Energy Dissipation Zone Research Articles

Seismic performance of high-rise shear wall with concealed truss under high axial force ratio

In this paper, the high-rise shear wall with a concealed truss was proposed for improving seismic performance. Reinforcing bar truss and steel truss were used in the proposed shear walls. The innovative composite shear wall incorporates two combinations, i.e., one involving two load-bearing systems, including a truss and shear wall, while the other combines steel and concrete as distinct materials. Five specimens with different structural forms were tested under cyclic loading tests. The resulting failure characteristics, hysteretic performance, strength, deformation, energy dissipation capacity, stiffness, and strain characteristics were studied. The influence of various structural forms on the seismic performance of shear walls under the high axial force ratio was also analyzed. The results showed stable hysteresis curves for the innovative shear walls. Also, it was found that the high-rise shear walls with concealed trusses effectively control crack propagation compared to conventional high-rise shear walls. The proposed walls exhibited a uniform and broader crack distribution. Concealed trusses in the high-rise shear walls enhanced the plastic energy dissipation zone at the base, improving the corresponding energy dissipation capacity. Using different types of trusses did not exhibit any significant difference in the resulting seismic performance. Finally, an evaluation method for the ultimate strength and stiffness of the shear walls with concealed trusses was proposed and validated.

Overstrength and plastic rotation of two-segment replaceable link with separated splicing plate

To enhance the seismic performance and post-earthquake reparability of traditional eccentrically braced frame structures, this study proposes a two-segment replaceable links with separated splicing plate: one featuring specimens with standard holes in the separated splicing plate (TSRL1), and the other featuring specimens with slotted holes in the separated splicing plate (TSRL2). Through cyclic loading tests, it was observed that the hysteresis curves of the links exhibited a relatively complete response, characterized by plastic rotations of 0.09 rad and 0.17 rad respectively. The overstrength coefficient ranged from 1.66 to 2.08, indicating commendable performance in terms of both overstrength and plastic deformation capacity. Subsequently, finite element simulations of the link were conducted using ABAQUS. Based on the congruity between simulation and test results, a parametric analysis was performed to determine the optimal seismic performance of the two-segment replaceable links with separated splicing plate by varying the length of the energy dissipation zone and hole type of the bolts.

The fracture failure modelling of three-dimensional structures composed of quasi-brittle materials subjected to different loading velocities rates by the dipole-based BEM approach

This study presents a numerical formulation for representing the fracture-failure of three dimensional structures composed of quasi-brittle materials. In addition to the nonlinear nature of quasi-brittle fracture, the formulation accounts the mechanical effects of different loading velocities rates. Therefore, these developments enable the modelling of viscous-cohesive fracture processes. The Boundary Element Method (BEM) describes the mechanical fields by the dipole-based approach, which has been extended to the three dimensional problems herein. This BEM approach is effective in crack growth modelling because only one crack surface requires discretisation. The classical cohesive crack approach models the material resistance at the energy dissipation zone surrounding the crack front. Besides, a time dependent function updates the cohesive crack approach and incorporates the viscous behaviour by modifying the tensile material strength and the material fracture energy as a function of the loading velocity rate. Three applications demonstrate the adequate performance of the proposed formulation, in which the results obtained have been compared against analytical and experimental responses available in the literature.

The influence of phase morphology of polycarbonate/polyethersulfone blends on the failure behavior between the blends and polyurethane in the peel test

AbstractIn peel, tests between polycarbonate/polyethersulfone (PC/PES) blends with different compositions and thermoplastic polyurethane (TPU) films with different thicknesses a large decrease in energy release rate is observed when the PC/PES blends formed a co‐continuous structure. With SEM analysis, XRD measurements, selective PC etching of failed samples, and finite element modeling of the stress distributions in the co‐continuous region this fracture behavior can be explained. It is caused by the interplay between the formation of the main crack in the process zone and the size and density of microcracks in the energy dissipation zone. While the pure components PC and PES exhibit good adhesion to the TPU, the immiscibility of PC and PES causes the steady decrease of with increasing volume fraction of the minor phase.

