Wire Stress Research Articles

A new concept of structural smart fabric activated by shape memory alloys

Abstract This work presents the development, prototyping and validation of a new concept of structure called structural smart fabric (SSF). An SSF is a chainmail fabric composed by interconnected elements, called cells, which can be stiffened by reactive elements, such as those made by shape memory alloy (SMA). Exploiting the shape memory functionality, SSFs are capable of sensing and reacting to external stimuli. Based on this concept, in this study we propose an SSF that integrates SMA wires into a 3D-printed chainmail structure. The shape memory effect of these wires is used as an actuating mechanism that, at high temperature, tightens the adjacent cells together and provides increased structural stiffness. In this study, finite element simulations were initially conducted to enhance the comprehension of the SSF’s mechanical behaviour. The influence of the initial cell spacing on the SSF stiffness and the wire stress profiles was evaluated during bending loading, as well as the evolution of contact pressure profiles between adjacent cells. This numerical approach enabled to tune the design of the SSF prototypes which were successively manufactured using selective laser sintering additive manufacturing technology with PA12. After the integration with the SMA wires, the SSF prototypes were tested under a 3-point bending configuration at different temperatures. The results revealed a remarkable increase in structural stiffness at elevated temperatures compared to ambient conditions. This study set the basis for a deeper understanding of SSF’s unique capabilities and potential applications in fields where adaptive and responsive structures are required.

Evaluation of Electrochemical Properties and Life Prediction of Sensor Wire in Leak Detection Systems of Underground Heating Pipelines

In this study, we investigated the electrochemical properties and lifespan of the NiCr (NiCr 8020) sensor wire of a resistance leaking detection (LD) system to detect pipe corrosion and leakage in an actual district heating (DH) system. The temperature and applied stress of the sensor wire during the actual operation of the resistance LD system of the DH system were derived through simulations and calculations. The anodic dissolution of the sensor wire was accelerated with the increased temperature and the applied current. The corrosion type changed from localized corrosion, such as pitting, to uniform corrosion. The applied stress caused ductile fracture of the thinned sensor wire by anodic dissolution. In conclusion, we confirmed that in the resistance LD system of a DH system, where current and stress are applied at high temperatures, the sensor wire becomes thin due to the anodic dissolution and subsequent ductile fracture. In addition, the lifespan of the sensor wire was derived according to the resistance level measured in the resistance LD system of the DH system. Our findings contribute to preventing failure and improving the reliability of the resistance LD systems of DH systems.

A data-driven model for predicting fatigue performance of high-strength steel wires based on optimized XGBOOST

Fatigue damage to high-strength steel wires in cable-stayed bridges can significantly compromise bridge reliability. Previous studies have primarily focused on isolated factors such as corrosion rate or stress ratio, failing to capture the complex interactions among multiple variables. Consequently, a few researchers have developed data-driven models using machine learning methods. However, these unoptimized models exhibit limited prediction performance and convergence speed, and lack in-depth analysis of feature effects on the models. To address these shortcomings, this study combines the Gray Wolf Optimization (GWO) algorithm with the XGBoost model to create a data-driven approach for predicting the fatigue performance of high-strength steel wires under multiple influencing factors. The model is validated using both journal and experimental datasets. Results demonstrate that the proposed GWO-XGBoost model achieves high prediction accuracy (R2 = 0.94) and strong generalization ability, and exhibits rapid convergence in optimizing hyperparameters, outperforming BP neural networks and ridge regression models. Additionally, the study highlights the primary effects of wire mass loss, stress range, and average stress on fatigue life prediction, emphasizing the importance of preventing corrosion and managing stress levels to enhance wire fatigue performance. Analysis of model parameters reveals that alpha and colsample_bytree are critical for maintaining model stability and minimizing error rates, while maximum depth and learning rate significantly impact model complexity and convergence. This suggests that proper tuning of these parameters is essential for ensuring model robustness, efficiency, and generalization ability.

