Varying Load Conditions Research Articles

Engine Performance and Emission Evaluation of Gasoline-Ethanol Fuel Blend in SI Engines Under Various Conditions of Load and Speed

Ethanol fuel is considered a renewable energy source with a lower global warming potential than gasoline. The purpose of this paper is to analyze the emissions and performance of gasoline-ethanol blends in SI engines under various conditions. A computerized 4s, 1cyl, VCR spark ignition engine is used for the tests to measure the performance of Gasoline-Ethanol (GE) blends in particular E-10 (10% ethanol, 90% gasoline). For measuring exhaust emissions as well as performance, regular gasoline fuel is used for the additional tests. Engine performance using ethanol-gasoline blended fuel has been evaluated at different working conditions: 1200–1800 rpm, AFR 0.9, STs 300, CR10:1. When vehicles running on ethanol-gasoline blend indicated a decrease in the amounts of HC, NOx, and CO exhaust gases while 3.9% increase in CO2 emissions as compared to unleaded gasoline fuel. Furthermore, it has been shown that the brake power, torque, specific fuel consumption increases when a Gasoline-Ethanol (GE) blend is used over regular gasoline fuel.

Generative adversarial networks for stack voltage degradation and RUL estimation in PEMFCs under static and dynamic loads

Accurately predicting the degradation and remaining useful life (RUL) of Proton Exchange Membrane Fuel Cells (PEMFCs) is crucial for enhancing their reliability, particularly in automotive and energy sectors. Traditional models often fail to capture the complex, non-linear degradation patterns of PEMFCs, resulting in suboptimal predictions. This study addresses these technological gaps by introducing a novel approach, the Self-Attention Temporal Dual Discriminator Generative Adversarial Network (SAT-DD-GAN). This model is designed to overcome the limitations of existing methods by integrating advanced Long Short-Term Memory (LSTM) networks for time-series analysis, a self-attention mechanism to focus on critical degradation signals, and dual discriminators to improve prediction accuracy and robustness. By addressing the gap in handling long-term dependencies and complex degradation patterns, the proposed SAT-DD-GAN bridges the disconnect between traditional models and the real-world degradation behavior of PEMFCs. The SAT-DD-GAN achieved groundbreaking predictive performance, with the lowest RMSE (0.983E-3 for static load, 1.012E-3 for dynamic load), MAPE (0.036E-1 and 0.253E-1), MAE (0.776E-3 and 0.806E-3), and the highest R2-score (0.9998 and 0.9983), alongside zero relative error for both datasets. These results demonstrate the model's ability to capture the intricate degradation dynamics more effectively than existing state-of-the-art methods. By filling the technology gap of accurately modeling PEMFC degradation under varying load conditions, this study establishes a new standard for PEMFC prognostics and paves the way for future innovations in optimizing fuel cell performance and longevity.

Advanced Design and Implementation of a 2-Channel, Multi-Functional Therapeutic Electrical Stimulator

This research introduces the design, implementation, and rigorous evaluation of a novel 2-channel, multi-functional therapeutic electrical stimulator, meticulously engineered to meet the stringent demands of contemporary clinical applications. The device integrates a high-speed R-2R ladder DAC and a sophisticated pulse generator unit, capable of producing twelve essential current waveforms with fully adjustable parameters, including pulse amplitude, pulse duration, and pulse repetitive frequency. The proposed driving stage unit ensures precise voltage-to-current conversion, delivering stable and accurate output currents even under varying load conditions, which effectively simulate the diverse impedance characteristics of human tissue. Extensive testing confirmed the compliance with international medical standards, notably IEC 60601-1, IEC 60601-1-2, and IEC 60601-2-10. The experimental results underscore the device’s consistent operation within prescribed safety and performance thresholds, with all deviations in pulse parameters remaining well below the permissible limits. Furthermore, the proposed electrical stimulator demonstrated exceptional stability across variable load conditions, as evidenced by minimal amplitude errors and high correlation between waveform characteristics. These findings highlight the proposed device’s robustness and its potential as a versatile tool for a wide range of therapeutic applications, including pain management, muscle stimulation, and nerve rehabilitation, thus marking a significant advancement in the field of therapeutic electrical stimulation.