Hydrodynamic performance of submerged breakwater in tandem with thin-walled as submerged reef structure

The interaction of gravity waves with submerged tandem breakwater of different structural configurations is analysed in finite water depth using the Multi-Domain Boundary Element Method (MDBEM). The wave transformation characteristics, wave forces and wave energy dissipation are analysed considering the presence of impermeable type thin-walled as reef structure in front of the primary submerged breakwater. The comparative study is performed for the submerged structures of various shapes (trapezoidal, triangular, rectangular and thin-walled) and types (rubble mound, permeable, impermeable) that are designed to function together as a tandem breakwater. The effect of varying angle of incidence, relative submergence depth, and relative gap between the reef structure and primary breakwater on wave reflection and transmission are derived for the suggested tandem breakwater models. Among all the impermeable-type models, the thin-walled as reef structure designed at a distance in front of thin-walled as a primary submerged breakwater as a tandem is observed to perform efficiently in terms of energy dissipation and also offers an optimum wave transmission for both short and long wave conditions. Further, the permeable and rubble mound type trapezoidal tandem breakwater offers higher energy dissipation in comparison with all other breakwaters. In view of the design considerations and structural stability of submerged breakwaters, the addition of a reef structure acts as a defence system for the primary breakwater and also creates an energy dissipation zone that allows the shore dynamics to be preserved, making tandem models more effective in the harbour region.

45 YEARS OF DELIBERATIONS ON THE THERMO-MECHANICAL INTERPRETATION OF FRICTION AND WEAR PART I – THE MACROSCOPIC INTERPRETATION OF THE TRIBOLOGICAL PROCESS

This first part will consider the friction couple or its part, identified with the open thermodynamic system. Dependences among extensive parameters and energetic interactions in the system and its boundaries with the environment are described in analytical terms. The dimensions of the energy dissipation zone, where the friction of solids takes place, are established. The thermo-mechanical nature of the tribological process is demonstrated. The wear conditions and distribution of energy generated by its particular elements are determined. A new quantity is introduced – the specific work of wear, which characterises the wear resistance of the tribological system and its parts. The effect of the reciprocal cover of solids’ friction surfaces on the energy balance structure in calorimetric testing is analysed. The concept of generalised wear is introduced and standardised. The discussion is restricted to processes at the macroscopic level of matter organisation.

NATURAL FEATURES AND HYPOTHESES OF ORIGIN NEASHORE BARS IN THE COASTAL ZONE OF NON-TIDAL SEAS

Problems of the research. The article considers the origin, morphology and dynamics of unique forms of coastal-marine relief in the coastal zone of non-tidal seas, under the influence of the hydrogen factor, an exceptionally strong potential of mechanical energy, sufficiently large reserves of sand deposits (fractions of 0.05–1.00 mm), active influence of wave impulses and wave currents in the zone of energy dissipation, active nanoexchange between the shore and the underwater slope. It is shown that this issue has a long history of scientific research in different countries due to its important practical significance. Long years we researching the alongshore sand drifting between C. Bol. Fontain in North to Jebriyan Bay in South as a experimental natural object of the North-Western part of the Black Sea. Theoretical elaborations and methods. Among the natural features of the named landforms, the researchers distinguish 8 leading ones, which are manifested only in the environment of the coastal zone. Therefore, the purpose of the article is to consider the genetic hypotheses of the formation of underwater sand bars in the coastal zone of the seas over the past 100 years, and on this basis – to outline, evaluate, analyze several hypotheses about the formation of bars, show their positives and disadvantages, name the genetic features for the physical geographical. coastal environments As part of the eight most important and most common features, we have identified the following: distribution of wind wave sizes and wave current velocities; the value of the steepness of the underwater slope covered with sediments; value of sediment sizes and hydraulic value of coastal zone sediments; some processes of wave transformation and dispersion of wave energy; certain individual processes of sediment movement of different hydraulic magnitudes in a cell of a sandy coastal zone; steepness of wind waves during storms in the spray source; active action of sand drifts by movement along the coastline and under the influence of the regime of transverse sediments; the nature of underwater swells is different, because one of them moves from the underwater slope to the shore, another – from the shore towards the sea, and the third is dynamically stable. Main results and conclusions. As can be seen, the main hypotheses and the corresponding features of the formation of underwater swells act on their own, separately from the general process of development of the coastal zone of the seas. Such a principle does not meet the elementary requirements for the definition and evaluation of complex geographic natural systems. This is especially true for the coastal zone of the seas, where all the genetic components of the continental, oceanic, and coastal-marine types interact closely in a complex. They act unanimously. It is from such positions, according to this principle, that underwater sand bars and other coastal-marine landforms should be investigated. In other elements of the exogenous part of the geographic envelope, they are not found anywhere and determine the uniqueness of the coastal zone of the seas. The authors of these variants build their hypotheses on separate parts of natural coastal phenomena. Until now, researchers have avoided complex, systematic approaches to this topic. Therefore, the article provides recommendations for improving the theory of the genesis and development of underwater swells within different sites of alongshore sand drifting.

