Dissipative Behavior Research Articles

On the Fractional Dynamics of Kinks in Sine-Gordon Models

In the present work, we explored the dynamics of single kinks, kink–anti-kink pairs and bound states in the prototypical fractional Klein–Gordon example of the sine-Gordon equation. In particular, we modified the order β of the temporal derivative to that of a Caputo fractional type and found that, for 1<β<2, this imposes a dissipative dynamical behavior on the coherent structures. We also examined the variation of a fractional Riesz order α on the spatial derivative. Here, depending on whether this order was below or above the harmonic value α=2, we found, respectively, monotonically attracting kinks, or non-monotonic and potentially attracting or repelling kinks, with a saddle equilibrium separating the two. Finally, we also explored the interplay of the two derivatives, when both Caputo temporal and Riesz spatial derivatives are involved.

Analytical and Computational Investigation of VibroThermoAcoustic Behaviour of Cracks in Aerostructures

Abstract This research investigates the Vibro-thermoacoustic dynamics exhibited by Aerostructures, particularly those harbouring surface cracks. Employing a novel approach, a Thermo-Acoustic field coupled Transient Heat Transfer model is developed to model the interplay among vibrations, heat dissipation, and acoustic behaviour at crack tip interfaces. Local surface flaws proximal to stress concentration sites are investigated via the Newmark Beta Method and Finite Element Analysis, which are applied to displacement and thermal mapping at crack tips through temporal and spatial discretization. Recognizing the implications of flaws in structural integrity and potential lifespan reduction, the study incorporates Analytical, Numerical and Computational analysis of surface cracks into the broader context of Thermoacoustic phenomena. 
The paper explores the application of Elastoplastic Fracture Mechanics (EPFM) to model the impact of plastic deformation on crack growth, local acoustic field and the overarching structural integrity of these components. 
In this study, we also investigate the limitations of the original Ramberg-Osgood equation, particularly in its application to modelling nonlinearities in plastic strain at crack tip interfaces. To address these shortcomings, we propose a novel modified Ramberg-Osgood formulation that incorporates Padé Approximants. This modification enables effective modelling of nonlinear stress-strain variations of high-performance materials while improving computational performance and accuracy. 
Real-world aerostructures experience varying loads, and incorporating these principles in our coupled model allows for accurate modelling of Thermoacoustic Field variations and Instability under dynamic conditions. The research offers valuable perspectives for engineering applications, providing a computational roadmap for thermoacoustic modelling in Aerostructures with cracks.

Vibration reduction of rotor systems using magneto-rheological elastomeric supports

Support characteristics (stiffness and dissipation) are well understood to influence the dynamic behaviour of rotors. Supports play an essential role in deciding the stability and response of the rotors. Therefore, frequency-dependent support characteristics are beneficial in determining the rotor response as the frequency of excitation keeps changing. An elegant choice of making rotor supports is by using magneto-rheological elastomeric (MRE) materials. The magnetic field application results in a change in the stiffness and dissipation behaviour of MREs and consequently influences the dynamics of the rotor–shaft system. An attempt is made in this work to conceptualize the MRE as viscoelastic sectors put between the outer race of a bearing and the bearing housing to make the rotor support. A rigorous analytical formulation is done to obtain the stiffness and dissipation of the support so formed in terms of a viscoelastic model of the material under the effect of dispersed magnetic material, the geometry of the sectors, the intensity of the magnetic field, and the frequency of forcing function the supports are subject to. The supports show promising results by reducing the vibrations at resonance by suitably applying the magnetic field. Therefore, MRE materials may be proposed as adaptive supports to both structures and rotors to induce intended dynamic behaviour.

Compression-compression fatigue of quasi-isotropic laminates: Failure mechanisms and link between dissipative behavior and fatigue life

Compression-compression fatigue of quasi-isotropic laminates: Failure mechanisms and link between dissipative behavior and fatigue life

Cloud Crushing and Dissipation of Uniformly Driven Adiabatic Turbulence in Circumgalactic Media

