Dissipated Energy Approach Research Articles

Dynamics of Snowflakes Impacting Superhydrophobic Surfaces.

Snow and ice accumulation on surfaces presents significant safety and efficiency challenges across various industries, necessitating the development of effective mitigation strategies. In this study, the dynamics and energy dissipation of natural snowflakes impacting superhydrophobic surfaces (SHS) were explored using high-speed imaging and a novel image processing method. The size, velocity (impact and bounce), and contact time of natural wet snowflakes were quantitatively analyzed, identifying two primary impact outcomes: bouncing and fragmentation. The analysis focused on bouncing to study the coefficient of restitution (COR) of snowflakes. It was found that small snowflakes (<1.40 mm in diameter) with low impact velocities (<2.90 m/s) tend to be bounced, whereas larger, faster snowflakes are more likely to be fragmented. For the first time, the contact time of natural snowflakes on SHS was also reported, introducing a dimensionless contact time (DCT) for quantifying energy dissipation during the impact. The results indicate that energy dissipation has a cubic relationship with snowflake size and a quadratic relationship with its impact velocity, demonstrating that larger and faster snowflakes dissipate more energy. It is observed that a reduction in DCT leads to an exponential increase in COR and a decrease in normalized energy dissipation, supporting the theoretical prediction that the COR approaches one and the normalized energy dissipation approaches zero as the DCT approaches zero. These results are significant for enhancing the design and efficiency of anti-icing surfaces, contributing to the development of models that simulate snow accumulation behaviors and inform better design of both active and passive snow mitigation strategies.

Energy Dissipation during Wenzel Wetting via Roughness Scale Interface Dynamics.

A numerical method is proposed to simulate the roughness scale interface dynamics of a slow-moving fluid interface as it advances over a chemically homogeneous rough surface. Analysis of the governing augmented Navier-Stokes and Young's boundary condition equations shows how the local interface behavior can be represented via a series of incrementally advanced equilibrium interfacial morphologies. Combined with a roughness scale mechanical energy balance [Harvie, D. J. E. Contact-angle hysteresis on rough surfaces: mechanical energy balance framework. J. Fluid Mech. 2024, 986, A17], the simulations are used to calculate the energy dissipation associated with a surface decorated with a periodic array of round-edge square pillars. This dissipation is used to predict static contact angle hysteresis (CAH) from knowledge of just the surface roughness topography and equilibrium contact angle. We show that the energy dissipated varies approximately as ϕln ϕ (with ϕ being the area fraction), becoming zero as ϕ → 0. The CAH predicted by our method is in good agreement with the experimental results of Forsberg et al. [Forsberg, P. S.; Priest, C.; Brinkmann, M.; Sedev, R.; Ralston, J. Contact line pinning on microstructured surfaces for liquids in the Wenzel state. Langmuir 2010, 26, 860-865], thereby demonstrating that our numerical method of simulating interfacial dynamics adequately captures the real interface motion, as well as illustrating how far-field contact angle and energy dissipation approaches are consistent for this surface. We also compute CAH for an interface moving at 45° to the surface periodicity direction to show that the experimental measurements are bracketed by the 0° and 45° advance direction results. The proposed method opens up the field to quantitative analysis, surface functionalization, and design for different specific applications.

A cumulative damage model for predicting and assessing raveling in asphalt pavement using an energy dissipation approach

A cumulative damage model for predicting and assessing raveling in asphalt pavement using an energy dissipation approach

Three-dimensional analysis of thermoelastic damping in couple stress-based rectangular plates with nonlocal dual-phase-lag heat conduction

