Design, fabrication, and characterization of a novel cantilever-based PMUT incorporating a central spring-like folded beam with enhanced transmission performance for air applications.

Study on residual stress relaxation and small crack propagation behavior of laser shock peened FGH4098 alloy

Improved corrosion resistance of laser directed energy deposited AlCoCrFeNi2.1 eutectic high-entropy alloy via microstructure and residual stress control

Microscopic mechanism of enhancing residual stress on machined surface of Inconel 718 by ultrasonic vibration

Influence of residual stress on the fracture toughness of semi-elliptical cracks in aluminum: a numerical and experimental investigation

La-induced microstructural regulation and residual stress mitigation in vacuum-brazed Al2O3 ceramic/AgCuTi/316 stainless steel joints

Influence of single point incremental forming induced residual stresses and surface topography on the high-cycle fatigue performance of AA6061-T6

Fatigue life prediction of orthotropic steel decks under vehicle loads considering welding residual stress relaxation

A computational approach is proposed to estimate the fatigue life of medical welded structures by explicitly considering residual stress redistribution during cyclic loading. Finite element simulations were performed to obtain initial residual stress distributions after welding, followed by elastic-plastic shakedown analysis under cyclic loads. A total of 24 welded joint models were analyzed, with nominal stress amplitudes ranging from 80 to 160 MPa. Results indicate that residual stress relaxation reached 18–32% after 10⁴ loading cycles, significantly affecting fatigue damage accumulation. Compared with conventional fatigue models neglecting residual stress evolution, the proposed method reduced life prediction error from 41.2% to 14.7% when benchmarked against experimental fatigue data reported in medical device standards.

Investigation on the machined surface residual stress of high-speed cutting of nickel-based superalloy GH4169

Monitoring equity drawdown risk requires real-time indicators that can be implemented without look-ahead bias and that may add information beyond standard volatility measures. This study develops a leakage-safe residual-stress indicator from cross-sectional PCA reconstruction errors in U.S. sector excess returns. Using daily adjusted prices for SPY and 11 U.S. sector ETFs, sector excess returns are computed relative to SPY, the common component is estimated with principal component analysis (PCA), and residual stress is defined as the cross-sectional root-mean-square magnitude of out-of-sample reconstruction residuals. The PCA mapping is estimated using information available only through t−1, the stress score is computed at t, and high-stress regimes are defined using rolling train-only quantile thresholds shifted forward by one trading day. The results show that realized volatility remains the stronger standalone benchmark in overall early-warning classification performance. Residual stress is therefore not proposed as a replacement for volatility. Instead, it is most useful as a complementary indicator of cross-sectional market dislocation. In the baseline sample, residual-stress spikes cluster around several drawdown-onset episodes, and conditional regime analysis shows that when volatility is low, high residual stress is associated with a higher probability of a drawdown onset within the next H=21 trading days than the low-stress/low-volatility regime. Event-overlap and lead-time diagnostics suggest that residual stress can identify some onset episodes not captured by a simple volatility-threshold rule, although its main incremental value lies in conditional risk stratification rather than systematically earlier triggering. The contribution of the paper is to develop a leakage-safe and interpretable residual-stress diagnostic for conditional drawdown-risk monitoring. The evidence supports a balanced interpretation: residual stress adds state-dependent information beyond standard volatility measures, especially in otherwise low-volatility states, but it does not dominate realized volatility as a standalone predictor.

Numerical and experimental investigation of residual stress polarity and distortion evolution in laser powder bed fusion of IN718 spur gears

Crimping and deployment of coronary stents involve severe finite deformations, multibody contact, and complex loading-unloading sequences that critically influence their structural integrity and long-term performance. This study presents a 3D phase-field fracture framework for simulating the onset and evolution of metal stent failure during crimping and balloon-assisted deployment in coronary arteries modeled as an anisotropic, hyperelastic material. The proposed framework combines finite-strain elastoplasticity with a phase-field description of ductile fracture, implemented as a dedicated user element (UEL) in Abaqus and validated against experimental stress-strain data for stainless steel stents to accurately capture plastic deformation, damage initiation, and softening. In parallel, a second UEL is developed for the arterial wall, incorporating anisotropic hyperelasticity to represent the layered mechanical response of intima, media, and adventitia. Fully coupled simulations of the stent-balloon-artery system reproduce the complete crimp-hold-release and expansion sequence, explicitly capturing contact interactions, stress localization at crowns and connectors, and progressive damage accumulation under realistic physiological conditions. The simulations reveal that fracture is initiated already during the crimping phase and continues to evolve during balloon expansion, resulting in localized damage zones, residual stresses, and elastic recoil after balloon deflation. Comparative analyses of representative stent designs (e.g., open-cell and closed-cell configurations with varying strut thickness and geometry) demonstrate how design features, loading paths, and arterial anisotropy govern damage evolution, failure progression, and post-deployment mechanical performance. The proposed model establishes a robust computational framework for failure-aware evaluation of coronary stents under finite strains, providing new insights for optimizing stent design and deployment strategies. The corresponding source code in this study is openly available at https://doi.org/10.25835/666phabc to support further research.

Exploring Nanoindentation-Based Residual Stress Evaluation in Laser Powder Bed Fusion Fe-Cr-Al Alloys with x-ray Diffraction Reference

Association of NT-proBNP With Clinical Outcomes in Patients Undergoing Transcatheter Tricuspid Valve Intervention.

