Concept Of Energy Dissipation Research Articles

Seismic performance of RC frame-shear wall dual structural systems

The two structural systems named “functional integration structural systems” and “functional separation structural systems” were proposed based on the design concept of energy dissipation. To study the seismic performance of reinforced concrete (RC) frame-shear wall dual structural systems in which shear walls are used for “functional integration” and “functional separation”, quasi-static tests of two single-story and two-span RC frame-shear wall specimens with a scale of 1:3 were carried out, and numerical simulation analysis of two five-story frame-shear wall dual structures based on the conditional mean spectrum-incremental dynamic analysis (CMS-IDA) method was carried out. The shear walls bearing lateral load and a small part of the vertical load are named functional separation structure. When the shear walls bearing both lateral load and vertical load are named as functional integration structure, the seismic performance was investigated in terms of crack initiation and damage, hysteresis performance, stiffness degradation, energy dissipation capacity, ductility of the specimens, and seismic collapse resistance of the whole structure. The studies showed that when the load-bearing function and lateral resistance function of the shear walls were separated, the structure had better ductility, energy dissipation capacity, damage development process, and seismic collapse resistance.

A generalized model for field assessment of particle settling velocity in a viscoelastic fluid

The accurate prediction of particle settling velocity in viscoelastic fluids is important for the design, analysis, and optimization of various oil-field operations including hole cleaning and cuttings transport in oil and gas well drilling, proppant transport in hydraulic fracturing operations. An experimental study was, therefore, conducted to investigate the effect of fluid viscoelastic properties on the particle settling velocity. The main objectives of the study were to understand the factors that influence the particle settling velocity in shear-thinning viscoelastic fluids and develop a generalized model for the field assessment of particle settling velocity in shear-thinning viscoelastic fluids.We prepared ten different fluids, which were divided into two groups based on their shear viscosity values. In each group, five fluids were having similar shear viscosity and variable elasticity values. Nineteen different spherical particles were used to conduct particle settling experiments with a density range from 2700 kg/m3 to 6000 kg/m3 and a diameter range from 1 mm to 4 mm. Rheological characterizations of the fluids have been conducted by using funnel viscometer, API Rotational viscometer, controlled shear rate, and amplitude sweep test measurements. The fluid elasticity was quantified by using the concept of energy dissipation, which is determined by using standard field measurements of the apparent viscosity (AV) and the funnel viscosity.Finally, based on the experimental results and theory of the particle settling in non-Newtonian fluids, we proposed a model that can be used for predicting particle settling velocity in shear thinning viscoelastic fluids. The statistical analyses have shown that the root means square error and mean absolute percentage error of model predictions were 0.0032 m/s and 4.1%, respectively.

Analysis of damage characteristics of fine and medium‐fine cracked sandstones under a complex stress path

AbstractIn underground engineering such as mining and tunnel excavation, the rock mass is often subjected to repeated loading and unloading stress environments. Herein, true triaxial cyclic loading and unloading tests are carried out on fine sandstone and medium‐fine sandstone specimens with cracks of different angles. The test results show that the mechanical properties of fine sandstone and medium‐fine sandstone samples show obvious differences, and the crack angle has a significant effect on the mechanical properties of the sandstone specimen. During the experimentation, the expansion phenomenon of medium‐fine sandstone is more obvious than that of fine sandstone, and its brittleness is also weaker. The damage law of the sample has nothing to do with the type of sandstone. The damage caused by the stress in the σ1 direction varies linearly with the cumulative damage of the specimen, however, the damage caused by the directions of σ2 and σ3 grow nonlinearly in terms of the cumulative damage of the specimen. The hysteretic loop dissipated energy of the same type of sandstone specimens at different angles are dissimilar, and the dissipated energy increases with the increase of the crack angle. Based on the equivalent irreversible strain and the hysteretic loop dissipated energy, the damage law of the rock strength is analyzed. The obtained results reveal that the index based on the equivalent irreversible strain is helpful in exploring the damage degree of rock in the initial stage of cyclic loading and unloading. Furthermore, the damage index established based on the energy dissipation concept is beneficial to predicting the damage and failure law of rock in the advanced stage of loading.