Since thermoelastic damping (TED) plays a decisive role in the functioning of micro/nanoresonators, accurate assessment of its magnitude in these tiny systems is imperative. Successfully simulating the thermomechanical behavior of various mechanical elements requires consideration of heat transfer in all three principal directions. Furthermore, there is no denying the impact of size on the mechanical and thermal domains. In light of these reasons, the current study strives to create a three-dimensional (3D) size-dependent TED model for rectangular micro/nanoplates via the use of the modified couple stress theory (MCST) and nonlocal dual-phase-lag (NDPL) heat transfer model concurrently for the first time. To accomplish this, by applying the Galerkin method to the 3D NDPL-based heat equation, the relation of temperature field is derived. Moreover, the coupled thermoelastic constitutive relations are extracted by including the couple stress effect. Lastly, by exploiting the obtained relations in the energy dissipation approach, an analytical TED formula in the form of infinite trigonometric series is attained. To appraise the rightness of derived formulation, the method of model reduction is applied. Moreover, an elaborate convergence analysis is implemented to realize the number of sufficient terms of the provided solution that result in well-grounded outcomes. A rigorous simulation study is also accomplished on the role of 3D heat conduction, scale parameters of MCST and NDPL model, boundary constraints, geometry and material in the variations of TED. Findings imply the definite impact of heat conduction dimension on TED value in rectangular plates with a large ratio of thickness to length and width.

On the post-impact fatigue behavior and theoretical life prediction of CF/PEEK-titanium hybrid laminates using an energy dissipation approach

This paper aims to illustrate the effect of the impact damage on fatigue behavior of CF/PEEK-titanium hybrid laminates. To achieve this end, a fatigue life model was proposed to predict the S–N curves of the laminates at various initial impact energy levels and stress ratios based on the energy dissipation approach. The energy dissipation behavior of the laminates during fatigue loading under different experimental conditions was analyzed through a large amount of post-impact fatigue tests, and the correlation between the initial impact damage and the total fatigue dissipation energy was determined. The full-field axial strain distribution of the titanium layer on the impacted side of the laminate was characterized in terms of initial impact energy level and maximum stress using digital image correlation, and then the post-impact fatigue failure mechanism of CF/PEEK-Ti hybrid laminates was summarized. Finally, the validity of the proposed model was verified by fatigue tests under other conditions of stress ratio and impact energy level. It is worth mentioning that the proposed model is also applicable to other types of FMLs, and can accurately predict the residual fatigue life of laminates after impact with only one set of S–N curve data.

Wave statistics and energy dissipation of shallow-water breaking waves in a tank with a level bottom

The present study focuses on two-dimensional direct numerical simulations of shallow-water breaking waves, specifically those generated by a wave plate at constant water depths. The primary objective is to quantitatively analyse the dynamics, kinematics and energy dissipation associated with wave breaking. The numerical results exhibit good agreement with experimental data in terms of free-surface profiles during wave breaking. A parametric study was conducted to examine the influence of various wave properties and initial conditions on breaking characteristics. According to research on the Bond number ( $Bo$ , the ratio of gravitational to surface tension forces), an increased surface tension leads to the formation of more prominent parasitic capillaries at the forwards face of the wave profile and a thicker plunging jet, which causes a delayed breaking time and is tightly correlated with the main cavity size. A close relationship between wave statistics and the initial conditions of the wave plate is discovered, allowing for the classification of breaker types based on the ratio of wave height to water depth, $H/d$ . Moreover, an analysis based on inertial scaling arguments reveals that the energy dissipation rate due to breaking can be linked to the local geometry of the breaking crest $H_b/d$ , and exhibits a threshold behaviour, where the energy dissipation approaches zero at a critical value of $H_b/d$ . An empirical scaling of the breaking parameter is proposed as $b = a(H_b/d - \chi _0)^n$ , where $\chi _0 = 0.65$ represents the breaking threshold and $n = 1.5$ is a power law determined through the best fit to the numerical results.

Composite nanofillers with a locust-like cushioned half-moon structure to improve the impact resistance of polyurethane

Developing a highly impact absorption properties polyurethane elastomer with exceptional strength and toughness is crucial in the realm of polyurethane impact protection. Inspired by the energy dissipation structure of the soft and hard bonding in the hind limb of locusts, the paper fixed the dynamic disulphide bonds commonly found in bioproteins after hydroxy-functionalized on SiO2 by quaternization reaction, and is creatively applied in the field of impact resistance as soft and hard sacrifice micro-regions into the polyurethane. Benefiting from the multi-scale energy dissipation approach formed by the breakage of dynamic disulphide bonds, the stress obstruction by rigid particles, and the strong bonding interface between the composite filler and the matrix, polyurethane composite have demonstrated great efficiency in energy absorption and impact protection. The static compression strength of IPS@SiO2/PUE is 148.8% higher compared to neat PUE. Furthermore, the dynamic impact energy absorption of the composite PUE was increased by 109.36%, nearly twice that of the original polyurethane. This study proposes that this strategic approach has the potential to offer a novel method for material design, which facilitates bionic design of high-impact protective elastomers utilizing different energy dissipation mechanisms.