The circumgalactic medium (CGM) is responsive to kinetic disruptions generated by nearby astrophysical events. In this work, we study the saturation and dissipation of turbulent hydrodynamics within the CGM through an extensive array of 252 numerical simulations with proper cooling mechanisms and a large parameter space spanning average gas density, metallicity, and turbulence driving strength. A dichotomy emerges in the dynamics dissipation behaviors upon turbulence driving turnoff. Hot and subsonic disturbances are characterized by weak compression and slow dissipation, while warm and supersonic turbulences are marked by significant compression shocks and subsequent rapid cooling. In the supersonic cases, the kinetic energy decay is divided into a rate-limiting phase of shock dissipation and a comparatively swift phase of thermal dissipation, predominantly occurring within the overdense regions. Dense clouds are crushed on relatively brief timescales of ∼30–100 Myr, depending on turbulence driving strength but independent from average gas density. This independence is in spite of the complex interplay between the kinetics and thermodynamics of dissipation. The brevity of such timescales relative to typical dynamical timescales within the CGM suggests turbulent clouds must be cotemporal with turbulence driving sources such as cool accretion flows or feedback from the interstellar medium. Quantitative results from this work contribute a novel data set of dissipation timescales that incorporates thermodynamics and radiative cooling in an area of study typically focused on kinematics, which may serve as a valuable asset for forthcoming simulations that aim to explore gas dynamics on galactic and cosmological scales.

Numerical Investigation and Cross‐Section Type Selection of Concrete‐Filled Double Steel Plate (CFDSP) Composite Shear Walls Under Cyclic Loading

ABSTRACTConcrete‐filled double steel plate (CFDSP) composite shear walls have excellent seismic performance and are generally used as lateral resistance for high‐rise buildings. However, the numerical simulation of such walls is complicated because of the complex contact between the concrete, the external steel plate, and the shear studs. Eighteen CFDSP walls in the present literature were numerically simulated under cyclic and constant axial loading, and the accuracy was evaluated by comparing them with the experimental results. Then, the impact of cross‐section variations on the structural performance of CFDSP walls under the same steel content ratio was numerically investigated. Designed numerical walls were evaluated under the same loading conditions with four distinct cross‐sections for comparative analysis. Finally, parametric analysis was performed to observe the influence of aspect ratio, steel thickness, and stud spacing on the seismic performance of CFDSP walls. The analysis results show that the proposed numerical model can accurately recover the hysteretic curves of CFDSP walls regarding strength reduction, energy dissipation, and pinch behavior.

Impact of structural characteristics on energy-absorption of 3D-printed thermoplastic polyurethane line-oriented structures

Purpose Additive manufacturing offers the ability to produce complex, flexible structures from materials like thermoplastic polyurethane (TPU) for energy-absorption applications. However, selecting optimal structural parameters to achieve desired mechanical responses remains a challenge. This study aims to investigate the influence of key structural characteristics on the energy absorption and dissipation behavior and the deformation process of 3D-printed flexible TPU line-oriented structures. Design/methodology/approach Samples with varying line orientations and infill densities were fabricated using material extrusion and subjected to quasi-static compression tests. The design of experiments methodology explored the significance of design variables and their interaction effects on energy absorption and dissipation. Findings The results revealed a statistically significant interaction between infill density and orientation, highlighting their combined influence; however, the effect was less pronounced compared to infill density alone. For low-density structures, changing the orientation from 0°/90° to 45°/−45° and increasing infill density enhanced energy absorption and dissipation, while high-density structures exhibited unique energy absorption behavior influenced by deformation patterns and heterogeneity levels. This study facilitates the prediction of mechanical responses and selection of suitable TPU line-oriented printed parts for energy absorbing applications. Originality/value To the best of the authors’ knowledge, the present work have investigated for the first time the energy-related responses of flexible line-oriented TPU structures highlighting the distinction between the low and high density structures.

Quantum switch instabilities with an open control

The superposition of causal orders shows promise in various quantum technologies. However, the fragility of quantum systems arising from environmental interactions, leading to dissipative behavior and irreversibility, demands a deeper understanding of the possible instabilities in the coherent control of causal orders. In this work, we employ a collisional model to investigate the impact of an open control system on the generation of interference between two causal orders. We present the environmental instabilities for the switch of two arbitrary quantum operations and examine the influence of environmental temperature on each potential outcome of control post-selection. Additionally, we explore how environmental instabilities affect protocol performance, including switching between mutually unbiased measurement observables and refrigeration powered by causal order superposition, providing insights into broader implications.

Fatigue Life Prediction of LF6 Aluminum Alloy Laser‐Arc Hybrid Welded Joints Based on Energy Dissipation Method

ABSTRACTTo accurately characterize the heat dissipation behavior of LF6 aluminum alloy laser arc composite welded joint under low cycle fatigue, two fatigue life prediction methods based on dissipated energy were proposed. The experimental investigation has revealed four stages in the evolution of surface temperature increment, including initial temperature increase, subsequent decline, attainment of thermal equilibrium, and sudden temperature escalation leading to failure. Based on the energy dissipation method, two models predicting lifespan of welded joints have been formulated. Model I incorporates the effects of stress amplitude and mean stress, on lifetime demonstrating a strong linear correlation particularly under high‐stress level according to experimental comparisons. Model II introduces a relationship between plastic strain amplitude and inherent dissipated energy to assess fatigue life of welded joints. Digital imaging correction technique has been utilized to quantify plastic strain amplitude. The predicted results from Model II agree well with experimental data.