Analytical Assessment of Reinforced Concrete Frames Equipped with TADAS Dampers

In recent years, it is considerably attempted to develop the concept of energy dissipation as an applicable technology to overcome the energy released by earthquakes. The passive control systems such as metallic dampers have been widely considered. Energy dissipating dampers are used to modify the response of structures as well as to reduce the damages in structure members. This study is conducted to investigate the seismic response of three normal concrete moment resisting frames with 4, 7 and 10 stories equipped with Triangular Added Damping and Stiffness (TADAS) metallic dampers. OpenSees software is employed for nonlinear time-history analysis using seven earthquke records to determine the structure response. The results showed the considerable modifed seismic responses. It is observed that the story drifts are constant and the maximum values in retrofitted 4, 7 and 10 story frames have been decreased 54%, 56% and 55%, respectively. Also, the maximum floor acceleration, the maximum roof displacement and the maximum story shears are lower in the frames equipped with damper and the lateral behavior of the majority of the retrofitted frame members has been upgraded to Immediate Occupancy (IO) and Live Saftey (LS) performance level.

Testing and performance of a new friction damper for seismic vibration control

In the last two decades, great efforts were carried out to reduce the seismic demand on structures through the concept of energy dissipation instead of increasing the stiffness and strength. Several devices based on different energy dissipation principles have been developed and implemented worldwide, however, most of the dissipation devices are usually installed using diagonal braces, which entail certain drawbacks on apertures for circulation, lighting or ventilation and architectural or functional requirements often preclude this type of installations. In this work, a conceptual development of a novel energy dissipation device, called Multiple Friction Damper (MFD), is proposed and examined. To verify its characteristics and performance, the MFD was implemented on a single storey steel frame experimental model and tested under different conditions of normal force and real time acceleration records. Experimental results demonstrated that the new MFD constitutes an effective and reliable alternative to control the structural response in terms of displacement and acceleration. A mathematical formulation based on the Wen's model reflecting the nonlinear behaviour of the device is also presented.

Analytical and experimental investigations into the controlled energy absorption characteristics of thick-walled tubes with circumferential grooves

In this paper, the energy absorption characteristics of grooved circular tubes are investigated under quasi-static loading condition. For experiments, thick-walled tubes with circumferential grooves are prepared. The grooves divide the thick-walled tube into several shorter thin-walled portions. Specimens are subjected to axial crushing load to observe the effect of distribution of circular grooves on the deformation mechanism and energy absorption capacity. Geometrical parameters of the specimens are designed utilizing the Taguchi method to cover a reasonably wide range of groove length-to-wall thickness ratios. An analytical approach based on the concept of energy dissipation through the plastic hinges is applied. Taking the effect of strain hardening into account, the obtained analytical results are in good agreement with the experimental ones. The agreement between analytical and experimental results may indicate the validity of the proposed analytical approach. Desirable mechanism of deformation observed justifies the pre-forming method for obtaining favorable energy absorption characteristics.

Optimal placement of nonlinear hysteretic dampers on planar structures under seismic excitation

In the last twenty years great efforts were carried out to develop the concept of energy dissipation in structures to bring it into an applicable technology. Several devices based on different energy dissipation principles have been developed and implemented worldwide. One of the most important tasks for the designer is to define the locations and sizes of these devices in order to maximize their efficiency and safety. In this work, an efficiently procedure to optimally define the energy dissipation capacity of added nonlinear hysteretic dampers, to meet an expected level of performance on planar structures under seismic excitation is proposed. Knowing that the main contribution to the total uncertainty is due to the excitation and with the aim of achieving a robust design, the excitation is modeled as a stationary stochastic process characterized by a power spectral density compatible with a response spectrum defined by seismic code provisions of the region. Since the analysis is performed in the frequency domain, the nonlinear behavior of dampers is included through stochastic equivalent linearization of Bouc–Wen hysteretic model. The proposed procedure is verified numerically through nonlinear time history analysis using artificial ground motion records.