A fast fatigue life estimation method for concrete based on the energy dissipation approach

This study proposed a concrete fatigue life prediction method based on energy dissipation analysis. The fatigue life is estimated by dividing the total critical energy dissipation by the average energy dissipation per cycle. Based on a unified concrete damage model that can be applied to both monotonic and fatigue loading conditions, the total critical energy dissipation value under fatigue loading can be estimated by the stress-strain curve under monotonic loading. The average energy dissipation per cycle is obtained by calculating numerical samples with different strengths. Several numerical examples show that the proposed prediction model can rapidly estimate fatigue life under uniaxial loading with high efficiency and excellent precision.

Nonlocal dual-phase-lag thermoelastic damping in small-sized circular cross-sectional ring resonators

The purpose of current research is to establish a theoretical size-dependent framework for estimating the amount of thermoelastic damping (TED) in miniaturized rings with circular cross section via the nonlocal dual-phase-lag (NDPL) generalized thermoelasticity theory, as one of the most exhaustive non-Fourier heat conduction models. The method used to achieve this goal is based on the definition of TED in the energy dissipation (ED) approach. To do so, after deriving heat equation in the context of NDPL model, the distribution of temperature all over the volume of the ring is specified. Then, the relations of dissipated thermal energy and strain energy in the ring are obtained. Lastly, by employing ED approach, a formula comprising the nonclassical parameters of NDPL model is rendered to determine TED value in small-scaled toroidal rings. By presenting various numerical examples, the dependence of TED on influential parameters including nonclassical thermal constants in NDPL model, ring geometry, vibrational mode number and ring material is surveyed. The Findings enlighten that the inclusion of nonlocal parameter into the model can have conspicuous impacts on TED value, especially in smaller rings or higher vibrational mode numbers. The results also reveal that among the investigated materials (i.e. silicon, copper, silver, and lead), rings made of lead and silicon exhibit the maximum and minimum TED values, respectively.

Enhanced seismic isolation and energy dissipation approach for the aboveground negative-stiffness-based isolated structure with an underground structure

Aboveground structures are increasingly being built in proximity to underground facilities to produce synthetic functions in an intensive space. Targeting multi-seismic performance upgradation and enhanced vibration decoupling, a negative-stiffness amplification system-enabled isolation system (NSAS-IS) is proposed for an aboveground structure within a coupled underground-structure–soil and aboveground-structure–soil system to develop a novel interaction system. The mechanical layout and constitutive model of the NSAS-IS are elaborated, and structural models are established for NSAS-IS-equipped structures built on a fixed base and flexible soil with and without underground structures. The effectiveness and design principle of the NSAS are initially set for the fixed-base condition as a reference, based on which the soil effects with and without the influence of underground structures are distinguished through comparisons. Given the significant impact of flexible soil and underground structures, a generic design framework is proposed for NSAS-ISs employed in underground-structure–soil and aboveground-structure–soil systems. In addition, the enhanced energy dissipation effect of the NSAS and suppressed seismic responses of the soil, ground, and underground structures are illustrated. The obtained results highlight the necessity of incorporating the effects of the soil–structure interaction and underground structures into the performance evaluation and design of NSAS-ISs. Regardless of the soil type and existence of underground structures, NSAS-IS exhibits enhanced energy dissipation efficiency and isolating effects to suppress the seismic performances of the superstructure and isolation layer simultaneously. However, its efficiency could be weakened by complex interactive behaviors when the soil period is close to the isolation period of the NSAS-IS. The proposed design framework can be adopted as a guideline to guarantee the expected isolation effects of the aboveground structure in cases that consider the soil conditions, and simultaneously, the adverse impacts of the aboveground structure imposed on the underground structure can be effectively reduced by the proposed NSAS.