Stochastic generalized standard materials and risk-averse effective behavior

In this work, we develop a theoretical formulation for describing dissipative material behaviors in a stochastic setting, using the framework of Generalized Standard Materials (GSM). Our goal is to capture the variability inherent in the material model while ensuring thermodynamic consistency, by employing the mathematical framework of stochastic programming. We first show how average behaviors can be computed using the expected value of the free energy and dissipation pseudo-potentials. We then introduce the concept of a risk-averse effective measure, which provides both an optimistic and a pessimistic estimate of the uncertain material behavior. To this end, we utilize the Conditional Value-at-Risk, a widely used risk measure in mathematical finance. We also demonstrate how these concepts can be extended to variational problems at the structure scale, allowing us to compute the effective response of a structure composed of a stochastic material.

Cyclic performance evaluation and hysteretic modelling of a brace-type damper with multi-phase energy dissipation

This paper presents an experimental investigation of a novel brace-type damper for seismic mitigation in steel truss framed structures. The damper exhibits a two-stage energy dissipation behaviour by combining friction damping and yielding of steel struts. The two-stage design allows for adaptability and adjustability to different levels of earthquake events. During low-to-medium intensity seismic events, the friction mechanism is responsible for energy dissipation. While during high-intensity events, the yielding of steel struts is activated to provide additional damping and ensure effective energy dissipation. A test programme comprising five proof-of-concept specimens was conducted to investigate the seismic performance of the damper. The test results demonstrated the anticipated two-stage energy dissipation sequence with exceptional ductility. The sliding surface pairs of stainless steel/mild steel and brass/mild steel performed more stable and predictable friction behaviour compared to surface pairs of mild steel/mild steel. To facilitate practical design of the novel dampers, theoretical hysteretic models were developed to quantify critical mechanical quantities of the damper. The adequacy of the design model was validated by comparing the test responses with the design predictions. The hysteretic model offered a quantitative framework for analysing and predicting the response of brace under cyclic loading.

Physics-informed neural networks and higher-order high-resolution methods for resolving discontinuities and shocks: A comprehensive study

Addressing discontinuities in fluid flow problems is inherently difficult, especially when shocks arise due to the nonlinear nature of the flow. While handling discontinuities is a well-established practice in computational fluid dynamics (CFD), it remains a major challenge when applying physics-informed neural networks (PINNs). In this study, we compare the shock-resolving capabilities of traditional CFD methods with those of PINNs, highlighting the advantages of the latter. Our findings show that PINNs exhibit less dissipative behavior compared to conventional techniques. We evaluated the performance of both PINNs and traditional methods on linear and nonlinear test cases, demonstrating that PINNs offer superior shock-resolving properties. Notably, PINNs can accurately resolve inviscid shocks with just three grid points, whereas traditional methods require at least seven points. This suggests that PINNs are more effective at resolving shocks and discontinuities when using the same grid for both PINN and CFD simulations. However, it is important to note that PINNs, in this context, are computationally more expensive than traditional methods on a given grid.

Experimental and numerical study on the torsional behavior of rectangular hollow reinforced concrete columns strengthened By CFRP

This paper reported a series of hysteretic torsion experiment to investigate the torsional behavior of rectangular hollow reinforced concrete (RHRC) column strengthened by fiber reinforced polymer (FRP). Six RHRC column specimens with different number of longitudinal reinforcements, spacing of stirrup and strengthening method using FRP were designed. One was not strengthened, four were strengthened with CFRP, one was strengthened with CFRP and GFRP. The experimental results showed that the primary failure modes of specimens were the spalling of surface concrete with the detachment of FRP. In details, under the hysteretic torsional load, the interaction between adhesive and concrete caused the intersecting diagonal cracks in the internal concrete. Compared with the hysteretic curve of specimen without FRP strengthening, FRP strengthening can significantly improve the initial stiffness by 50 % and peak torsional strength by 70 %. For RHRC column without strengthening, the fullness was poor because of the weak torsional energy dissipation. The FRP strengthening can also enhance the torsional energy dissipation and seismic behavior of RHRC column. To predict the complex torsional behavior of RHRC column strengthened by FRP, a finite element (FE) model and a constitutive model were developed. The FE model considered potential cracks in concrete and FRP–concrete interface based on the application of the cohesive zone model (CZM), whereas the constitutive model accounted for interface damage and plasticity. The results of the performed simulations indicated that the proposed model can effectively represent the hysteretic mechanical behavior of columns under torsional load, which cannot be achieved using conventional FE methods.