SOME COMMENTS ON THE INTERPRETATION OF THE TRIBOLOGICAL WEAR COEFFICIENT

An original model of tribological wear is presented, an alternative to the commonly used J.F. Archard’s model. The impossibility is established of a full conversion of mechanical work into the heat of dissipation and thereby of avoiding wear in the sliding friction of solids. The assumption is consequently questioned that only some contacts of surface asperities are subject to temporary wear. Material wastage is assumed to occur at each contact of asperities. The volume of worn material is dependent on the volumetric wear coefficient of the “energy dissipation zone” in friction. The dimensions of the zone are determined in both the elements in friction. Linear wear intensities and volumetric wear are described in analytical terms. The thermodynamic analysis of the tribological process indicates some limitations to these intensities. Energetic efficiencies of solid wear and heating as a result of friction are defined. Some new interpretations of the wear coefficient are proposed.

Revisiting the Origins of the Fracture Energy of Tough Double-Network Hydrogels with Quantitative Mechanochemical Characterization of the Damage Zone

The high fracture energy of tough soft materials can be attributed to the large energy dissipation zone around the crack tip. Hence, quantitative characterization of energy dissipation is the key t...

Switchable adhesion between hydrogels by wrinkling

On-demand adhere to and detach from soft and wet surfaces are crucial for hydrogels for applications in tissue engineering, soft machines, and soft robotics. Whereas strong adhesion has been achieved between hydrogels, on-demand switching from strong adhesion to weak adhesion for benign detachment is still under explorations. Herein, we report an approach for switchable adhesion between hydrogels by invoking a mechanical process, wrinkling. The approach is demonstrated by bonding two hydrogel adherends with a wrinkled hydrogel adhesive, with the formation and characterizations of wrinkles tailored by regulating the prestretch of adherend and optimizing the ingredients of adhesive synergistically. On one hand, the formation of wrinkles enhances adhesion by creating a tortuous path for crack propagation and an extended energy dissipation zone. The resulting adhesion is robust to elicit bulk dissipation within the adherend and transform the once adhesive failure to cohesive failure. On the other hand, the suppression of wrinkles deactivates the adhesion enhancement mechanism to facilitate effortless debonding. As a proof-of-concept, a hydrogel patch that can strongly adhere to a damaged hydrogel device for repair and gently detach after repairing, based on the switchable hydrogel adhesion, is demonstrated. The proposed method expands the design space for hydrogel adhesion.

Crack Tip Field of a Double-Network Gel: Visualization of Covalent Bond Scission through Mechanoradical Polymerization

Quantitative characterization of the energy dissipation zone around a crack tip is the focal point in the fracture mechanics of soft materials. In this report, we present a mechanochemical techniqu...

Seismic Performance of Steel Box Bridge Piers with Earthquake‐Resilient Function

A novel steel box bridge pier with replaceable energy dissipation wall plates at the base was proposed. After moderate earthquakes, the damaged energy dissipation wall plates and constraining steel plates on the two sides could be rapidly replaced, while the entire energy‐dissipated column at the base can also be replaced after rare earthquakes. In this way, the seismic capacity of the new type of steel box bridge pier could be restored after earthquakes. For the purpose of discussing the seismic performance of this novel steel box‐shaped bridge pier, the pseudostatic test and numerical simulation were performed. The results showed that the failure of the specimens in the pseudostatic tests occurred predominantly in the energy dissipation zone at the base. After replacing the damaged energy‐dissipated column at the base, the seismic behavior of the proposed steel bridge pier can be recovered rapidly. Axial compression ratio is an important factor influencing the seismic behavior of the novel steel box bridge pier. The strength of the energy dissipation wall plates influences the novel steel box‐shaped bridge pier’s bearing capacity and deformation capacity. Spacing between the horizontal stiffening ribs had little impact on the bearing capacity and deformation capacity of the proposed steel bridge pier. The larger the thickness of the energy dissipation wall plate, the higher the bearing capacity and deformation capacity of the steel box bridge pier. Finally, an empirical equation for the design of this novel steel bridge pier under cyclic loading was proposed.