Hydrodynamics model for gas–liquid stratified flow in horizontal pipes using minimum dissipated energy concept

A new hydrodynamics model is proposed using minimum energy dissipation concept for gas–liquid stratified flow in horizontal pipes. It determines the liquid holdup and the pressure drop in gas–liquid stratified flow without the need of interfacial friction factor closure relationship. Model predictions show fair agreement when compared with experimental data and existing mechanistic models. • A new minimum energy dissipation concept to characterize gas–liquid stratified flow. • Hydrodynamics model without combined momentum equation and interfacial friction factor. • Improvement of previous empirical correlations on estimating flow characteristics. • Reliable prediction of liquid holdup and pressure gradient.

Effect of low density, low strength polyurethane foam on the energy absorption characteristics of circumferentially grooved thick-walled circular tubes

In this paper, analytical and experimental investigations are performed on the energy absorption characteristics of circumferentially grooved thick-walled circular tubes filled with low density and very low strength polyurethane foam typical of cushioning material. Thick-walled grooved tubes filled with low density foam are prepared for experiments. The results are also compared with the ones for the geometrically identical empty tubes. Employing the Taguchi method for designing the geometrical parameters of the specimens leads to a suitable range of groove length-to-wall thickness ratios to be covered. Based on the concept of energy dissipation through the circumferential plastic hinges during the successive folding of the specimens, an analytical approach is proposed. In addition, the amount of energy dissipated due to the interaction between tube metal and foam material is expressed by a conventional semi-empirical equation. A new constant, Cav, for low strength foam material is found by fitting the experimental data. The modified analytical model is in reasonable agreement with the experiments. This may indicate the validity of the proposed analytical model. The obtained results show that grooved thick-walled tubes filled with low strength foams can offer favorable energy absorption capacity and stability. Euler buckling is prevented due to the grooves and specific energy absorption is increased approximately twice that of the empty tubes. Structural effectiveness is increased nearly two times that of the empty tubes.

A new variable stiffness suspension system: passive case

Abstract. This paper presents the design, analysis, and experimental validation of the passive case of a variable stiffness suspension system. The central concept is based on a recently designed variable stiffness mechanism. It consists of a horizontal control strut and a vertical strut. The main idea is to vary the load transfer ratio by moving the location of the point of attachment of the vertical strut to the car body. This movement is controlled passively using the horizontal strut. The system is analyzed using an L2-gain analysis based on the concept of energy dissipation. The analyses, simulation, and experimental results show that the variable stiffness suspension achieves better performance than the constant stiffness counterpart. The performance criteria used are; ride comfort, characterized by the car body acceleration, suspension deflection, and road holding, characterized by tire deflection.

Critical currents in graphene ribbon Josephson's junctions

The rapidly advancing technology of nanodevices has led to the production of smaller and smaller structures often called mesoscopic systems. These devices are large on the atomic scale, but sufficiently small that the electron wave function is coherent over the entire sample: the condition for coherence is that the electron traverses the wire without undergoing any collision with phonons or other electrons. Because the electron can lose energy and equilibrate with heat bath only via inelastic collisions, it is necessary to re-examine the conventional concept of energy dissipation in a resistor. We study the way in which the superconducting correlations are induced in graphene ribbon when it is placed between two superconductors, how such correlations may depend on complex edge structure of the ribbon, on the geometry of the experimental set-up and what is the role of Andreev's reflection in Josephson's effect at superconducting contacts.

Dynamic mechanical characterization of asphalt concrete mixes with modified asphalt binders

The primary objective of this work is to characterize and compare the dynamic mechanical behavior of asphalt concrete mixes with styrene butadiene styrene (SBS) polymer and crumb rubber modified asphalt binders with the behavior of mixes with unmodified viscosity grade asphalt binders. Asphalt binders are characterized for their physical and rheological properties. Simple performance tests like dynamic modulus, dynamic and static creep tests are carried out at varying temperatures and time. Dynamic modulus master curves constructed using numerical optimization technique is used to explain the time and temperature dependency of modified and unmodified asphalt binder mixes. Creep parameters estimated through regression analysis explained the permanent deformation characteristics of asphalt concrete mixes. From the dynamic mechanical characterization studies, it is found that asphalt concrete mixes with SBS polymer modified asphalt binder showed significantly higher values of dynamic modulus and reduced rate of deformation at higher temperatures when compared to asphalt concrete mixes with crumb rubber and unmodified asphalt binders. From the concept of energy dissipation, it is found that SBS polymer modification substantially reduces the energy loss at higher temperatures. Multi-factorial analysis of variance carried out using generalized liner model showed that temperature, frequency and asphalt binder type significant influences the mechanical response of asphalt concrete mixes. The mechanical response of SBS polymer modified asphalt binders are significantly correlated with the rutting resistance of asphalt concrete mixes.

