Energy Dissipation Ratio Research Articles

Unique framework effect induced by uniform silk fibroin dynamic nanospheres enables multiscale hydrogel with outstanding elastic resilience and strain sensing performance

It is a significant challenge to obtain hydrogels simultaneously with low tensile energy dissipation, high compressive resilience and long durability. Herein, the uniform dynamic nanospheres (Sil-4H0.75) derived from 4-Hydroxybutyl acrylate glycidyl ether grafted silk fibroin is designed to overcome this issue. Due to its uniform and dynamic characteristic, Sil-4H0.75 could endow hydrogel with homogeneous multiscale structure and produce unique framework effect. Thus, transparent Sil-4H0.75 crosslinked acrylamide hydrogel doped with Ag nanowires APS3.75%/AgNW0.1 exhibits a high stretchability (1260 %) and outstanding elastic resilience. The tensile energy dissipation ratio maintains a low value of 9 % across a wide 800 % strain range. A high compression resilience ratio of 92.2 % is kept after ten compression cycles under 90 % compressive strain. The orderly AgNWs motion guided by framework effect also make it be used as both tensile and compressive sensors and exhibits high gauge factor of 7.35, outstanding compression sensitivity of 30.379 kPa−1 and excellent durability (up to 2000 cycles). The detection or other applications based on both two sensing modes are also demonstrated. In a word, this work affords a general strategy to achieve high-performance hydrogel based on uniform dynamic nanospheres which exhibits great potential in the applications of flexible wearable strain sensors.

Characteristics of flow passing over Hydrofoil Crested Stepped Spillway

A spillway comprises several sections, primarily the crest and chute, essential for safe water flow from an upstream reservoir to a downstream river. Incorporating a hydrofoil crest and stepped chute features creates an efficient Hydrofoil-Crested Stepped Spillway (HCSS). The hydraulic features of the 60 HCSS models, which were designed through the National Advisory Committee for Aeronautics (NACA) equation, are assessed through laboratory experiments under a skimming flow regime, where the five hydrofoil formation indexes (t), three numbers of steps (Ns), and four chute angles (θ) are of concern. The findings indicate that an escalation in the ratio of upstream depth (yup) to spillway height (P), correlates with a rise in the discharge coefficient (Cd) in HCSSs. Furthermore, augmenting the t effectively boosts the Cd value. On average, the Cd value of the crest at t = 1 surpasses that at t = 0.2 by 20 %. This increase in t accentuates the curvature of the spillway crest, thereby enhancing the curvature of streamlines and reducing the flow distance therein. The Energy Dissipation Ratio (EDR) of HCSS is influenced by factors such as t (positively correlated), Ns (positively correlated), and θ (negatively correlated). Optimal performance of the HCSS is observed at t = 1, where both the Cd and EDR reach their peak values.

The Effect of Tailwater on the USBR Type III Stilling Basin Model

This study evaluates the impact of tailwater on the USBR Type III stilling pond model, which is often used to construct reservoirs with low hydrostatic pressure and small flow rates. The model includes channel blocks, barrier blocks, and end barriers to dampen energy, converting flow from supercritical to subcritical. Hydraulic characteristics, including potential jump types, pressure regimes, and forces on the barrier, are not considered. Any change in discharge during the test also changes the tailwater depth position. The purpose of this study was to determine the effects of tailwater conditions on water height (y1 and y2), pool length (Lj), Froude number (Fr), critical depth (yc), and energy dissipation effectiveness (ΔE). This study shows that the average energy dissipation ratio of USBR Type III Quiet Pool is 87.45% without the effect of Tailwater, with an efficiency rate of 12.55%. When exposed to Tailwater, the average energy dissipation ratio drops to 69.47%, resulting in an efficiency rate of 30.53%. The optimum stilling pond performance is affected by the presence of tailwater (Tw), which reduces the energy dissipation ratio. The depth of the tailwater aids in the dissipation that occurs. Technical abbreviations will be explained in the first use. The water level rise under tailwater conditions exceeds that without tailwater. This finding shows tail water's importance for height rise and flow conditions. Flow conditions with Froude Number (Fr2) values of 0.22 (<1) and Tw are classified as subcritical flow.