X-ray micro-computed tomography for mechanical behaviour analysis of Automated Fiber Placement (AFP) laminates with integrated gaps and overlaps

Automated Fiber Placement (AFP) is a manufacturing technique widely used for the serial production of aerospace parts. A deep understanding of the effect of lay-up defects is crucial for part and lay-up design. Currently, numerical models for structural simulation lack a precise representation of the internal structure of AFP laminates, which is crucial for understanding the impact of defects on mechanical properties. This paper presents a novel approach based on high-resolution micro-computed tomography (micro-CT) scans from specimens manufactured with AFP, which automatically creates a mesoscale numerical model incorporating as-fabricated defect morphologies. The hexahedral mesh, generated from the segmented plies of the micro-CT volume, accounts for ply thickness and out-of-plane fiber orientation. This approach is verified with mechanical testing and digital image correlation (DIC) under tensile loading. The simulation results align closely with experimental testing and accurately illustrate the influence of fiber waviness in various defect configurations, such as gaps and overlaps. The study shows that lay-up defects can lead to knockdown factors of up to 12% in tensile properties, with each defect creating a distinct pattern in the local strain. This model can serve as a benchmark for further numerical simulations and surrogate models of defect configurations under varying loading conditions.

Research on the Energy Management Strategy of a Hybrid Tractor OS-ECVT Based on a Dynamic Programming Algorithm

The multi-degree-of-freedom characteristics of the planetary gear electronic continuously variable transmission (ECVT) configuration in series-parallel hybrid tractors impose more complex requirements for energy management strategies under variable load conditions. For a high-power hybrid tractor, this paper takes the hybrid tractor output-split (OS)-ECVT configuration as the research object and describes the principles of stepless transmission and power-splitting within the configuration. In order to improve the fuel economy of high-power hybrid tractors and the running status of power components, an energy management strategy focused on ploughing conditions based on the Bellman minimum dynamic programming (DP) algorithm is proposed in this paper. Second, equivalent fuel consumption is selected as the performance index for energy-saving control, and the solving principle of the energy management strategy based on the dynamic programming algorithm is established to facilitate the resolution process of the energy management strategy. Finally, the energy-saving control simulation is completed under ploughing conditions. The results show that compared with the energy management strategy based on the optimal operating line (OOL), the energy management strategy based on DP fully utilizes the benefits of low-cost electric energy and enables the hybrid power system to have a wider range of stepless transmission performance. In addition, the hybrid power system has the advantages of enhanced decoupling of speed and torque, higher efficiency, and more economical secondary energy conversion. As a result, the whole machine has enhanced power-split performance, greatly improving the running conditions of the power components. The equivalent fuel consumption values of the energy management strategies based on DP and OOL are about 3.1238 L and 4.2713 L, respectively. The equivalent fuel consumption based on DP is reduced by about 26.87%, which effectively improves the fuel efficiency of hybrid tractors.

Influences of the normal loading condition and surface texture on interface shear behavior between sand and suction caisson wall

The mechanical behavior of the interface between soil and the suction caisson wall determines the installation behavior and bearing capacity. A series of interfacial shear tests are conducted to study the effects of the normal loading condition and the interface texture on the sand-suction caisson interface shear characteristics. The relative density of the sand used in the test is 0.9. It is found that with the increase of shear displacement, the shear stress-displacement curve under a constant normal load condition (CNL) has an obvious strain-softening trend. On the contrary, the shear stress increases linearly with increasing the shear displacement under a variable normal load condition (VNL). The stress ratio between shear and normal stress, the broken zone thickness, and the shear deformation zone thickness for a convex suction caisson wall-sand interface are significantly larger than those of the grooved interface. However, when the roughness increases to a certain value, the stress ratio between shear and normal stress would decrease. Under large displacement shearing, the degree of sand particle breakage becomes significantly higher than that under small displacement shearing. These results help understand the shear characteristics of the sand-suction caisson wall and invent the new type of the suction caisson.

Design, Simulation, and Fabrication of Composite Lattice Orthoses with Enhanced Structural Performance

Abstract Orthoses play a critical role in rehabilitation by providing fracture stabilization, external load protection, and deformity correction. Traditional methods of orthotic manufacturing often result in reduced breathability leading to potential skin problems, and increased bulkiness and weight due to material and processing limitations. Method: This study aims to enhance breathability and structural performance of orthoses through the utilization of a fiber-reinforced composite lattice design fabricated using a Coreless Filament Winding (CFW) process. An arm brace was designed and manufactured, which incorporates four modules made of fiberglass/polystyrene composite lattices assembled together using adjustable thermoplastic connectors. To simulate the structural performance, a Finite Element Model (FEM) was constructed with careful consideration of the interactions between the connectors and the lattice modules, and this was subsequently validated through experiment. Results: In comparison to a benchmark brace made of Polylactic Acid (PLA) lattice, the composite brace exhibits a significant reduction in thickness (60%) and weight (44%) while maintaining equivalent structural performance. The validation test indicates the FEM's reliability in predicting structural stiffness and strength, with the predicted peak loading being slightly conservative (5%) compared to experimental results. Conclusion: Composite lattice structures represent a significant advancement in the design of breathable, lightweight, and high-strength orthoses. Moreover, the developed FEM serves as a valuable tool for accurately predicting structural performance and optimizing orthotic design under varying loading conditions.