Study on added damping due to resistive shunting on cantilever, simply supported beam, and effect on the variation of amplitude at resonance

The current work determines the piezoelectric damping of resistively shunted beams induced by resistors through joule heating. To predict this damping, a piezoelectric patch [Formula: see text] is attached to the surface of a cantilever beam. The current work emphasizes the effect of various parameters on damping added to the cantilever beam through the energy dissipation approach. This work analyzes different methods for predicting added damping. Results from different approaches rely on the base structure modeshape. Using the energy dissipation method from voltage generation, estimated added damping, included a stepped beam model to account for the curvature of the beam with PZT. Further, the same is validated with existing literature and found to be consistent. With the energy dissipation approach, including the stepped beam model compared with experimental literature data, the accuracy of the adopted beam model is validated. Few critical observations were made, such as the location of the PZT patch plays a vital role in determining the required added damping for a particular mode. This optimal location was the nodal location of the other modes. The location of the piezoelectric patch is an important parameter to achieve the required added damping for a particular mode. The optimal location of PZT to achieve maximum added damping for a particular mode may lie at the nodal location of other modes. This optimal location is addressed by rigorous experiments on a simply-supported beam initially and further correlated to a cantilever beam with the help of an energy dissipation approach. The energy dissipation model is correlated and validated for cantilever beam straight PZT on cantilever beams and a simply supported beam. In practical situations, in ambient conditions, environmental effects may result in a change of resonant frequency and thus amplitude. This variation may alter the base and shunt damping performance attributed to air damping. We have experimentally investigated the influence of air damping for base damping (inherent) and added damping (PZT).

Multiaxial fatigue evaluation of type 316L stainless steel based on critical plane and energy dissipation

AbstractThis paper focuses on a comparative study of the critical plane approach (CPA) and the dissipated energy approach (DEA) for multiaxial fatigue evaluation on an AISI 316L steel. It is a follow‐up to our previous study on the development of a DEA model for multiaxial fatigue life prediction. The results demonstrate that the developed DEA model can provide overall better performance compared with some classic CPA models both in terms of prediction accuracy and versatility to multiaxial loading paths. An in‐depth crack mechanism investigation reveals that the multiaxial fatigue life is mostly spent in the formation of micro‐cracks, which exhibits distinct characteristics under the different loading paths examined. This effect can be better considered by using DEA model compared with the CPA models adopted.

The land use impacts of forestry and agricultural systems relative to natural vegetation; a fundamental energy dissipation approach

In agriculture and forestry the land use impacts that occur during production are important; including as necessary inputs for life cycle assessments. There are major differences in land use impacts between different forest management approaches and, in future, those forestry systems which deliver ecosystem services while having lower adverse land use impacts will be of greater value. Here we examine the land use impacts of seven contrasting forest management approaches and agricultural cropping systems at five locations in Europe. Comprehensive management data were used to calculate land use impacts in an evaluation system based on ecosystem thermodynamics. This approach has a number of advantages, including that it is suitable for input to life cycle assessment. This is the first time this approach has been used at a number of agricultural and forestry sites. We show that agriculture tends to have higher land use impacts than forestry. Those forestry systems that are more intensively managed in shorter rotations have larger land use impacts when calculated for the entire rotation, but this is not the case when land use impact is calculated on the basis of production unit. These findings support the use of landscape mosaics with some high production areas and will be of increasingly significance as we seek to achieve economic growth without environmental degradation. That managed forests have relatively low land use impacts has important implications for forestry restoration and climate mitigation programmes, including the forestry components of Nationally Determined Contributions under the UN Framework Convention on Climate Change.