Recoverable and plastic strains generated by forward and reverse martensitic transformations under external stress in NiTi SMA wires

Although superelastic NiTi shape memory alloy wire displays very high resistance to plastic deformation in austenite and martensite phases, incremental plastic strains are recorded whenever the cubic to monoclinic martensitic transformation (MT) proceeds under external stress leading to functional fatigue degradation. Therefore, special closed-loop thermomechanical loading tests were performed to shed light on the mechanism by which the incremental plastic strain are generated. These tests revealed that both forward and reverse MTs occurring above certain stress thresholds generate plastic strains specific for the [temperature, stress] conditions under which the MTs occurred. While the forward MT upon cooling does not produce plastic strain or permanent lattice defects up to 500 MPa stress, the reverse MT upon heating starts to generate them from 100 MPa. While plastic strain generated by the forward MT merely elongates the wire, plastic strain generated by the reverse MT also reduces the recoverable strain. Since the reverse MT upon heating generates plastic strains at lower external stresses than the forward MT upon cooling, it is largely responsible for cyclic instability of NiTi actuators. The characteristic thresholds and magnitudes of plastic strains generated by the forward and reverse MTs define the functional fatigue limits for specific NiTi wires.

Development of corrosion-fatigue analysis method of cable hangers in tied-arch bridges considering train-bridge interaction

This study proposes an integrated corrosion-fatigue analysis method for bridge hangers by combining the dynamic bridge-train interaction analysis for random train arrivals with various speeds and the linear elastic fracture mechanics (LEFM)-based crack propagation analysis considering the corrosion-fatigue effects. Accordingly, a three-stage process, namely, zinc coating corrosion, pit-crack transition, and corrosion-fatigue crack propagation for wires in hangers, was proposed to simulate the total service life. A train-bridge-interaction analysis was conducted on a tied-arch bridge with multiple cable hangers using the vector form intrinsic finite element method, where the stresses in the hangers were generated under high-speed train loads. The pit-crack transition was analyzed based on the pit growth and fatigue growth; whose rates compete to dominate the transition phenomenon. The fatigue crack growth rate was estimated using a LEFM approach considering the equivalent stress ranges and number of stress cycles. The effects of reducing the cable cross-section and updating the internal stress of the multi-layered wires were investigated. The present method was compared with the continuum damage mechanics model for validation. A relatively short remaining corrosion-fatigue life was found in the cables under the train loads, after corrosion of the zinc coating and pit-crack transition in the steel wires were developed.

Fatigue life prediction of corroded hangers with parallel steel wire in a network arch bridge under vehicle-bridge interaction based on a novel noniterative simplified method

Fatigue damage is a main concern during the life-cycle maintenance of bridges with corroded hangers under vehicle-bridge interaction (VBI). In this study, a novel noniterative simplified method for VBI is proposed to analyze the responses of hangers in a network arch bridge, considering the effects of vehicle types, driving lanes, and road surface roughness. Furthermore, the fatigue life of corroded hangers is investigated, considering the actual traffic flow and uneven distribution of stress in the hanger’s cross-section. The results show that longitudinal and transverse bending moments of the hanger significantly affect the stress of steel wires in one hanger but have limited influence on stress amplitudes. The fatigue lives of steel wires are considerably reduced when subjected to both uniform and pitting corrosion. The fatigue life of steel wires is reduced under deteriorating road surface conditions. Moreover, as the fatigue life of steel wires in the hangers declines, the variations in fatigue life among individual steel wires within a single hanger gradually decrease. Consequently, this trend leads to a heightened likelihood of continuous wire breakage.