A New 6D Two-wing Hyperhaotic System: Dynamical Analysis, Circuit Design, and Sinchronization

This paper introduces a novel 6D dynamic system derived from modified 3D Lorenz equations of the second type using state feedback control. While the original 3D equations are formally simpler than the classical Lorentz equations, they produce topologically more complex attractors with a two-winged butterfly structure. The proposed system contains the fewest terms compared to existing literature. These terms comprise two cross-product nonlinearities, two piecewise linear functions, six linear terms, and one constant. The new 6D hyperchaotic system exhibits a rich array of dynamic characteristics, including hidden attractors and dissipative behavior. A thorough dynamic analysis of this system was performed. In particular, bifurcation diagrams were constructed, Lyapunov exponents and dimensions were calculated, and multistability and offset boosting control were analyzed to understand the systems behavior further. An electronic circuit of the 6D hyperchaotic two-winged butterfly system was developed in the Multisim computer environment. The designed electronic circuit showed excellent agreement with the simulation results of the new 6D dynamic system. Synchronization of two identical 6D hyperchaotic systems was achieved using the active control method.

Analysis of bolt bonding surfaces by the finite element method based on the equivalent Iwan model

This study establishes a finite element model based on the Iwan model to accurately characterize the force–displacement relationship and energy dissipation in bolted joints under small-amplitude tangential displacement. The force–displacement behavior of the Iwan model is transformed into a stress–strain relationship using a hybrid hardened intrinsic model. A subroutine developed with UMAT and UHARD is used to simulate the elastic–plastic behavior of the Iwan model during surface contact in the finite element model. Three-dimensional modeling and joint simulation are conducted using ABAQUS software. Experimental data verify the model's validity, and the effects of multiple factors on the bolted bonding surface are analyzed. The influence of friction coefficient, cyclic displacement amplitude, and preload on the force–displacement relationship of the bolted bonding surface is explored. Polynomial interpolation of the loading and unloading curves is applied to investigate the energy dissipation phenomenon. Results show that the finite element method can effectively reflect the hysteresis and energy dissipation behavior of the bonding surface. Increased friction coefficient and preload improve residual stiffness and energy dissipation capacity, while larger cyclic displacement amplitudes increase energy dissipation but have a minimal effect on residual stiffness.

Research of Design Technology of Printed Circuit Board

This paper delves into various methodologies for enhancing the quality, design, and optimization of Printed Circuit Boards (PCBs). With the development of the technology, the importance of Printed Circuit Board(PCB) is recently mentioned by more and more people who is trying to make progress of human technology. The classification of PCB defects, a crucial step in ensuring product reliability, is discussed on several categories of defects in PCB, highlighting recent advancements such as fuzzy c-means segmentation, which significantly improves defect detection accuracy. When producing, the layout is quite significant. In a conference, a group of scientists used a thermal layout modelling and optimization routine to make the board having more space to put circuit on it. Methods to ensure PCB quality during production are examined, focusing on optical and electrical testing. The PCB design process is also explored, emphasizing the importance of those considerations before production. Finally, the paper reviews innovative approaches to PCB layout optimization, particularly in managing heat dissipation and dynamic behavior through advanced simulation techniques.

Evaluation of Inherent Damping Feature of Beam Structure Based on Complex Modulus

Structural damping, which has been widely used to quantify the energy dissipation of engineering structures, plays an important role in dynamic analysis during the design phase and the assessment of existing structures. However, the development of an accurate damping model remains an open question due to the unclear mechanism. In this study, structural damping was identified based on loss factors for beam structures, which were used for presenting the damping behavior during vibrations. The equation of motion for the bending deformation of a Timoshenko beam was derived, accounting for the material damping. To identify the loss factor of the beam from the response signals at a limited number of measurement points, an inverse algorithm based on wave coefficient estimation was developed, considering the numerical stability for data interpretation. Based on the proposed loss factor identification method, several beam models with different shapes of cross-sections were investigated, focusing on the feasibility of the method of varying cross-section cases. Comparing the spectral element model with the loss factor and the finite element model with Rayleigh damping, it was confirmed that the loss factor can better describe the actual energy dissipation behavior of the structure. It provides a more accurate theoretical model for estimating structural damping in practical engineering.