Damage characteristics and constitutive model of magnesium slag-based cemented backfill based on energy dissipation

Uniaxial compression tests were conducted on magnesium slag-based backfill with different curing ages (3, 7, and 28 d) and different magnesium slag grinding time (0, 40, 60, and 80 min) to investigate the energy damage characteristics and the constitutive model of ground magnesium slag-based cemented backfill in depth. The effects of curing age and magnesium slag grinding time on the energy evolution and distribution characteristics, as well as energy indexes at characteristic points of magnesium slag-based backfills, were examined. From the perspective of energy dissipation, damage variables and modified damage constitutive models were proposed to address the shortcomings of existing damage constitutive studies. The results of the study show that extending the curing age can effectively increase the energy storage limit of backfill and exhibit higher linear elastic deformation capacity. The elastic energy ratio curves of the backfill show an upward and then a downward trend, while the dissipated energy ratio curves show the opposite trend. The relationship between the total energy at the peak stress and the curing age and magnesium slag grinding time can be characterized by linear and quadratic polynomial functions, respectively. The pre-peak energy consumption, post-peak energy consumption, total energy consumption, and energy storage limit of magnesium slag-based backfill all show a linear increase with increasing curing age. The modified energy damage constitutive of magnesium slag-based backfill considering the compaction stage and residual strength shows higher consistency with the test constitutive, which can more realistically reflect the deformation process of the backfill. These results can provide a theoretical basis for investigating the stability of magnesium slag-based backfills in mine filling applications.

Experimental Study on Acoustic Emission Features and Energy Dissipation Properties during Rock Shear-Slip Process.

The features of rock shear-slip fracturing are closely related to the stability of rock mass engineering. Granite, white sandstone, red sandstone, and yellow sandstone specimens were selected in this study. The loading phase of "shear failure > slow slip > fast slip" was set up to explore the correlation between fracture type, acoustic emission (AE) features, and energy dissipation during the rock fracturing process. The results show that there is a strong correlation between fracture type, energy dissipation, and AE features. The energy dissipation ratio of tension-shear (T-S) composite, shear, and tensile types is 10:100:1. The fracture types in the shear failure phase are mainly tensile and TS composite types. The differential mechanism of energy dissipation of different rocks during the shear-slip process is revealed from the physical property perspectives of mineral composition, particle size, and diagenetic mode. These results provide a necessary research basis for energy dissipation research in rock failure and offer an important scientific foundation for analyzing the fracture propagation problem in the shear-slip process. They also provide a research basis for further understanding the acoustic emission characteristics and crack type evolution during rock shear and slip processes, which helps to better understand the shear failure mechanism of natural joints and provides a reference for the identification of precursors of shear disasters in geotechnical engineering.

Seismic behavior and resilience assessment of prefabricated beam–column joint with replaceable graded-yielding energy-dissipating connectors

Conventionally assembled monolithic concrete frame structures achieve structural ductility through beam-end failure, which results in structures that are difficult to repair after an earthquake. To improve the seismic and resilience performance, a prefabricated concrete beam–column joint with replaceable graded-yielding energy-dissipating connectors (RGECs) is introduced. The connectors assembled on the upper and lower sides of the beam end dissipate energy and transfer the beam-end load with the steel hinge device. By adjusting the design bearing-capacity coefficient of RGECs to precast beams, the plasticity and damage of the structure can be centered on the core energy-dissipation bending–shear components (BSCs) and buckling segment (BS) of the RGEC, and the structural function can be quickly recovered by replacing only the damaged RGECs after a seismic disaster. Moreover, compared to the conventional joints, the joint with RGEC can achieve target seismic-performance goals at different seismic-risk levels by designing BSCs and BS with graded yielding. Low-cyclic-loading tests were performed on seven full-scale beam–column joint specimens to investigate the effects of different core energy-dissipating member thicknesses, beam reinforcement ratios and loading protocols on the seismic behavior of the proposed joint. Subsequently, the damaged RGECs were replaced, and the structural-function resilience performance was evaluated in terms of the function-recovery efficiency and quality, indicated by the hysteresis response, strain development, and component energy dissipation. The experimental results proved that the beam–column joint exhibited excellent seismic performance and could realize graded-yielding energy dissipation. The damage to the specimens was concentrated in the RGECs, the key members (beams and columns) were in an elastic state, and the energy dissipation ratio of the RGEC was more than 97 %. This enables the rapid recovery of function after earthquakes. After replacing the RGEC, the hysteresis response, strain development, and component energy dissipation of the specimens were consistent with those of the initial specimens. Compared with the original specimen, the difference in each seismic index of the replaced specimen was less than 10 %. Additionally, the structural function recovered quickly, and the resilient performance was good.