Plasticity analysis and a homogenized constitutive model of compressible multi-layer structure of battery

A homogenized constitutive model for the compressible multi-layer structure of battery (CMLSB) under external loading is essential for optimizing the structural design of electric assemblies. Currently, there is no specific constitutive model that is both mechanically explanatory and operationally applicable to CMLSB under varied loading conditions. In this study, due to limited understanding of the in-plane behavior of CMLSB, an analytical model was developed to investigate plasticity in this specific direction using the strain probing method. The observed plastic characteristics inspired the formulation of a novel two-dimensional constitutive framework for CMLSB in the in-plane direction.By integrating this new constitutive framework with one-dimensional plastic descriptions, a hybrid constitutive model was introduced and implemented in finite element software. Calibration and validation of the model were performed using a commercial pouch cell battery and its segments under various loading conditions. Finite element simulations with the hybrid model demonstrated remarkable accuracy in predicting the mechanical behavior of the cell under various in-plane and out-of-plane compression scenarios. Additionally, simulations were carried out to analyze the impact of cell packaging and air pressure. The new hybrid battery model is considered a user-friendly, physically interpretable, and high-fidelity tool, poised to significantly facilitate the comprehensive design of electric devices.

Adaptive fast terminal sliding mode control of robotic manipulators based on joint torque estimation and friction compensation

AbstractIn this work, an adaptive fast terminal sliding mode control (AFSMC) approach based on joint torque estimation and friction compensation is proposed to enhance the trajectory tracking accuracy of robotic manipulators under variable load conditions. The joint torque estimation utilizes an improved harmonic drive compliance model and adaptive low‐pass filtering, and friction compensation employs a hybrid model accounting for velocity and load torque effects. These compensations reduce the upper bound of the uncertainty, while AFSMC further reduces dependency on upper uncertainty bounds and minimizes the chattering. The stability analysis using the Lyapunov method confirms the effectiveness of this approach. Experimental results demonstrate that the proposed controller achieves smaller root mean square and maximum error of trajectory tracking, thus significantly improving trajectory tracking accuracy under variable load conditions.

Effect of strain ratio and pre-strain on the low-cycle fatigue behavior of 4130X steel at different strain amplitudes

This study investigates the impacts of strain ratio and pre-strain on the low-cycle fatigue properties and microscopic damage mechanisms of 4130X steel across varying strain amplitudes. Under symmetric loading, initial cycles at low strain amplitudes demonstrate clear peak/valley stress hardening followed by cyclic softening in later stages of fatigue. In contrast, the hardening behavior vanishes at higher strain amplitudes. Increasing strain ratio and pre-strain cause the initial hardening behavior at low strain amplitudes to gradually disappear. Additionally, at lower strain amplitudes, fatigue life decreases as strain ratio and pre-strain rise, attributed to substantial tensile mean stress. Microscopic examination reveals that symmetric cyclic loading at low strain amplitudes releases stress concentrations caused by quenched and tempered processing and reduces both dislocation density and localized plastic strain. Conversely, at higher strain ratios and pre-strains, increased tensile mean stresses not only intensify dislocation multiplication, resulting in high dislocation density, but also activate multi-slip system, leading to dislocation cross-slip. Moreover, at a high strain amplitude of 0.45 %, pre-strain aids in martensite recovery and promotes dislocation annihilation during recovery, thus inducing cyclic softening. Finally, the fatigue lives under varied loading conditions are compared with the fatigue design curve prescribed by ASME VIII-II code.