Multiphysics modeling and optimization of an innovative shape memory alloy-polymer active composite

Shape memory alloys (SMAs) are a unique class of smart materials capable of recovering significant deformations through temperature variations, making them attractive for adaptive structures and morphing applications. However, integrating SMAs into polymer composites poses significant challenges, such as interfacial delamination and matrix overheating during thermal activation, in addition predicting the stress acting on the SMA during the actuation is pivotal. Addressing these issues is crucial for realizing the full potential of SMA-based active composites in aerospace, automotive, and renewable energy sectors. This study presents a novel multi-material design strategy for SMA-polymer active composites, featuring a rigid PC/ABS layer for mechanical integrity, a soft high-temperature silicone coating for encapsulating SMA wires, and aluminum terminals for wire crimping. A comprehensive multiphysics FEM model was developed to accurately capture the coupled thermo-mechanical response. Extensive experimental characterization and validation were conducted, followed by systematic parametric studies to investigate the effects of critical design parameters on key performance metrics. The developed prototype exhibited remarkable shape morphing capabilities, with a maximum tip deflection of 68 mm (deflection-to-length ratio of 0.4). Excellent agreement between experiments and simulations was achieved, with a maximum error of 1.7 % in tip deflection, validating the accuracy of the multiphysics model. Parametric analyses quantified the trade-offs between geometric parameters, revealing their influence on activation temperature, deflection, SMA wire stress, and fatigue life. Optimal configurations enabling low activation temperatures (<150 °C), low stress levels (<400 MPa), and high predicted fatigue life (>50,000 cycles) were identified. The multi-material design approach effectively addressed common issues in SMA-polymer composites, enabling reliable actuation cycles without damage accumulation. The validated multiphysics model and parametric insights provide a comprehensive framework for optimizing the design and performance of SMA-polymer active composites, paving the way for their widespread adoption in shape morphing applications. Potential implications include the development of adaptive aerodynamic surfaces, deployable structures, and energy-efficient systems across various industries.

Finite element modeling for single-twisted Fi(29) strand that reproduces strand stiffness and wire stress

Finite element modeling for single-twisted Fi(29) strand that reproduces strand stiffness and wire stress

Development and characterization of thin iron-based shape memory alloy prestressing wire

Iron-based shape memory alloys (Fe-SMA) have been used successfully in the previous years as prestressing reinforcement in the form of rebars, rods and flat strips, for various types of structural elements and loading scenarios. This paper introduces a new application of this material in the form of thin wire. An experimental characterization study is presented herein for Fe-SMA wire that was drawn to a diameter of 0.5 mm, regarding its tensile stress-strain response and recovery stress development upon heating, for different activation temperatures and prestraining levels. Furthermore, an investigation is presented regarding the effects of heat treatment conditions on the mechanical response and prestressing performance of the wire. For the optimum heat treatment conditions and activation temperature range considered in this study, the measured tensile strength and recovery stress of the Fe-SMA wire was 1117 MPa and up to 390 MPa, respectively. The results indicate a strong potential of Fe-SMA as a candidate prestressing material where flexible wire cross-sections of small diameter are desired instead of larger, solid cross-section tendons (e.g., multi-strand wire ropes or concrete confinement spirals), or as novel short fiber reinforcement for concrete with prestressing capabilities.

Candy box technique for the fixation of inferior pole patellar fractures: finite element analysis and biomechanical experiments

BackgroundMaintaining effective reduction and firm fixation in inferior pole patellar fractures is a highly challenging task. There are various treatment methods available; although tension-band wiring combined with cerclage wiring (TBWC) is the mainstream approach, its effectiveness is limited. Herein, we propose and evaluate a new technique called candy box (CB), based on separate vertical wiring (SVW), for the treatment of inferior pole patellar fractures. Specifically, we provide biomechanical evidence for its clinical application.MethodsFive fixation models were built: SVW combined with cerclage wiring (SVWC); TBWC; modified SVW with the middle (MSVW-A) or upper (MSVW-B) 1/3 of the steel wire reserved, and CB. A finite element analysis was performed to compare the displacement and stress under 100-N, 200-N, 300-N, 400-N and 500-N force loads. Three-dimensional printing technology was utilized to create fracture models, and the average displacement of each model group was compared under a 500-N force.ResultsThe results of the finite element analysis indicate that CB technology exhibits significantly lower maximum displacement, bone stress, and wire stress compared to that with other technologies under different loads. Additionally, in biomechanical experiments, the average force displacement in the CB group was significantly smaller than that with other methods under a 500-N force (P < 0.05).ConclusionsCB technology has the potential to overcome the limitations of current techniques due to its superior biomechanical characteristics. By incorporating early functional exercise and ensuring strong internal fixation, patient prognosis could be enhanced. However, further clinical trials are needed to fully evaluate the therapeutic effects of CB technology.