Energy evolution and damage model of sandstone under seepage-creep-disturbance loading

The geological environment of deep coal seam is complex, and the failure mechanism of coal seam under the action of seepage pressure and disturbance stress is unclear, which restricts the development of deep ground engineering. In this study, triaxial compression test of sandstone under seepage-creep-disturbance loading (SCD) was carried out to analyze the characteristics of disturbance deformation, creep rate and permeability. The focus was on the energy evolution law of sandstone under SCD, and the damage creep model was constructed based on the energy proportion. The results show that the creep increment of sandstone under disturbed load was significantly higher than that under undisturbed load, and the stress level can promote the expansion and development of microcracks, in which the creep increment under high stress level showed a jump increase. The total energy and elastic energy of sandstone showed a step change with time. The damage factor under disturbance load was defined in the form of energy dissipation ratio, and the corresponding coupling damage factor was determined by considering the seepage factor and creep factor, which can reflect the coupled damage deformation of sandstone under SCD. Based on fractional order theory, a nonlinear damage creep model describing sandstone deformation under SCD was established by connecting the acceleration element in series with the Nishihara model and introducing the coupling damage factor. This study can provide research ideas for water inrush of coal seam rock mass.

Low-temperature performance and micro-structure of warm mix recycled composite aged asphalt

Given the cold winters in Inner Mongolia, the low-temperature performance of asphalt pavement is one of the key factors affecting the service life of roads. This study focuses on commonly used SBS modified asphalt and investigates the coupling effect of adverse factors such as solar radiation, high temperature, and precipitation on road surface asphalt. The objective is offer insights for improving the applicability and service life of warm mix recycled asphalt in cold regions. By using indoor simulation aging equipment, asphalt subjected to hot oxygen aging, composite water aging, and composite ultraviolet aging was prepared to investigate the low-temperature performance of warm mix recycled asphalt. Additionally, to explore the synergistic effect of new asphalt, regenerant, and warm mix agent on the regeneration of aged asphalt, this study analyzes the low-temperature performance and microstructure changes of recycled asphalt through bending beam rheometer (BBR) test, atomic force microscopy (AFM) test, and infrared spectroscopy (FTIR) test. The results show that as the degree of aging increases, the low-temperature crack resistance performance of asphalt deteriorates. Additionally, after the regeneration of aged asphalt, the damping ratio and dissipation energy ratio of warm mix recycled asphalt slightly enhances compared to hot mix recycled asphalt. Furthermore, the incorporation of a warm mix agent enhances the asphalt’s fluidity, viscosity, surface toughness, and further its low-temperature performance. The AFM test results show that the synergistic effect of warm mix agents and regeneration effectively restores the microstructure and surface roughness of asphalt. Moreover, the warm mix agent improves the dispersion uniformity of the SBS modifier in asphalt, helping prevent the agglomeration of asphalt slurry. Qualitative and quantitative analysis of asphalt through FTIR test demonstrates that the mechanisms of warm mix agents and regeneration on new and aged asphalt are a physical process. New asphalt and regeneration supplement the internal lightweight components of aged asphalt, enabling the restoration of most asphalt without affecting the structure of SBS modified asphalt. This project provides a theoretical basis for the engineering applicability of high content warm mix recycled asphalt (composed of 50 % aged asphalt) in large temperature range areas.

