and predictive model of friction stir welded normal-strength aluminium alloy H-shaped sections

Residual stress tests and predictive model of friction stir welded normal-strength aluminium alloy H-shaped sections

Non-Destructive Hardness Indentation Measurement of Residual Stress on Large Aerospace Forged Components at the Engineering Site Based on Impact Hardness Tester.

Large forgings are crucial in aerospace applications; however, the residual stresses generated during their forming and heat treatment seriously affect their serviceability. Therefore, the non-destructive detection of residual stresses in large forgings is of far-reaching significance for ensuring the quality of forgings and realising precision machining. Although a variety of detection methods are available, there is still a lack of a programme that can comprehensively, accurately and non-destructively measure the residual stresses in large forgings. This study is dedicated to exploring the application of the bouncing impact indentation method in the non-destructive testing of residual stresses in large forgings. Through in-depth finite element simulations and orthogonal scheme analyses, we found that the elastic modulus, yield strength and work hardening indexes have significant effects on the impact indentation process. Further, we establish the dimensionless function of residual stress and indentation parameters, and successfully obtain the inversion algorithm of residual stress. The relative error of the calculated values of the indentation curves hm and hr in the simulation with reference values is not more than 3%, and the relative error of the corrected Pm inversion values for most virtual materials is not more than 5%. The folding elastic modulus and apparent elastic modulus obtained by inversion are controlled within 10%, which demonstrates a high value for engineering applications. In addition, we innovatively express the research results in the form of 3D stress diagrams, realising the digital expression of 3D residual stresses in large forgings based on feature point measurements and contour surface configurations, which provides intuitive and comprehensive data support for engineering practice.

Tensile Coupon Testing and Residual Stress Measurements of High-Strength Steel Built-Up I-Shaped Sections

High strength structural steels (with yield stresses greater than 65 ksi) may have notably different material characteristics when compared to structural steels conventionally used in building construction [i.e., ASTM A992/A992M (2022) or A572/A572M Gr. 50 (2021)]. This paper presents findings from an experimental program that investigated the material characterization of ASTM A656/A656M Gr. 80 (2024) plate steel. The results obtained were compared to conventional ASTM A572/A572M Gr. 50 steel. Two types of testing were performed for this work: tensile coupon testing and residual stress testing. The tensile coupon testing was carried out for both the A656/A656M Gr. 80 and A572/A572M Gr. 50 plate material. The A656/A656M Gr. 80 plate material showed more variation between the two different plate thicknesses in both mechanical behavior and microstructure due to differences in steel production. The 0.375 in. thick plate exhibited a clear yield plateau with an ultimate/yield stress ratio similar to the Gr. 50 material. In contrast, the 0.5 in. plate did not have a yield plateau and reached lower ultimate strain. The residual stress testing was performed using a sectioning technique for one A572/A572M Gr. 50 and five A656/A656M Gr. 80 built-up sections that were fabricated from 0.5 in. and 0.375 in. plate material. Residual stresses obtained from measurements were compared to previously published predictive models. The ECCS model and BSK99 models were found to be reasonable predictors of residual stresses for all specimens except the one section fabricated from 0.5 in. thick Gr. 80 plate. When comparing the Gr. 50 and Gr. 80 specimens of the same cross-sectional geometry, the residual stresses were similar, implying that cross-sectional geometry is more prevalent than the nominal yield stress in determining residual stresses in built-up I-sections.

Residual stress distribution and relaxation in U-rib full penetration welds by ultrasonic impact treatment

Residual stress distribution and relaxation in U-rib full penetration welds by ultrasonic impact treatment

Multiscale simulation combined with experimental investigation on residual stress and microstructure of TC6 titanium alloy treated by laser shock peening

Multiscale simulation combined with experimental investigation on residual stress and microstructure of TC6 titanium alloy treated by laser shock peening

Ultrasonic immersion testing of residual stress in plates using collinear Lamb wave mixing technique

Ultrasonic immersion testing of residual stress in plates using collinear Lamb wave mixing technique

Enhanced fretting fatigue strength of TC11 titanium alloy using laser-assisted ultrasonic surface rolling process

Enhanced fretting fatigue strength of TC11 titanium alloy using laser-assisted ultrasonic surface rolling process

Characteristics of 2D Ultrasonic Vibration Incremental Forming of a 1060 Aluminum Alloy Sheet.