Perovskite/silicon tandem solar cells (PSTSCs) face a significant challenge in achieving uniform deposition of a self-assembled monolayer (SAM) on industrial-scale microtextured silicon substrates. In particular, nonuniform SAM coverage not only hinders the formation of high-quality perovskite films but also introduces additional interfacial defects and leads to further stress accumulation, thereby degrading device efficiency and stability. However, the underlying mechanisms behind nonuniform SAM coverage remain unclear. Here, we develop a comprehensive optoelectrothermal coupled simulation model to systematically investigate the optoelectronic coupling, carrier-ion dynamics, thermal-stress behavior, and corresponding mitigation strategies of nonuniform SAM-based PSTSCs. The simulation results reveal that nonuniform SAM coverage leads to inhomogeneous carrier transport and significantly increases carrier recombination in SAM-uncovered regions, particularly at the pyramid peaks, resulting in severe performance degradation. Additionally, nonuniform SAM coverage exhibits low tolerance to variations in perovskite film quality, interfacial passivation, reverse breakdown, and ion migration behavior. Moreover, residual stress induced by thermal mismatch shows a clear morphology dependence, with nonuniform SAM coverage leading to localized stress accumulation. Despite these adverse effects, we find that the performance degradation caused by nonuniform SAM coverage can be mitigated by increasing the photocurrent in the perovskite top cell, offering insights into designing high-efficiency and stable PSTSCs.

Flexible all-perovskite tandem solar cells (PTSCs) are promising for lightweight photovoltaics, yet their mechanical degradation under bending remains poorly understood. Although bending instability has often been attributed to brittle fractures, halide perovskites are mechanically soft materials. Here, we demonstrate that bending-induced degradation in flexible PTSCs primarily associated with strain-induced evolution of residual-stress accumulation prior to crack formation, while elastic-modulus engineering through grain-boundary polymerization mitigates this mechanically induced degradation. Grazing-incidence X-ray diffraction analyses reveal that repeated bending accumulates residual stress of both wide-bandgap and narrow-bandgap perovskite layers in PTSCs, leading to fatigue-associated degradation and enhanced nonradiative recombination even in the absence of visible cracks. To address this intrinsic limitation, a dual-layer grain-boundary in situ polymerization strategy is introduced for both perovskite layers, enabling elastic relaxation and suppressing residual-stress accumulation. As a result, flexible PTSCs achieve a power conversion efficiency of 24.97% and retain over 90% of their initial efficiency after 5000 bending cycles at a radius of 5 mm. This work establishes elastic-modulus engineering as a key design principle for mechanically robust flexible perovskite tandem solar cells.

To elucidate the mechanism by which acidification influences wellbore stability in deep reservoir formations, this study investigates the rheological and mechanical behaviors of the carbonate rock subjected to high-temperature acid etching. A novel experimental system was developed to characterize the stress relaxation behavior of the acid-etched carbonate rock, and the characteristics of the stress relaxation curves under various acid etching conditions and strain levels were systematically analyzed. Combined with Burgers model and the Levenberg–Marquardt algorithm, the evolution of rheological parameters of the carbonate rock under different acid etching regimes was quantitatively evaluated. The results indicate that the acid-etched carbonate rock exhibit significant rheological mechanical properties due to the presence of developed microcracks and complex pore structures. Under the identical acid etching duration and temperature, the initial stress, residual stress, and time required for stress relaxation stabilization all increase with increasing the strain level. Overall, the stress relaxation magnitude prior to the core fracture ranges from 15 to 25 MPa, and the stabilization time for the core stress relaxation falls between 5 and 7 h. The stress relaxation behavior of the acid-etched carbonate core is well described by the Burgers model. At fixed strain levels and temperatures, the instantaneous shear modulus G_{1} decreases linearly with extended acid etching time, whereas the instantaneous shear modulus G_{2} and the viscosity coefficients eta_{1} and eta_{2} exhibit exponential degradation. The final variation ranges of the key rheological parameters are determined as follows: instantaneous shear modulus G_{1} ranges from 5 × 103 to 2 × 104 MPa, instantaneous shear modulus G_{2} ranges from 6 × 105 to 2 × 106 MPa, viscosity coefficient eta_{1} ranges from 2 × 107 to 8 × 107 MPa h, and viscosity coefficient eta_{2} ranges from 1 × 105 to 1.2 × 106 MPa h. Furthermore, the evolutionary equations correlating the global model fitting parameters with the porosity of acid-etched samples are established, using acid etching time as an intermediate variable. The results of this study provide a theoretical basis for the analysis of wellbore stability after acidification and the selection of acid fracturing completion methods of deep reservoirs.

Reliable qualification of collapse resistance is critical across pressurised cylindrical shells ranging from offshore risers and subsea cables to aerospace tanks and even biological ducts. Existing approaches either rely on costly hyperbaric chambers or oversimplified geometric models that neglect the forming-induced residual stresses and imperfections. Here, we propose a back-inferred equivalent-material method (EMM), which transforms a simple benchtop flat-plate compression test result into a nonlinear constitutive law that implicitly embeds cold work, residual stress, friction, and small-scale compliance. Embedding this equivalent law into a homogeneous finite-element model reproduces hydrostatic collapse without the need for full-scale testing. We demonstrate the method on flexible-pipe carcass layers and steel-strip reinforced thermoplastic pipes, showing close agreement with explicit-geometry simulations and hyperbaric measurements. More broadly, the geometry-agnostic formulation enables rapid, low-cost, and physically faithful qualification across diverse layered shells, offering a general route to replace hyperbaric testing in industries spanning energy, aerospace, and biomedical engineering.

Residual strains in human versus animal aortas: a reconciliation of apparent differences.