On the effect of strain rate during the cyclic compressive loading of liquid crystal elastomers and their 3D printed lattices

Nematic liquid crystal elastomers (LCEs) are a unique class of network polymers with the potential for enhanced mechanical energy absorption and dissipation capacity over conventional network polymers because they exhibit both conventional viscoelastic behavior and soft-elastic behavior (nematic director changes under shear loading). This additional inelastic mechanism makes them appealing as candidate damping materials in a variety of applications from vibration to impact. The lattice structures made from the LCEs provide further mechanical energy absorption and dissipation capacity associated with packing out the porosity under compressive loading.Understanding the extent of mechanical energy absorption, which is the work per unit mass (or volume) absorbed during loading, versus dissipation, which is the work per unit mass (or volume) dissipated during a loading cycle, requires measurement of both loading and unloading response. In this study, a bench-top linear actuator was employed to characterize the loading-unloading compressive response of polydomain and monodomain LCE polymers and polydomain LCE lattice structures with two different porosities (nominally, 62% and 85%) at both low and intermediate strain rates at room temperature. As a reference material, a bisphenol-A (BPA) polymer with a similar glass transition temperature (9 °C) as the nematic LCE (4 °C) was also characterized at the same conditions for comparing to the LCE polymers. Based on the loading-unloading stress-strain curves, the energy absorption and dissipation for each material at different strain rates (0.001, 0.1, 1, 10 and 90 s-1) were calculated with considerations of maximum stress and material mass/density. The strain-rate effect on the mechanical response and energy absorption and dissipation behaviors was determined. The energy dissipation ratio was also calculated from the resultant loading and unloading stress-strain curves. All five materials showed significant but different strain rate effects on energy dissipation ratio. The solid LCE and BPA materials showed greater energy dissipation capabilities at both low (0.001 s−1) and high (above 1 s−1) strain rates, but not at the strain rates in between. The polydomain LCE lattice structure showed superior energy dissipation performance compared with the solid polymers especially at high strain rates.

Cyclic performance of precast hollow core slab to beam connections using innovative assembling technique

This study emphasizes the performance of novel assembling technique using anchored continuity bars as a connection detail between precast hollow core slab and beam, aiming to achieve faster assembly and increased efficiency. The study further conducts a detailed analysis of core rebar impact on the hollow core slab to beam connection, examining both the assembly technique and core rebar influence. Effectiveness assessment of newly introduced anchored continuity bars and core rebars utilized five full scale half span prototypes under reverse cyclic loading. Findings indicate that connections incorporating anchored continuity and core rebar exhibit high strength, less stiffness deterioration, high ductility, and substantial energy dissipation, thereby meeting seismic load requirements. All connections met ACI 374.1–05 criteria, demonstrating satisfactory performance in seismic tests concerning relative energy dissipation ratio and stiffness ratio criteria. Notably, the continuity bar anchored to beam reinforcement-core reinforcement anchored to beam with ties connection surpasses the continuity bar anchored to beam reinforcement connection, demonstrates a superior average peak load carrying capacity of 149.8 % and cumulative energy dissipation of 288.78 %. The study concluded that the innovative assembly using anchored continuity bar with the inclusion of core rebar in the voids contributes to the improvement of connection performance under positive drift moment capacity and partly enhances negative drift moment capacity, thereby enhancing the overall stability of floor units in the event of seat loss.

Study on the Meso-Failure Mechanism of Granite under Real-Time High Temperature by Numerical Simulation