Experimental study on single-cylinder two-stroke piston expander based on in-cylinder spray heat transfer

Compressed air energy storage stands as a highly promising technology within the realm of energy retention. The piston expander finds applicability in smaller-scale compressed air energy storage systems. In compressed air energy storage systems, the expansion process is critical in energy discharge and significantly impacts overall performance. Isothermal expansion techniques are effective in enhancing the operational efficiency of piston expanders, in contrast to adiabatic expansion methodologies. Previous simulations by our research group show that the isothermal expansion model has a lower power output than the adiabatic expansion model due to its higher exhaust pressure. To further validate the accuracy of the simulation results, an experimental platform was constructed and the uncertainty of the experimental system as well as the measured data was evaluated. This study conducted experimental research using the single-variable method, focusing on different load conditions and spray parameters. The study findings indicate that the exhaust pressure during isothermal expansion consistently exceeds that of adiabatic expansion. The exhaust pressure of isothermal expansion increased by 3.85 % to 14.9 %. Under varying load conditions, the average rotational speed and output power of isothermal expansion were noted to be inferior to those of adiabatic expansion. Despite changes in nozzle diameter or spray temperature when the spray timing is set at 0°-180°, the average rotational speed and output power of isothermal expansion remain lower than that of adiabatic expansion. The average output power of isothermal expansion decreased by 1.29 % to 5.24 %. Nevertheless, if the spray timing is set between 0°-120°, the average output power of the isothermal expansion surpasses the adiabatic expansion with an improvement of 1.84 %.

High-temperature fretting wear behavior and microstructure stability of a laser-cladding Ti-Al-C-N composite coating meditated by variable cycle conditions

Ti-6Al-4 V titanium alloy is used for low-pressure compressor blades of aero-engine due to its high specific strength, excellent corrosion resistance and high-temperature stability. Low-pressure compressor blades are subject to fretting wear in service, which may lead to fracture failure of the blades. The preparation of wear-resistant coatings is currently an effective solution in solving the problem of fretting wear on Ti-6Al-4 V titanium alloy. However, the fretting wear resistance and microstructure stability of the coating under variable cycle fretting conditions require more attention. In this work, the fretting wear performance and microstructure stability of the Ti-Al-C-N composite coating under variable cycle fretting conditions are investigated. The results show that the parameters of variable cycle operating conditions have a notable effect on the coefficient of friction (COF). The variable frequency and variable temperature working conditions result in the alteration of the fretting operation mechanism. Whereas the variable stroke amplitude and the variable load conditions do not cause changes in the fretting operation mechanism, and both are in the gross slip region (GSR). The lowest wear rate occurs under variable stroke amplitude conditions. The wear rate is the maximum under the variable cycle temperature condition. According to the dissipated energy calculation, the difference between the two different stroke amplitudes is the biggest among all the conditions. EBSD and TEM analyses show that the subsurface of variable stroke amplitude worn scar has a more uniform strain distribution, and reveals a unique subsurface structure with a transformation from crystalline to amorphous, which contributes to improving the wear resistance. This work provides insights into coating microstructure stability and wear mechanisms under variable cycle conditions.

Design and Control of DVR Based on Adaptive Bateman Polynomial for Power Quality Improvement

ABSTRACTPower quality issues encompass a spectrum of disturbances that affect the stability and reliability of the power supply. This study explores voltage‐related anomalies, including sags, surges, flickers, unbalances, harmonics, interruptions, and swells, examining their origins, characteristics, and repercussions. These issues arise from a myriad of sources, such as load fluctuations, equipment malfunctions, and grid dynamics. The ramifications of these disturbances extend to equipment malfunctions, reduced operational efficiency, and financial losses. Dynamic voltage restorer (DVRs) are series custom power devices for mitigating these voltage‐related anomalies and use real‐time monitoring and control to quickly inject exact voltages into the grid during disruptions, restoring voltage levels to acceptable levels. This study demonstrates the capacity of DVRs to successfully alleviate power quality concerns, hence improving equipment dependability and system stability by analyzing case studies and simulation findings. The control system used to supply switching signals to the voltage source converter (VSC) of the DVR is based on adaptive Bateman polynomial (ABMP). Traditional DVR control techniques often rely on fixed or linear control strategies, which may not adequately handle varying load conditions and disturbances. ABMP offers an adaptive approach where the control parameters can adjust dynamically based on real‐time system conditions. This adaptive capability enhances the accuracy of voltage restoration, ensuring that the DVR responds optimally to varying loads and disturbances. During voltage sag and swell conditions at the grid side, the VSC injects the compensating voltage in series with the feeder with a constant switching frequency. A battery energy‐supported system (BESS) based DVR is considered for the proposed system. The supply is connected to the critical and sensitive loads. The proposed control scheme is validated through extensive simulation and experimental results.