Algorithmic issues for three-invariant hyperplastic Critical State models

Implicit stress integration and the consistent tangents are presented for Critical State hyperplasticity models which include a dependence on the third invariant of stress. An elliptical deviatoric yielding criterion [43] is incorporated within the family of geotechnical models first proposed by Collins and Hilder [8]. An alternative expression for the yield function is proposed and the consequences of different forms of that function are revealed in terms of the stability and efficiency of the stress return algorithm. Errors associated with the integration scheme are presented. It is shown how calibration of the two new material constants is achieved through examining one-dimesional consolidation tests and undrained triaxial compression data. Material point simulations of drained triaxial compression tests are then compared with established experimental results. Strain probe analyses are used to demonstrate the concepts of energy dissipation and stored plastic work along with the robustness of the integration method. Over twenty finite element boundary value problems are then simulated. These include single three-dimensional element tests, plane strain footing analyses and cavity expansion tests. The rapid convergence of the global Newton–Raphson procedure using the consistent tangent is demonstrated in small strain and finite deformation simulations.

Static and Dynamic Three-Dimensional Finite Element Analysis of Pelvic Bone

The complex shape of the human pelvic bone was successfully imaged and modeled using finite element FE processing. The bone was subjected to quasi-static and dynamic loading conditions simulating the effect of both weight gain and impact. Loads varying between 500 - 2500 N (~50 - 250 Kg of weight) was used to simulate 3D quasi-static weight gain. Two different 3D dynamic analyses, body free fall at two different heights (1 and 2 m) and forced side impact at two different velocities (20 and 40 Km/hr) were also studied. The computed resulted stresses were compared for the four loading cases, where Von Misses stresses increases linearly with the weight gain increase under quasi-static loading. For the dynamic models, the Von Misses stress history behaviors were studied for the affected area and effected load with respect to time. The normalization Von Misses stresses with respect to the applied load were used for comparing the free fall and the forced impact load results. It was found that under the forced impact loading condition an over lapping behavior was noticed, where as for the free fall the normalized Von Misses stresses behavior was found to nonlinearly different. This phenomenon was explained through the energy dissipation concept. This study will help designers in different specialization in defining the weakest spots for designing different supporting systems.

2-D analytical model for characterizing flexural damping responses of composite laminates

Abstract The flexural damping behaviors of composite laminates were characterized analytically in this study. A 2-D analytical model was developed based on the extension of Ni–Adams model [Ni RG, Adams RD. The damping and dynamic moduli of symmetric laminated composite beams—theoretical and experimental results. J Compos Mater 1984;18(2):104–21] accounting for the energy dissipation contributed by the laminar stresses of σxy and σyy. The specific damping capacity (SDC) of the composite was determined in accordance with the energy dissipation concept, which was defined as the ratio of the dissipated energy to the stored energy for per circle of vibration. The 2-D analytical model was validated by comparing the SDC of [0/−60/60]s and [0/90/45/−45]s laminates with the experimental data and the finite element (FEM) results. In addition, the effects of interlaminar stress on the flexural damping responses of laminated plates were also characterized in the 3-D FEM analysis. Results indicated that the interlaminar stress effect may not be so significant that the current 2-D model is adequate for the evaluation of the damping responses of the composite laminates. Furthermore, the present predictions, as compared to the Ni–Adams [Ni RG, Adams RD. The damping and dynamic moduli of symmetric laminated composite beams—theoretical and experimental results. J Compos Mater 1984;18(2):104–21] and Adams–Maheri [Adams RD, Maheri MR. Dynamic flexural properties of anisotropic fibrous composite beams. Compos Sci Technol 1994;50(4):497–514] models, generally demonstrate good agreements with the experimental data and the FEM results.