Tough and tunable adhesion of hydrogels: experiments and models

As polymer networks infiltrated with water, hydrogels are major constituents of animal and plant bodies and have diverse engineering applications. While natural hydrogels can robustly adhere to other biological materials, such as bonding of tendons and cartilage on bones and adhesive plaques of mussels, it is challenging to achieve such tough adhesions between synthetic hydrogels and engineering materials. Recent experiments show that chemically anchoring long-chain polymer networks of tough synthetic hydrogels on solid surfaces create adhesions tougher than their natural counterparts, but the underlying mechanism has not been well understood. It is also challenging to tune systematically the adhesion of hydrogels on solids. Here, we provide a quantitative understanding of the mechanism for tough adhesions of hydrogels on solid materials via a combination of experiments, theory, and numerical simulations. Using a coupled cohesive-zone and Mullins-effect model validated by experiments, we reveal the interplays of intrinsic work of adhesion, interfacial strength, and energy dissipation in bulk hydrogels in order to achieve tough adhesions. We further show that hydrogel adhesion can be systematically tuned by tailoring the hydrogel geometry and silanization time of solid substrates, corresponding to the control of energy dissipation zone and intrinsic work of adhesion, respectively. The current work further provides a theoretical foundation for rational design of future biocompatible and underwater adhesives.

Enhancement of ductility of steel moment connections with noncompact beam web

A simple method of welding longitudinal stiffeners (LSs) in the beam web within plastic energy dissipation zone is proposed here to enhance the ductility of beam-to-column connections with noncompact beam web. In this study, a series of cyclic loading experiments on full-scale beam-to-column subassemblies demonstrating weak-beam-strong-panel characteristics, designed using the proposed connection method, were conducted to examine their seismic resistance characteristics. Attention was mainly focused on the ductility and energy dissipation capacity of beams itself. Test results show that the presence of the LSs is effective in deferring the local buckling of the beam web. The proposed connection method is preferred to enhance ductility of steel moment connections with noncompact beam web in terms of both economic efficiency and fabrication convenience. Parametric studies through simplified finite element models verified by tests were furthermore carried out to clarify the effects of main parameters on the ductility enhancement of steel moment connections. With the increase in the flexural rigidity ratio of the LSs to beam web, the ductility is found to be improved. It is also found that the minimum required flexural rigidity recommended by AASHTO can guarantee good ductility for stiffened connections with the slenderness ratio of beam web less than 130 when sustaining cyclic bending.

Wave transformation on a sub-horizontal shore platform, Tatapouri, North Island, New Zealand

Waves are generally considered to be an important control on shore platform evolution but there have been very few detailed studies of wave dynamics on rocky coasts. This study provides a detailed description of wave transformation processes across a shore platform near Gisborne, New Zealand. A field experiment was conducted on an intertidal, 250 m-wide platform that is characterised by a sharp seaward edge. Mean platform elevation is 0.7 m below mean sea-level (MSL) and platform gradient is 0.3°. Four nearly equally spaced pressure gauges were deployed over a 24-h period during fair-weather swell conditions characterised by a mean wave height of 0.4–0.5 m and wave period of 7 s. Wave energy at the seaward edge of the platform was dominated by incident swell waves with peak frequency at 0.09 Hz. At all tidal stages waves broke at the seaward edge of the platform, but changing tidal stage exerted a strong control on the rate of wave energy attenuation across the platform. The relative importance of waves at wind-wave frequencies increased in the centre of the platform as the tidal stage and water level increased, whereas infragravity waves became dominant toward the cliff toe. Three different hydrodynamic zones were distinguished across the shore platform; (i) a breaker zone close to the seaward edge; (ii) a propagation/shoaling zone in the central region of the platform; and (iii) a zone of energy dissipation across the inner part of the platform. The spatial dimensions of the three zones varied with changing tidal stage, enabling different wave processes to operate across different parts of the platform at different times. The experiment showed that wave-height attenuation is strongly controlled by tidal stage, ranging between 93% attenuation of wave height during the initial flooding stage to 44% attenuation at high tide. Wave height was found to be depth-limited, with the ratios of H max and H m0 to water depth calculated as 0.7 and 0.4, respectively. The findings imply that platform geometry has an important influence on wave processes on shore platforms. The geomorphic implications of gravity and infragravity waves are discussed.