In the development of geothermal resources in hot dry rocks, deep underground rock masses are typically subjected to real-time high-temperature environments. High temperatures alter the physical and mechanical properties of the rocks, directly affecting the safe and efficient utilization of hot dry rock resources. Therefore, a grain-based model (GBM) of particle flow code (PFC) was constructed based on uniaxial compression tests, and the model was verified according to macroscopic mechanical parameters and damage modes, in order to carry out the simulation study of the uniaxial compression of granite and explore the meso-failure mechanism of granite under real-time high temperature. The relationships between stress–strain curves and crack derivation, the evolution of microcracks, and the characteristics of acoustic emission activity and energy changes at different temperatures were investigated in conjunction with the results of laboratory tests. The results show that crack development, acoustic emission activity, and energy evolution during uniaxial compression include four main stages: initial compression, elasticity, plastic strengthening, and post-peak damage. The failure of granite is primarily controlled by mica and feldspar. During loading, intergranular tensile cracks first emerge within the granite, followed by intragranular tensile cracks, with shear cracks appearing last. As the temperature increases, the total number of microcracks continuously rises, the frequency of acoustic emission events increases, and both dissipated energy and boundary energy gradually decrease, showing an upward trend in the energy dissipation ratio, indicating an increase in thermal damage due to high temperatures. At 400 °C, the rate of microcrack formation increases significantly, with intergranular and intragranular cracks starting to coalesce into macroscopic cracks that extend outward. In the post-peak stage, the phenomenon of multiple peaks in acoustic emission events begins to appear. At 600 °C, the rate of microcrack formation reaches its maximum, with cracks extending throughout the sample to form a network of fractures, resulting in the granite exhibiting ductile failure characteristics.

Dynamic response and constitutive model of damaged sandstone after triaxial impact

In deep rock engineering, dynamic hazards such as blasting and earthquakes pose serious threats to the safety of underground rock structures, including mining and construction activities. To explore the dynamic mechanical properties and damage mechanisms of rocks under realistic ground stress conditions, this study utilized dynamic triaxial compression tests under hydrostatic pressure. These tests employed a modified split Hopkinson pressure bar (SHPB) technique at various strain rates. Wave velocities of the specimens were measured before and after the tests to calculate the damage factor based on the P-wave velocity. Additionally, dynamic uniaxial compression tests on the damaged sandstone specimens indicated a significant reduction in dynamic strength as the damage impact air pressure increased. There was also a notable correlation between the dissipated energy ratio and the level of rock damage, with more severe damage resulting in a smaller dissipated energy ratio. Macroscopic examination through sieve grain size results confirmed the formation of more cracks under high impact air pressure, while microscopic analysis using scanning electron microscopy (SEM) images uncovered the damage mechanisms within the rock post-impact. Ultimately, this study developed an improved ZWT model to effectively verify the dynamic response of the damaged sandstone.

Targeted Energy Transfer Evaluation for Nonlinear Vibrations of Elastic Medium-Finite Length Beam System Using Nonlinear Energy Sink Theory

The elastic medium can usually reduce the vibration of supporting structure, and the impact of the interaction on the vibration characteristics of the structure is similar to the characteristic of nonlinear energy sink. At present, the dynamic research of beam on elastic foundation considering soil motion has been paid more and more attention. According to the modified Winkler model, the finite-depth elastic medium can be considered to the nonlinear energy sink mass, and the vibration energy dissipation capacity and parameter optimization of the elastic medium supporting finite-length beam under half sine pulse are studied. The Galerkin truncation is applied to the discretization of the governing equations. The numerical solution of the beam coupling system with simple support on the elastic medium is obtained by applying the fourth-order Runge–Kutta method. Based on this, the input energy ratio of the elastic medium dissipation is investigated. Furthermore, through the analysis and optimization of targeted energy transfer and dissipation, the dissipation effect of the finite range elastic medium on the vibration energy of its supporting beam is revealed, and the optimal parameter range of the elastic medium is proved. The results show that after adjusting the elastic medium parameters by technical means, the nonlinear energy sink can absorb most of the vibration energy of the beam quickly and effectively, and the optimal energy dissipation ratio can reach 95.16[Formula: see text]. The quantitative evaluation of the energy dissipation in elastic medium within soil–structure interaction effect is realized.