Currently, 1060 aluminum alloy is widely applied in the electronics industry, construction, the aerospace field, traffic engineering, decorations, and the consumer goods market for its good chemical, physical, and mechanical properties. In general, excellent processing property is necessary and important for the manufacturing of complicated panels. In this paper, a special 2D ultrasonic vibration incremental forming method is designed to improve its plasticity and mechanical properties. Three kind of processing methods, including traditional single-point incremental forming, longitudinal ultrasonic vibration incremental forming, and 2D ultrasonic vibration incremental forming, are used for the flexible manufacturing of cones and cylindrical cups of 1060 aluminum alloy sheet. Then, micro-hardness tests, residual stress tests, and scanning electron microscopy tests are carried out to probe the changes in micro-structure and mechanical properties and to analyze the effects of different types of ultrasonic vibration on the plasticity and fracture characteristic of 1060 aluminum alloy. It is proven that 2D ultrasonic vibration facilitates the improvement of plasticity and surface qualities of 1060 aluminum alloy better than the other two processing methods. Therefore, the novel 2D ultrasonic vibration incremental forming process possesses substantial application value for the flexible and rapid manufacturing of complicated thin-walled component of aluminum alloy.

Stress relief simulation for post-weld heat treatment process of pressure equipment: Creep constitutive equation considering temperature and stress variations

Stress relief simulation for post-weld heat treatment process of pressure equipment: Creep constitutive equation considering temperature and stress variations

Effect of contact stress and slip amplitude on fretting fatigue behaviour of ultrasonic surface nanocrystallized TC11 titanium alloy

Effect of contact stress and slip amplitude on fretting fatigue behaviour of ultrasonic surface nanocrystallized TC11 titanium alloy

Investigation of Friction Hydro-Pillar Processing as a Repair Technique for Offshore Mooring Chain Links

Repairing links of offshore mooring chains has presented a significant industry challenge, primarily arising from modifications in material properties, encompassing alterations in microstructure, hardness, and residual stress. In this context, the present work investigates the method of friction hydro-pillar processing (FHPP) applied to R4 grade mooring chain steel. Joints in as-repaired and post-weld heat treatment (PWHT) conditions were subjected to residual stress (RS) tests using the neutron diffraction technique, microhardness mapping, and microstructural evaluations. The process generated peaks of tensile and compressive stresses in different directions and hardness below that of the parent material in the softening zone. The friction zone promoted high hardness levels in the thermo-mechanically affected zone (TMAZ) with a maximum of 19% of the ultimate tensile strength of the parent material. As expected, the PWHT restored the RS and reduced the hardness; however, 4 h PWHT allowed the elimination of a hardness higher than that of the base material.

Effect of multiple weld repairs on fatigue strength of bogie frame of railroad vehicle

In the welded structure of railroad vehicles, the bogie frame requires a service life more than 25 years, cracks occur in the weld zone owing to the application of repetitive fatigue loading during operation. When cracks occur and propagate in the weld zone, they are removed through gouging, and gas metal arc welding is performed for repair. After the first weld repair, the second weld repair process is performed if crack is visible in the same area. In this study, the effects of repetitive repair welding on the fatigue characteristics were investigated using materials applied in railway vehicle structures. Three types of specimens (weld specimen, first weld repairs specimen, and second weld repairs specimen) were prepared, and fatigue and residual stress tests were performed. The results indicated that the weld specimen had the longest fatigue life, and the first weld repairs specimen had the shortest fatigue life. The fatigue life of the second weld repairs specimen was longer than that of the first weld repairs specimen. Residual stress tests and finite-element analysis results indicated that the first weld repairs specimen had the shortest fatigue life among the specimens tested, because the highest residual stress was generated.

Investigation on wear behavior for SUS420 steel gear based on discrete laser surface melting

Investigation on wear behavior for SUS420 steel gear based on discrete laser surface melting

An approximate formula for the Rayleigh wave velocity in the machined surface with residual stress

The present paper is concerned with the Rayleigh wave propagation in the machined surface with a thin damaged layer with residual stress. We assume that the layer and the half-space are bonded perfectly to each other. Biot’s theory of small deformations influenced by initial stress forms the basis for this study. With the help of the effective boundary condition method, a third-order approximate secular equation of Rayleigh waves is established for the case that the layer and half-space are both orthotropic. In addition, an explicit third-order approximate formula for the Rayleigh wave velocity is derived from the secular equation. By considering a sample of silicon wafer by fine grinding with fine abrasive grains, the accuracy of the approximate formula has been verified. This study is meant to serve as the mathematical foundation for non-destructive testing of residual stress in the practical applications.

Thermal relaxation of compressive residual stresses in surface gradient nanostructure of TC11 titanium alloy

Thermal relaxation of compressive residual stresses in surface gradient nanostructure of TC11 titanium alloy