2-D NUMERICAL WAVE FLUME WITH SOLID-GAS-LIQUID INTERACTION AND ITS APPLICATION

A 2-D numerical wave flume based on a multiphase flow model with solid-gas-liquid interaction is presented in this paper. The governing equations are divided into an advection step and a non-advection step by making use of a time splitting method. A CIP method is used to calculate the hyperbolic equations for velocity and pressure at the advection step, while equations at the non-advection step are solved with an extended SMAC method. Conservation equation of mass is directly solved by using a CIP-CSL2 method. A non-reflective wave generator employing a source/sink method for wave generation and an energy dissipation zone are utilized to realize the numerical wave flume. Besides, the constitutive laws of the non-Newtonian fluid are taken into account to make the model capable of simulating the behavior of Bingham fluid. The validity and utility of the numerical wave flume are demonstrated by applying it to wave breaking and post-breaking wave deformation on the slope, the dynamic motion of a floating body under wave action and the collapse of the Bingham fluid column with multiple rigid bodies.

Influence of microstructure and deformation behavior on toughening of reactively compatibilized polyamide 6 and poly(ethylene-co-butyl acrylate) blends

Influence of microstructure on impact toughness and fracture behavior of PA6 and EBA blends reactively compatibilized by EBA-g-MAH was quantitatively studied. The reactively compatibilized blends showed better distribution of elastomeric EBA particles in the PA6 matrix and the presence of EBA-g-MAH resulted in considerable reduction of interfacial tension between the component polymers. The interfacial adhesion between the PA6 and EBA phase in the compatibilized blends was enhanced by the interfacial reaction between the amide end-groups of PA6 and maleic anhydride group of EBA-g-MAH compared to uncompatibilized blends. The matrix ligament thickness and particle diameter values were lower than the predicted critical values and were responsible for the ductile behavior of the compatibilized blends. Stress whitening around the notch occurred in all the compatibilized blends which was the major energy dissipation zone in the blends. Matrix shear yielding or plastic flow without crazing was the dominant deformation mechanism in the tough compatibilized blends. There was no sign of shear yielding during impact fracture of the uncompatibilized blends where the elastomeric particles were completely dislodged from the matrix.

Fatigue crack propagation and damage evolution in PBT‐GF and SAN‐GF

AbstractOur earlier investigations of fatigue behavior in PBT‐GF and SAN‐GF with different fiber lengths have shown that fatigue crack propagation (FCP) can be described in terms of elastic‐plastic fracture mechanics. In this work it is shown that the influence of structural material parameters on the resistance to FCP correlates with the extent of energy dissipation at the crack tip. With increasing fiber length, the zone of energy dissipation is increased. By means of microscopic investigations, the prevailing damage in the zone of energy dissipation is identified as micro cracks in the matrix.

Estimation of energy-dissipative process development during crack propagation in an intermetallic alloy

A technique based on the non-linear energy principles of fracture for evaluation of the elastic and irreversible constituents of the crack growth resistance is described. These contributions were determined for two Ni3Al-based cast alloys. It was shown that the irreversible part of the crack propagation resistance goes through a maximum with the crack increment, while the linear elastic constituent is generally constant. An alloy containing Cu develops an energy dissipation zone to a greater extent than does an Mo-doped alloy.

Influence of particle-size distribution of particles being sintered on the crack resistance of a porous ceramic

The author assess the influence of grain size and temperature on the fracture properties of a zirconium dioxide ceramic and determine that there are at least three effects leading to an increase in crack resistance with the addition of coarse particles to a matrix of fine particles: an increase in the area of the fracture surface; rounding by the crack of the filler particles accompanied by a change in orientation of the crack relative to the direction of action of the maximum tensile stresses; and the formation and development of a zone of energy dissipation ahead of the main crack front. The relative contribution of each of these effects is evaluated.