Influence of coiling behavior on axial stress in steel wires of submarine power cables: A numerical study

Coiling processes that are commonly employed to lay submarine power cables to static tanks on ships cause twisting and bending deformations of the cables, potentially affecting the integrity and safety. This study investigates the mechanical behavior of submarine power cables subjected to combined torsional and bending loads using analytical models and finite element method-based software. The objective of the numerical analysis was to evaluate compressive stresses generated within the armor wires of submarine power cables. Additionally, the investigation was extended to assess the potential risk of wire buckling, i.e., bird-caging. The influence of wire pitch length and tank diameter on the magnitude of compressive stress was examined, and the findings revealed a decrease in the likelihood of wire buckling with longer pitch lengths and larger tank diameters. The results of this study will offer valuable insights into the cross-sectional design and the mechanical behavior of submarine power cables subjected to coiling operation.

DESIGN OF UNDIRECT GUY WIRE TENSION METER BASED ON STRAIN GAUGE

The safety of the tower is depend the tension of guy wire, where it must have the same tensile stress at all positions. To meet this requirement, the load cell guy wire is designed based on strain gauge. Load cell guy wire is designed portable and it can detect stress of the guy wire indirectly. The main component of load cell is a beam, two hooks and a cylinder to form a bending moment force in the beam, the value of the bending moment on the beam will be directly proportional to the increase or decrease in force drag on guy wire. Design process of load cell doone using mathematical analysis, and then the load cell is calibrated by standard load cell, based on the data result of calibration is known that the stress at the guy wire load cell is close and under the yield stress of the load cell material, it is proved that load guy wire cell’s design result is safe to use.

Multi-field coupled dynamics for a movable tooth drive system integrated with shape memory alloys

The harmonic movable tooth drive system integrated with shape memory alloys has a small size and a large output torque. Its dynamics performance is the key factor for evaluating the drive system. Here, for the drive system, based on its structure and working principle, the coupled dynamics equations are deduced. Using the equations, changes of the natural frequencies of the drive system during the operation are investigated. Effects of the system parameters and SMA wires phase change process on the natural frequencies are analyzed. The nonlinear resonant frequencies of the drive system and its amplitude-frequency relationship are studied. Results show that natural frequencies of the drive system change periodically which is caused by SMA phase transformation during operation. The eccentricity, movable tooth radius, the wave generator radius and SMA wire length have also important effects on the natural frequencies of the drive system. The nonlinear resonant frequencies are smaller than linear resonant frequencies. In the design of the drive system, the coupled nonlinear effects of the temperature, phase change, stress and strain of the SMA wires, and the system parameters of the movable tooth drive system should be considered. In this paper, the coupled nonlinear dynamics model of the harmonic movable tooth drive system integrated with shape memory alloys is proposed in which the coupled effects of the temperature, phase change, stress and strain of the SMA, and the system parameters of the movable tooth drive system are considered.

Explorations of knitted shape memory alloy actuation behavior under high loads via finite element analyses and experimental studies