Comparing different fatigue test methods at asphalt mastic level

Latest research is focused on predicting the fatigue behavior of asphalt mixtures through cost-effective and simple test methods on asphalt mastic level (asphalt binder + mineral fines). There are numerous fatigue test methods for asphalt binders and mastic using the dynamic shear rheometer (DSR). However, up to now, the results of the different fatigue tests on DSR have not been directly compared. Therefore, four different asphalt mastic mixes were prepared, and each was tested with the two most popular fatigue tests [linear amplitude sweep (LAS) test and time sweep (TS) test] and then compared to each other. The TS tests were performed as stress-controlled and as strain-controlled tests. All LAS and TS tests were performed with cylindrical and hyperbolic specimen shapes to identify impact of specimen shape. Different fatigue criteria were applied for evaluation to investigate the comparability of the results. Stress-controlled TS tests, strain-controlled TS tests, and LAS tests reveal different rankings of fatigue performance. However, a dissipated energy approach can combine stress-controlled and strain-controlled TS tests into one fatigue curve. The hyperbolic specimen shape can be used for TS tests and results in the same rankings. The hyperbolic specimen shape is not applicable for LAS tests. A calculation model could be derived to establish a relationship between the measured and actual stresses and strains in the necking of a hyperbolic specimen. TS tests using the dissipated energy approach appear to be the most promising mastic fatigue tests.

Synergistic effect of memory-size-microstructure on thermoelastic damping of a micro-plate

The design of high-performance micro-mechanical resonators requires sufficiently accurate analysis of their thermoelastic damping. In this paper, a micro-resonator is modeled as a thin rectangular plate in vibration, and its thermoelastic damping is characterized in terms of the inverse quality factor Q−1. The Kirchhoff plate theory containing the memory, nonlocal, and size effects is presented, where the memory effect of heat flow is described by a convolution integral for time, its nonlocal effect is captured by the Guyer–Krumhansl model for space and the size effect for microstructures is characterized by Hadjesfandiari and Dargush’s consistent couple stress theory. The temperature field related to the deflection is solved first, and the governing equation of the transverse motion of a vibrating plate is obtained later. Two methods including the complex frequency approach and energy dissipation approach are employed to derive the analytical expression for the inverse quality factor. Emphasis is focused on the synergistic effect of non-locality, memory, and microstructure on the thermoelastic dissipation in micro-plates. Additionally, the influences of boundary conditions, vibration modes, and structural dimension on the thermoelastic damping are also analyzed. The temperature dependence of the thermoelastic damping is predicted and anelastic internal friction is elucidated.

Structural size effect in concrete using a micromorphic stress-based localizing gradient damage model

The presence of a nonlinear fracture process zone (FPZ) plays a crucial role in governing the failure response of a quasi-brittle structure. One such influence is the structural size and boundary effect phenomenon, where the growth and interaction of FPZ with the boundary has a considerable impact on the load-carrying capacity of the structure. In this article, a numerical study is conducted using a micromorphic stress-based localizing gradient damage model [1], recently proposed by the authors, to capture the structural size effect phenomenon during quasi-brittle failure of geometrically similar concrete beams. The main objective is to reproduce the results of independent experimental investigations on the size effect in quasi-brittle structures using a single set of material and numerical parameters. Generally, a quasi-brittle fracture process starts with a diffuse network of microcracks, which eventually localizes in a narrow process zone before forming a macroscopic crack during the final stages of failure. To comply with this description, the micromorphic stress-based localizing gradient damage model incorporates evolving anisotropic nonlocal interactions throughout the loading process through an anisotropic interaction tensor and a damage dependent interaction function. A new arc-length control method based on rates of the internal and dissipated energy approach [2] is modified as per the localizing gradient damage formulation and implemented to trace the nonlinear behavior in numerical simulations. The damage model successfully reproduces the experimental results with localized damage profiles using low-order finite elements for both mode-I and mixed-mode cases.

Numerically Evaluation of FRP-Strengthened Members under Dynamic Impact Loading

Reinforced concrete (RC) members in critical structures, such as bridge piers, high-rise buildings, and offshore facilities, are vulnerable to impact loads throughout their service life. For example, vehicle collisions, accidental loading, or unpredicted attacks could occur. The numerical models presented in this paper are shown to adequately replicate the impact behaviour and damage process of fibre-reinforced polymer (FRP)-strengthened concrete-filled steel tube (CFST) columns and Reinforced Concrete slabs. Validated models are developed using Abaqus/Explicit by reproducing the results obtained from experimental testing on bare CFST and RC slab members. Parameters relating to the FRP and material components are investigated to determine the influence on structural behaviour. The innovative method of using the dissipated energy approach for structural evaluation provides an assessment of the effective use of FRP and material properties to enhance the dynamic response. The outcome of the evaluation, including the geometrical, material, and contact properties modelling, shows that there is an agreement between the numerical and experimental behaviour of the selected concrete members. The experimentation shows that the calibration of the models is a crucial task, which was considered and resulted in matching the force–displacement behaviour and achieving the same maximum impact force and displacement values. Different novel and complicated Finite Element Models were comprehensively developed. The developed numerical models could precisely predict both local and global structural responses in the different reinforced concrete members. The application of the current numerical techniques can be extended to design structural members where there are no reliable practical guidelines on both national and international levels.