Development of 3D printed tissue-mimicking materials: Combining fiber reinforcement and fluid content for improved surgical rehearsal

The prevalence of medical errors during surgical procedures has led to a higher emphasis on improving surgical outcomes, by improving surgical planning and training. Anatomical models have become valuable tools for pre-operative planning and current 3D printed models strive to better match real soft biological tissues. This study aimed to develop novel 3D printed material composites with controllable mechanical properties that mimic soft tissue. Concepts of microstructuring, fiber reinforcement and fluid infill in extrusion-based 3D printing are combined to design tunable materials towards target tissues of porcine muscle and liver. Material characterization was performed in triangular wave cyclic experiments under uniaxial tension with increasing displacements. Hereby, initial EI and final EII elastic moduli were evaluated. Further, the viscous response was characterized by the dissipated energy ratio UD and suture retention strength (SRS) was determined by single tensile pull-out tests Elastic moduli of printed materials were successfully tuned to 510 ± 10 kPa, closely resembling porcine muscle with 580 ± 150 kPa. The dissipated energy ratio UD of the silicone was increased from 0.09 ± 0.01 to 0.46 ± 0.17 by addition of gyroid infill and viscous fluid. Suture retention strength (SRS) for porcine liver tissue was 1.64 ± 0.42 N, while that of 3D printed silicone showed a mean SRS of 5.1 ± 0.6 N. Although the exact properties of porcine muscle and liver tissue require finer tuning, this study established techniques for refinement of 3D printed tissue-mimicking materials, ultimately enabling more accurate models for surgical rehearsal.

Exploring the mechanism of amylose/amylopectin improving formation of yeast-soy protein high-moisture extrudates based on small and large amplitude oscillatory shear rheology

Yeast protein (YP) has high production efficiency and comprehensive nutritional value compared to soy protein isolate (SPI). However, relatively higher proportion of YP replaces SPI seriously affect the structure of extrudates in the production of meat analogues. This study investigated starch addition (amylose/amylopectin) on the structure of YP-SPI extrudates with higher YP proportion and formation mechanism by using closed cavity rheometer simulated the high-moisture extrusion process (mixing, melting, cooling, and extrudates). The proportions of YP:SPI:amylose:amylopectin were set as 5:5:0:0, 5:4:1:0, 5:4:0:1, and 5:4:0.5:0.5. Starch addition could improve the structure formation of extrudes, but the improvement effect varied depending on the type of starch. Compared to amylose, incorporating amylopectin significantly enhanced the fibrous degree of extrudates and improved their tensile resistance. Furthermore, small amplitude oscillatory shear (SAOS) was used to establish texture map. In the mixing and melting zones, amylose decreased the miscibility of protein and starch phase, while amylopectin had positive effect on the integrity and uniformity of protein network. Amylopectin could transform the extrudates into a “mushy” state, contributing to reconstruct protein network. Large amplitude oscillatory shear (LAOS) demonstrated amylopectin had higher energy dissipation ratio in the cooling zone, indicating the uniform “phase separation” facilitated the formation of fiber structure of extrudates. This study provides technical reference for the preparation of high-moisture extrudates using YP as a substitute for SPI based on starch type addition.

Manipulating the Properties of Polymer Vitrimer Nanocomposites by Designing Dual Dynamic Covalent Bonds.

Polymer vitrimer is a novel material that contains dynamic covalent bonds (DCBs) allowing it to combine the desirable characteristics of both thermoplastics and thermosets. Similar to the traditional polymer nanocomposites, introducing nanoparticles into polymer vitrimer is also an effective strategy to further enhance its properties. However, a comprehensive understanding of matrix and interfacial bond exchange reactions (BERs) to tailor the properties of polymer vitrimer nanocomposites (PVNs) is still lacking. Herein, we utilized coarse-grained molecular dynamics simulations to investigate model PVNs in which there are two different kinds of DCBs in the vitrimer matrix and at the interface. Our results show that the normalized bond autocorrelation function (Csw) confirms the independence of BERs in the vitrimer matrix and in the interface. By varying the bond swap energy barrier () in the matrix or in the interface , or in both , a maximum mechanical property is observed at the moderate value of , , or. Meanwhile, the effect of on the stress relaxation and the bond orientation as a function of the time under a fixed strain is well probed, which both decay more slowly at greater . We simulated the tension-recovery curve to examine the effect of on the hysteresis loss and permanent deformation of PVNs, finding an optimal value to achieve its minimum energy dissipation and maximum recovery ratio. Lastly, we investigated the efficiency of self-healing by building and removing walls from the system. Interestingly, a maximum self-healing efficiency of the stress-strain behavior is observed at moderate . Overall, this study provides valuable insights into the relationship between the structure and properties of PVNs, offering implications for the manipulation of their mechanical properties and enhancement of their self-healing capabilities.