Experimental investigation of quarry rock dust incorporated fly ash and slag based fiber reinforced geopolymer concrete circular columns

Manufacturing ordinary Portland cement (OPC) poses significant challenges for sustainable construction practices. OPC manufacturing emits substantial greenhouse gases into the atmosphere and demands extensive raw materials. In pursuit of greener alternatives, researchers explore geopolymer concrete (GPC), a revolutionary material that entirely replaces OPC, comprising industrial wastes/by-products activated through an alkaline solution. The study aims to investigate the feasibility of incorporating quarry rock dust (QRD) into GPC production for environmentally sustainable structural applications. Circular columns (200 mm diameter, 1000 mm length) were formulated using GPC blends with fly ash, slag (SG), and QRD as a partial SG replacement. The structural performance of these columns, with and without steel fiber reinforcement, was evaluated under varied loading conditions. Results show that QRD is a valuable ingredient in GPC for structural concrete elements, offering performance comparable to traditional OPC concrete. Furthermore, the incorporation of steel fibers significantly enhances the peak axial loads, displacement response, and overall performance of GPC columns with or without QRD. Fiber-reinforced GPC columns demonstrated approximately 8–10% higher ultimate load capacity than equivalent OPC columns. Eccentricity was found to significantly reduce ductility, but fiber reinforcement offers substantial ductility improvements (25–55%).

Linear Active Disturbance Rejection Control System for the Travel Speed of an Electric Reel Sprinkling Irrigation Machine

The uniformity of the travel speed of electric reel sprinkling irrigation machines is a key factor affecting irrigation quality. However, conventional PID control is susceptible to sudden disturbances under complex farmland conditions, leading to reduced speed uniformity. To enhance the robustness of the control system, it is necessary to investigate new disturbance rejection control algorithms and their effects. Therefore, a kinematic model of the reel sprinkling irrigation machine and a brushless DC (BLDC) motor model were established, and a linear active disturbance rejection control (LADRC) strategy based on improved particle swarm optimization (IPSO) was proposed. The simulation results show that under variable speed conditions, the system exhibits no overshoot, with an adjustment time of 0.064 s; under variable load conditions, the speed vibration amplitude is less than 0.3%. The field test results indicate that at travel speeds of 10 m/h and 30 m/h, the maximum absolute deviation rate under IPSO-LADRC control is reduced by 27.07% and 13.98%, respectively, compared to PID control. The control strategy based on IPSO-LADRC effectively improves the control accuracy and robustness under complex farmland conditions, providing a reference for enhancing the control performance of other electric agricultural machinery.

Experimental study on dynamic mechanical properties of multidirectional constrained water-bearing coal samples under dynamic-static coupling loading

The objective of this study is to investigate the dynamic mechanical properties of coal and rock under deep water conditions. The research employs an enhanced Split Hopkinson Pressure Bar (SHPB) testing system. Five sets of dynamic impact experiments were conducted on coal samples under varying loading conditions to analyse the changes in dynamic strength, energy dissipation, fractal dimension and other characteristics of coal samples under different water content states were analyzed. The experimental results demonstrate that: (1) Under specific strain rate conditions, the dynamic strength of saturated coal samples is lower than that of natural coal samples. As the strain rate gradually increases, the bonding force generated by free water and the Stefan effect jointly act, and the peak strength of saturated coal samples under high strain rate loading conditions is higher than that of natural coal samples. (2) Under certain strain rate conditions, the absorption energy of saturated coal samples is approximately 10% to30% lower than that of natural coal samples, and deformation hysteresis phenomenon occurs in natural coal samples, thereby improving the dynamic strength of natural coal samples relative to saturated coal samples; (3) The fractal dimension of saturated coal samples with a specific strain rate under three-dimensional dynamic static combination loading is higher than that of natural coal samples, and the percentage of small particle coal samples with debris is higher than that of natural coal samples; Finally, based on the HJC model, some coal samples were selected to simulate the coal rock failure characteristics during the triaxial loading process using ANSYS/LS-DYNA, and their stress–strain curves and failure morphology diagrams were obtained. The discrepancy between the numerical simulation and the experimental results was less than 10%, thereby further elucidating and corroborating the coal failure process and dynamic mechanical characteristics.