The properties of shape memory alloy (SMA) wires have long been leveraged across a variety of industries. While the response of such SMA forms implemented as straight axial actuators is well understood, curved and complex configurations such as knits have received far less attention. Considering 2D configurations, it is well known that knits exhibit more in-plane compliance than weaves and meshes, the curved wires comprising the former being much more flexible than the straight wire segments in the latter. In addition, knitted structures are uniquely highly tailorable. Knitting techniques and patterns developed in the textile industry allow for variable materials and geometries in the same structure, allowing for a large range of tailored macro-structure responses. Existing efforts to model the behavior of knitted SMA structures are lacking; though finite element analysis (FEA) models have been presented for knit SMAs, these models either only consider superelastic SMA behavior, or, in those that account for actuation behavior, the applied load conditions studied are insufficient to fully leverage the thermally induced strain recoverability of SMAs. This work seeks to develop and validate a finite element model for the actuation of SMA knitted structures where individual SMA wire components are axially stressed to more than 100 MPa. A representative volume element is developed for a common knit pattern, and macro-structure responses are explored and compared with experiments. This research provides a foundation for better understanding fundamental capabilities and responses of knitted SMA structures, allowing for better design, functionality, and customizability of the applications into which they are incorporated, enabling development of unique soft actuators. A shape-set sample examined herein generated 13% extension (analogous to strain) and recovered more that 6% under a load associated with 100 MPa stress in a straight wire, and a sample knit off-the-spool generated over 20% extension and recovered 9% for the same load.

Degradation of I c due to residual stress in high-performance Nb3Sn wires submitted to compressive transverse force

Future particle colliders in search for new physics at the energy frontier require the development of accelerator magnets capable of producing fields well beyond those attainable with Nb-Ti. As the next generation of high-field accelerator magnets is presently planned to be based on Nb3Sn, it becomes crucial to establish precisely the mechanical limits at which this brittle and strain sensitive superconductor can operate safely. This paper reports on the stress dependence and the permanent reduction of the critical current under transverse compressive loads up to 240 MPa in state-of-the-art restacked-rod-process (RRP®) and powder-in-tube Nb3Sn wires. Single-wire experiments were performed at 4.2 K in magnetic fields ranging between 16 T and 19 T on resin-impregnated samples to imitate the operating conditions of a wire in the Rutherford cable of an accelerator magnet. Depending on the wire technology, we measured irreversible stress limit values—defined as the transverse stress value, leading to a permanent reduction in the critical current of 5%, assessed by convention at 19 T—ranging between 110 MPa and 175 MPa. This permanent reduction of the critical current after mechanical unload can occur for two reasons, which can be concomitant: the plastic deformation of the Cu matrix that produces residual stresses on the Nb3Sn lattice and the formation of cracks. We developed a method to identify the dominant degradation mechanism in our experiments that allowed us to predict the fraction of critical current lost due to residual stresses. Interestingly, we found that in the RRP® wires the measured reduction of Ic after unload from stresses as high as 240 MPa can be fully ascribed to residual stresses. An independent confirmation of this conclusion coming from a study combining x-ray tomography and deep learning Convolutional Neural Networks is also reported.

Armored steel wire stress monitoring strategy of a flexible hose in LNG tandem offloading operation

Cryogenic flexible hose is the key equipment for tandem offloading operation of Floating Liquefied Natural Gas (FLNG). The harsh marine environment leads hulls motion responses and complex hose motion characteristics during the tandem offloading, thus causing various failure behaviors of the entire hose. In this paper, a combined global-local monitoring strategy for armored steel wire stress distributions in cryogenic flexible hose is proposed. High-precision flexible hose governing equations are established by using the function to fit the relationship between the vertical force and the hose length. A reasonable monitoring strategy is given based on the pipeline configuration variations and sensor accuracy. Real-time monitoring of the flexible hose from the global (hose) to the local (armored steel wire) during the tandem offloading is carried out by installing sensors in specified locations on hulls and hose segments. The tandem offloading operation under different (static, calm and harsh) sea states is modelled by Orcaflex software. An armored steel wire model is developed using ABAQUS software. Comparisons of the pipeline configurations, curvatures, axial forces and maximum wire stresses are made with the simulation results to verify the feasibility of the monitoring strategy. The results show that the proposed monitoring strategy in this paper can accurately and effectively obtain the hose motion characteristics and maximum stress states of armored steel wires under different sea states, and can evaluate the hose structural safety in real time during the tandem offloading operation.

