Scholarlink

Background <p>Shape memory alloys (SMAs) have revolutionized structural retrofitting by leveraging their intrinsic shape memory effect (SME) to generate pre-stress through non-destructive thermal activation. While offering superior advantages over passive repair methods, the long-term effectiveness of SMA-based retrofitting critically hinges on the retention of recovery stress under cyclic fatigue loading. However, the degradation mechanisms governing recovery stress under combined phase transformation and fatigue remain poorly quantified, impeding the optimization of SMA applications in engineering practice.</p> Objective <p>This study systematically investigates the fatigue-induced degradation of recovery stress in Nickel-Titanium (NiTi) SMAs under high-stress cyclic loading, aiming to unravel the interplay between macroscopic mechanical behavior and microstructural evolution.</p> Method <p>A multi-scale experimental framework integrates macroscopic mechanical testing (high-stress cyclic loading at five stress levels) with microscopic fracture analysis (scanning electron microscopy). Empirical relationships between stress amplitude and fatigue life (<i>N</i><sub><i>i</i></sub>) / recovery stress loss rate (<i>RSLR</i>) are established, while crack propagation modes are quantitatively correlated to stress amplitudes.</p> Results <p>Fatigue life and deformation increments exhibit inverse proportionality to applied stress amplitude. Concurrently, experimental findings identify a critical yield stress threshold (385&#xa0;MPa) that governs recovery stress degradation. Below this threshold, <i>RSLR</i> remains negligible (2.13 × 10<sup>–5</sup>&#xa0;MPa/cycle), preserving &gt; 96% of initial recovery stress after 742,229 cycles. Above this threshold, transverse crack propagation leads to an accelerated degradation of the recovery stress.</p> Conclusion <p>The identified yield stress threshold and empirical models provide a mechanistic foundation for designing fatigue resistant SMA retrofitting systems. By linking macro-mechanical degradation to microstructural crack evolution, this work advances the predictive capability for recovery stress retention, enabling optimized SMA deployment in critical infrastructure under high-stress service conditions.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Quantifying Recovery Stress Degradation in NiTi Shape Memory Alloys Under High-Stress Cyclic Loading: Mechanistic Insights for Structural Retrofitting

  • 期刊论文

  • 发表日期：

    2025年8月25日

查看全文
  • Z. Fei,
  • D. Guo,
  • J. Deng,
  • X. Li,
  • J. Liang

摘要

Background

Shape memory alloys (SMAs) have revolutionized structural retrofitting by leveraging their intrinsic shape memory effect (SME) to generate pre-stress through non-destructive thermal activation. While offering superior advantages over passive repair methods, the long-term effectiveness of SMA-based retrofitting critically hinges on the retention of recovery stress under cyclic fatigue loading. However, the degradation mechanisms governing recovery stress under combined phase transformation and fatigue remain poorly quantified, impeding the optimization of SMA applications in engineering practice.

Objective

This study systematically investigates the fatigue-induced degradation of recovery stress in Nickel-Titanium (NiTi) SMAs under high-stress cyclic loading, aiming to unravel the interplay between macroscopic mechanical behavior and microstructural evolution.

Method

A multi-scale experimental framework integrates macroscopic mechanical testing (high-stress cyclic loading at five stress levels) with microscopic fracture analysis (scanning electron microscopy). Empirical relationships between stress amplitude and fatigue life (Ni) / recovery stress loss rate (RSLR) are established, while crack propagation modes are quantitatively correlated to stress amplitudes.

Results

Fatigue life and deformation increments exhibit inverse proportionality to applied stress amplitude. Concurrently, experimental findings identify a critical yield stress threshold (385 MPa) that governs recovery stress degradation. Below this threshold, RSLR remains negligible (2.13 × 10–5 MPa/cycle), preserving > 96% of initial recovery stress after 742,229 cycles. Above this threshold, transverse crack propagation leads to an accelerated degradation of the recovery stress.

Conclusion

The identified yield stress threshold and empirical models provide a mechanistic foundation for designing fatigue resistant SMA retrofitting systems. By linking macro-mechanical degradation to microstructural crack evolution, this work advances the predictive capability for recovery stress retention, enabling optimized SMA deployment in critical infrastructure under high-stress service conditions.