The comparative analysis of energy dissipation behaviour of woven and UD para-aramid fabrics

This research examines how impact energy spreads across para-aramid fabrics, comparing woven and unidirectional types, using 2-D Thin Plate Spline analysis. The experiment involved dropping a weighted hemisphere onto fabric samples and measuring their deformation across different layer counts. To assess how yarn orientation affects energy dispersion, panels with 0º/90º and 0º/90º/±45º configurations were tested. By analysing the fabric's shape changes under impact, the study revealed patterns of energy propagation. Calculations of bending energy and expansion factors provided insights into this behaviour. The findings indicate that unidirectional fabrics outperform woven structures in distributing impact energy across their surface. Moreover, incorporating ±45º fibre reinforcements in both fabric types enhances energy dispersion and mitigates impact effects.

Identification of dimethachlon metabolites and dissipation behavior, processing factor and risk assessment of dimethachlon in rapeseed

Pesticides and their transformation products are found in raw agricultural and processed food products, posing risks to human health. Therefore, a thorough investigation of dimethachlon’s dissipation, metabolites, residue levels in crops, and changes during food processing is essential for an accurate dietary risk assessment. This study identified two metabolites, 4-(3,5-dichloroanilino)-4- oxobutanoic acid (DCBAA) and 3,5-dichloroaniline (3,5-DCA), formed from dimethachlon in crops under field conditions. A precise and sensitive analytical method was developed to detect dimethachlon, DCBAA, and 3,5-DCA in rapeseed pods, seeds, and oil. The half-lives of dimethachlon in rapeseed pods at two sites ranged from 1.61 to 1.67 days. During degradation, the maximum residue levels of DCBAA and 3,5-DCA in rapeseed pods reached 38.59 % and 3.47 % of the initial parent compound concentration, respectively. At harvest (day 10), final dimethachlon residues in rapeseed were 0.11 mg/kg and 0.27 mg/kg. Processing rapeseed into oil through sun-drying and stir-frying reduced dimethachlon residues, with processing factors (PF) of 0.69 and 0.64, respectively. However, pressing the seeds concentrated dimethachlon in the oil, with a PF of 1.92. Notably, DCBAA tended to concentrate during sun-drying but decreased during stir-frying and pressing. Supervised trials indicated that dimethachlon residues in rapeseed posed no long-term dietary risks.

Uncovering the Fracturing Mechanism of Granite Under Compressive–Shear Loads for Sustainable Hot Dry Rock Geothermal Exploitation

Shear-dominated hazards, such as induced earthquakes, pose an escalating threat to the sustainability and safety of the geothermal exploitation. Variations in fault orientations and compression–shear stress ratios exert a profound influence on the failure processes underlying these disasters. To better understand these effects on the shear failure mechanisms of hot dry rocks, mode-II fracturing tests on granites were conducted at varying loading angles (specifically, 55°, 60°, 65°, and 70°). These tests were accompanied by a comprehensive analysis of the mechanical properties, energy dissipation behavior, acoustic emission (AE) responses, and digital image correlation (DIC)-extracted displacement fields. The tensile–shear properties of stress-induced microcracks were discerned via AE characteristic parameter analysis and DIC displacement decomposition, and the mode-II fracture energy release rate was quantitatively characterized. The results reveal that with increasing compression–shear loading angles, the mechanical properties of granites are weakened, and the elastic strain energy at peak stress gradually decreases, while the slip-related dissipated energy increases. Throughout the fracturing process, the AE count progressively climbs and reaches a peak near catastrophic failure, with an upsurge in low-frequency and high-amplitude AE events. Microcrack distribution concentrates aggregation along the shear plane, reflecting the emergent displacement discontinuities evident in DIC contours. Both the AE characteristic parameter analysis and DIC displacement decomposition demonstrate that shear-sliding constitutes the paramount mechanism, and the fraction of shear-oriented microcracks and the ratio of tangential versus normal displacement escalate with increases in shear stress. This analysis is supported by the heightened propensity for transgranular microcracking events observed through scanning electron microscopy. As the shear-to-compression stress increases, the energy concentration along the shear band intensifies, with the gradient of the fitting line between cumulative AE energy and slip displacement steepening, indicative of a heightened mode-II energy release rate. These results contribute to a deeper understanding of the mode-II fracture mechanism of rocks, thereby providing a foundational basis for early warnings of shear-dominant geomechanical disasters, and improving the safety and sustainability of subsurface rock engineering.