Experimental study on flexural behavior of RC beams strengthened with FRP/SMA composites

Fiber reinforced polymer (FRP)/shape memory alloy (SMA) composites are disclosed that can be used to repair cracked members and improve the mechanical behavior of concrete structures. This work aims to synthetically investigate the flexural behavior of reinforced concrete (RC) beams strengthened with FRP/SMA composites through both experimental study and finite element analysis. Five beam specimens are prepared to investigate the effect of important parameters on the flexural behavior of RC beams strengthened with FRP/SMA composites, including the different strengthened materials (i.e., SMA wires, CFRP sheets, and FRP/SMA composites) and different types of FRP/SMA composites (i.e., CFRP/SMA composites and BFRP/SMA composites). The test results showed that the flexural stiffness and capacity improvement of the beam strengthened with only SMA wires were not significant, but the ductility was not reduced. The flexural capacity of the beam strengthened with CFRP sheets was effectively improved, but the stiffness improvement was limited. However, the flexural stiffness and capacity of the beam strengthened with FRP/SMA composites significantly increased. At the same time, the service performance was also improved, FRP/SMA composites could effectively reduce the strain of longitudinal rebars and constrain crack development. Compared to the control beam, the capacity of the beam strengthened with the FRP/SMA composites improved from 17.52% to 40.23%, and the stiffness improved from 9.95% to 17.65%. In addition, the CFRP/SMA composites could more effectively improve the capacity and stiffness of strengthened beams than the BFRP/SMA composites because of the higher elastic modulus of CFRP sheets. The strength of BFRP sheets of the BFRP/SMA composites can be fully utilized after reinforcement. Finally, an iterative method for calculating the recovery stress of SMA wires for reinforcement was proposed and incorporated with finite element method for simulation, which was verified by experimental results.

Impact of hardening law on the FEM prediction of residual stresses in copper-clad aluminum wires

Impact of hardening law on the FEM prediction of residual stresses in copper-clad aluminum wires

A modified separate vertical fixation by wires and titanium cables for comminuted inferior patella fracture: A technique note and finite element analysis

PurposeComminuted inferior patellar pole fractures are challenging injuries and require adequate treatment due to the extension mechanism of the knee. MethodsA modified separate vertical fixation by wires and Titanium cables was established according to a finite element biomechanical study. Between September 2018 and May 2021, 18 patients with inferior pole fractures of the patella were retrospectively enrolled in this study. ResultsThe results of the finite element analysis showed the concentration of stress in the intermediate vertical wire and the cerclage wire. As a partial replacement for steel wires, Titanium cables provide less concentration of stress on the vertical wire (489.4 MPa vs 441.2 Mpa) and less cutting force on the bone (75.87 Mpa vs 53.27), which reduces the possibility of internal fixation failure and improves the stability of internal fixation. In the clinic study, No patients experienced non-union of the fracture, loss of fracture repositioning, malunion of wounds, or wire breakage. At the last follow-up, the average range of motion was 134.7°±11.2°, and the Lysholm Score was 90.7 ± 3.9. ConclusionsThe separate vertical fixation by wires and titanium cables is an effective fixation method for treating displaced, comminuted inferior pole fractures, which attributes to early exercise and better function.

Digital Image Correlation for Measuring Full-Field Residual Stresses in Wire and Arc Additive Manufactured Components

This study aims to demonstrate the capability of the digital image correlation (DIC) technique for evaluating full-field residual stresses in wire and arc additive manufactured (WAAM) components. Investigations were carried out on WAAM steel parts (wall deposited on a substrate) with two different wall heights: 24 mm and 48 mm. Mild steel solid wire AWS ER70S-6 was used to print WAAM walls on substrates that were rigidly clamped to H-profiles. DIC was used to monitor the bending deformation of WAAM parts during unclamping from the H-profiles, and residual stresses were calculated from the strain field captured during unclamping. Residual stresses determined from the proposed DIC-based method were verified with an analytical model and validated by the results from established residual stress measurement techniques, i.e., the contour method and X-ray diffraction.