Effect of fiber array on damping behaviors of fiber composites

This study aims to investigate the fiber array effect on modal damping behaviors of fiber composites. Three different fiber arrays, i.e., square edge packing (SEP), square diagonal packing (SDP), and hexagonal packing (HP), were considered to represent the microstructures of the unidirectional composites. Repeating unit cells (RUCs) suitable for describing the characteristics of the microstructure were adopted in the generalized method of cell (GMC) micromechanical analysis. The energy dissipation concept was then employed to calculate the specific damping capacities of composites in the material principal directions. The specific damping capacities obtained from micromechanical analysis were regarded as the equivalent damping properties homogenizing in the composites. In conjunction with the modal shapes of the composite structures determined from the finite element analysis, the specific damping capacity was extended to characterize the corresponding modal damping of the composite rods and plates. Both free–free and clamped-free boundary conditions were taken into account in the composite structures. Results indicated that the structures constructed from the composites with SDP fibers exhibit better damping behaviors than the other two cases.

Integrated debris flow disaster mitigation

Integrated disaster mitigation needs interpreting torrent catchment areas as complex landscape systems. The history of valley-evolution shows the influence of climate and vegetation on the valley-evolution. The energy-concept (energy dissipation concept including the idea of the energy-line) is used for a simple explanation of debris flow. Examples of heavy debris flow disasters in controlled torrents in the Alps and Pyrenees give hints, which expanding the time scale can show that side-effects restrict or counteract the mitigation measures. A pallet of different mitigation measures to avoid or to reduce some of the side-effects is shown. The comprehensive method of disaster mitigation also includes the effect of vegetation. The pallet includes: avoiding hazards (hazard mapping, warning and alarming), appropriate land use and avoiding disaster-enhancing measures in the landscape and technical measures, which take into account their side-effects. The energy line is used as simple design theory. The Jiu-Jitsu Principle is explained too. With this comprehensive method a more sustainable reduction of disasters seems possible.

Effect of Static Interaction on Vertical Vibration of Pile

An approximate numerical procedure to compute the vertical response of a vertical pile in a linearly elastic homogeneous soil medium in the time domain is presented. The approach combines Novak's concept of energy dissipation through radiation damping and Poulos' concept of pile-soil-pile interaction based on the Mindlin elastic solution. The predictions are assessed against two experimental studies. This time domain approach has the potential to consider nonlinear soil behavior, discontinuity conditions at the pile-soil interface, and pile-soil slip. The most significant promise of this scheme is to predict the propagation of vibration along the ground surface, generated from the vibration of the pile.

Micromechanical deformation processes in toughened and particle filled semicrystalline polymers: Part 2. model representation for micromechanical deformation processes

Toughening mechanisms occurring in various toughened and particle filled semicrystalline polymers have been investigated by several cursive electron microscopic techniques. In the previous work (Part I) it has been shown that the toughening mechanisms involved in different blend systems are influenced decisively by the phase morphology of modifier particles and the phase adhesion between matrix and modifier particles, which in turn lead to different micromechanical deformation processes. Form these results six different schematic models for micromechanical deformation processes are proposed. To simplify the explanation of micromechanical deformation processes it has been described in form of three-stage-mechanism. Finally, the results of micromechanical deformation processes are discussed with the concept of energy dissipation and stress states.

Microstructural response of mono- and multilayer hard coatings during indentation microhardness testing

An investigation of indentation crack patterns and the nature of fracture mechanisms of hard coatings can provide useful information to aid in the understanding of failure mechanisms occurring as a result of scratch and wear tests. Examples of several different types of single and multilayer coating systems are presented in this study. The effect of substrate and microstructure on the brittle-ductile transition behaviour is discussed. The concept of energy dissipation is introduced to interpret deformation and fracture behaviour during indentation tests. If a hard coating undergoes some densification or plastic flow to dissipate a proportion of the energy, then the premature adhesive failure due to the non-compliance of the strain at hard coating/substrate interface can be avoided. The compaction or plastic flow of the hard coating also effectively disperses concentrated stress and delays the formation tensile cracks around indentations.