Peak Velocity of Viscous Dampers for Direct Displacement Based Design of RC Moment Resisting Frames

ABSTRACT Previous researchers have extended the direct displacement-based design (DDBD) procedure, to design reinforced concrete moment-resisting frame (RC-MRF) buildings with linear viscous dampers (LVDs). In those studies, the viscous damper forces are found to be larger than the design viscous damper forces because the actual relative structural velocity is different from the pseudo-velocity and also due to higher-mode effects. In the present study, a damper velocity correction factor is introduced along the height of the RC-MRF with LVDs, to calculate the corrected velocity of the LVD from the design velocity of the LVD, when the DDBD procedure is used. The damper velocity correction factor is proposed using the results of nonlinear response history analysis (NLRHA) for a set of RC-MRFs with LVDs, which are designed using the DDBD procedure. The DDBD procedure is then used to design RC-MRFs with nonlinear viscous dampers (NLVDs) making use of the proposed damper velocity correction factor, by calculating the NLVD characteristics using the equal energy (EE) dissipation approach or the equal power (EP) consumption approach. The accuracy of the proposed damper velocity correction factor is evaluated by carrying out NLRHA of two sets of RC-MRFs with NLVDs, one set where the damper velocity correction factor is not used, and the other set where it is used. When the damper velocity correction factor is used; the design LVD forces either agree with NLRHA results or are slightly more conservative, the design NLVD forces are close to the NLRHA results, and the maximum value of peak inter-story drift ratio (IDR) along the height of the RC-MRF from NLRHA is close to the design IDR limit. There is no significant difference in the peak story shear forces whether the damper velocity correction factor is used or not.

Asphalt fatigue modeling in constant strain time sweep tests based on dissipated energy approaches

This paper aims to develop asphalt binder fatigue models by time sweep tests under constant strain. By investigating the fatigue life in neat and modified asphalts under linear and nonlinear viscoelastic responses, results were analyzed in terms of strain levels, asphalt type, and additive content. The dissipated energy and dissipated energy ratio concepts were utilized to develop the phenomenological models for estimating fatigue lives of asphalt binders. Results showed that the dissipated energy ratio-based equations give relatively identical fatigue models irrespective of the strain level or asphalt binder type. Moreover, statistical analyses were performed to investigate the contribution of each parameter in the fatigue model prediction. A comparison was made between fatigue life predictions by means of traditional and energy-based methods. Results proved that the fatigue life prediction models based on the concept of dissipated energy ratio follow a similar trend.

Energy Loss in Skimming Flow over Cascade Spillways: Comparison of Artificial Intelligence-Based and Regression Methods

In this study, the energy dissipation of cascade spillways was studied by conducting a series of laboratory experiments. Five spillways slope angles (α) (10°, 20°, 30°, 40°, and 50°), various step numbers (N) ranging from 4 to 75, and a wide range of discharges (Q), were considered. Some data-based models were developed to explain the relationships between hydraulic parameters. Multiple linear and nonlinear regression-based equations were developed based on dimensional analysis theory to compute energy dissipation over cascade spillways. For testing the robustness of developed data-based models, M5P, stochastic M5P, and random forest (RF) were used as new artificial intelligence (AI)-based techniques. To relate the input and output variables of energy dissipation, AI-based and regression approaches were developed. It was found that the formulation based on the stochastic M5P approach in solving energy dissipation problems over cascade spillways is more successful than the other regression and AI-based methods. Sensitivity analysis suggests that spillway slope in degrees (α) is the most influential input variable in predicting the relative energy dissipation (%) of the spillway in comparison to other input variables.