Establishing high temperature tribological performance and wear mechanism map of engineered in-situ TiB2 reinforced Mg-RE metal matrix composites

The high temperature sliding wear behavior of microstructurally engineering in-situ sub-micron sized TiB2 reinforced ZE41 composite was studied and compared with it’s base counterpart at varying loading conditions. The wear mechanism maps were constructed by correlating the microstructures of worn surfaces with different test parameters. The severe and catastrophic wear mechanisms like delamination and melt wear were wider in base and composite, while in the case of engineered composite, these zones are significantly narrow down. Due to the presence of thermally stable in-situ TiB2 particles and bimodal precipitates in engineered composite, the material showed sufficient resistance against wear induced deformation. Furthermore, the study established scientific knowhow on high-temperature wear induced deformation behavior by analyzing microstructural evolution in wear subsurface zone.

Design, analytical and computational analysis, and development of a high-precision CNC spindle for a vertical machining center

This research focuses on design, simulation and development of a high precision Computer Numerically Controlled (CNC) spindle for vertical machining center. High speed spindle is designed and analyzed under the varying load conditions. SolidWorks 2020 is used for designing of CNC spindle (based on ISO BT40 standards) and ANSYS Workbench 2020 is used for analysis. Moreover, analytical calculations for deformation are also done. Three different materials i.e. AISI 4340 steel, Grey cast iron, and Ti6Al4V alloy are chosen for the analysis. Effect of varying load on deformation and stress on CNC spindle is discussed. AISI 4340 steel showed better mechanical characteristics as compared to other materials. Moreover, the results showed that steel gives lesser values of deformation as compared to other materials, when applied under different load conditions. Although Grey cast iron can be economical and weight of the spindle can also be reduced but Grey Cast iron has greater value of deformation when load is applied. On the other hand, Ti6Al4V alloy specimen exhibited less stress as compared to other materials but mechanical properties in terms of modulus of elasticity are not that good as AISI 4340 steel. So, AISI 4340 steel could be a good option for spindle materials that require desired properties such as strong corrosion resistance, tensile strength, yield strength, and propagation. This will boost the accuracy and efficiency of spindle. Based on these results, high-precision CNC spindle was developed.

Enhancing voltage regulation in high-speed digital circuits: A simulation-based analysis of the modified Ohm's law

Voltage droop is a significant challenge in high-speed digital circuits, impacting the reliability and performance of electronic systems. This paper introduces a novel approach based on a Modified Ohm's Law to address this issue. By incorporating nonlinear resistance effects, the Modified Ohm's Law provides a more accurate representation of circuit behavior, particularly under dynamic conditions. Through a rigorous simulation framework, the behavior of power supply models under varying load conditions is analyzed. The paper systematically examines circuit responses, load variations, and power supply dynamics, integrating both Standard and Modified Ohm's Law to compare their effectiveness in voltage regulation. The simulation results indicate that the Modified Ohm's Law provides a more accurate prediction of voltage behavior, particularly under rapid load changes, leading to significant improvements in voltage stability. The applied parameter sweep analyses reveal that adjusting the time constant of the power supply within the Modified Ohm's Law framework yields superior voltage regulation compared to traditional methods. Additionally, the analysis of frequency and amplitude variations demonstrates the robustness of the Modified Ohm's Law in maintaining voltage stability across different operational scenarios. This approach effectively addresses the nonlinearities in resistance, reducing voltage droop and enhancing the reliability of high-speed digital circuits. The findings demonstrate the potential of the Modified Ohm's Law in practical applications, suggesting further research and real-world experimentation to fully explore its benefits and implementation strategies. This work contributes to the advancement of voltage regulation techniques, offering a robust solution to the persistent problem of voltage droop in modern electronic systems.

Experimental investigation and computational modelling of 304LN stainless steel under constant and variable strain path multiaxial loading conditions

This study investigates the fatigue behavior of 304LN stainless steel under constant and variable strain path multiaxial loading conditions. Experimental methods and computational modelling were used to analyze the response of the material to different loading scenarios. Experimental investigations were conducted to gather empirical data, which were subsequently validated using a modified Ohno-Wang and Tanaka cyclic plasticity framework. Two models were used for the analysis: the MOT model and a modified model that incorporated a weighted function and fractional functions for hardening and softening. In contrast, the modified model offers significant improvements, accurately capturing primary hardening and secondary softening across all loading scenarios. Furthermore, the modified model effectively simulates transient behavior, including load alteration and recovery effects, due to the integration of load history memory regulating functions. Overall, this study emphasizes the importance of considering the complexities of cyclic loading and the sensitivity of the material behavior to the loading history.