Analysis of Pore Characterization and Energy Evolution of Granite by Microwave Radiation

To study the dynamic response of granite to different levels of microwave power, an intelligent microwave rock-breaking instrument is used to irradiate different power from three directions. The servo universal testing machine is used to carry out a uniaxial compression test on the granite after microwave damage to analyze the strength damage characteristics and the degree of pore damage. Pore fractal characteristics are analyzed based on nuclear magnetic resonance to establish the microwave damage degradation model. In parallel, the energy evolution process of granite under the influence of various power levels is analyzed using the theory of energy dissipation. Simultaneously, based on the energy dissipation theory, we analyze the energy evolution process of granite under the action of different powers. The results show that with higher microwave power, the peak strength and modulus of elasticity show a linear decreasing law. The degree of fragmentation is more obvious, showing the damage characteristics with two big ends and little in the middle. The higher the power, the greater the porosity and the more sensitive the micropore becomes to microwaves. Additionally, the damage degradation model established to evaluate the microwave damage of the rock showed that it was feasible. The higher the power, the lower the total energy, elastic energy, and dissipation energy, and the granite is gradually transformed from elastic deformation to plastic deformation. The elastic energy ratio decreases, the dissipation energy ratio increases, and the degree of damage becomes more and more serious. This study provides theoretical support for exploring the mechanical behavior and mechanism of microwave-assisted rock breaking and is of great practical significance.

Optimal energy dissipation ratio of base-rocking walls

Base-rocking walls (BRWs) were excellent in maintaining enhanced post-earthquake serviceability and decreasing repair costs and downtime. However, little research has been aimed at finding the optimal range of energy dissipation ratio for designing BRWs. In this study, an approach was developed first for designing BRWs to obtain an intended level of energy dissipation capacity. Using the proposed approach, fifteen BRWs with different heights (i.e., 16, 25.6, and 38.4 m) and energy dissipation ratios (i.e., 0, 0.25, 0.50, 0.75, and 1.00) were designed and modeled using experimentally validated numerical models. Conducting nonlinear time history analyses using far-field (FF), near-field no-pulse (NFnP), and pulse-like (NFP) ground motions, the walls’ response features (RFs), including residual and transient lateral drifts, story acceleration, energy dissipation capacity, post-tensioning (PT) tendons strain, and structural demand were estimated and compared to the existing criteria. Proposing a desirability index (DI), the extent of criteria exceedance for the walls RFs was investigated to find the optimal range of energy dissipation ratio. The results showed that the walls designed by the developed approach could achieve the pre-assumed energy dissipation capacity. Increasing the energy dissipation ratio increases the lateral residual drift while decreasing the transient lateral drift, PT tendon strain, and wall demand. Increasing the wall height increases dissipated energy, exacerbating the adverse effects of higher modes while decreasing PT tendon strain. The obtained residual and transient drifts and PT tendon strain for NFP records are higher than those for FF and NFnP records. Moreover, the peak moment occurred at the lower wall height for NFP records. The adverse effects of higher modes are more evident in FF records. In general, for designing BRWs, the optimal energy dissipation ratio range was 0.50–0.75.

Dissipated Energy and Pore Pressure Generation Patterns in Sands and Non-Plastic Silts Subjected to Cyclic Loadings

The factors that influence dissipated energy and pore pressure generation patterns with respect to the cycle ratio and dissipated energy ratio were analyzed using the results of cyclic triaxial and cyclic direct simple shear tests. These analyses revealed several interesting differences in pore pressure generation patterns when related to cycle ratio than to dissipated energy ratio. Soils with different pore pressure generation patterns when plotted against the cycle ratio were found to have nearly identical pore pressure generation patterns when plotted against the dissipated energy ratio. The differences exist as the result of the fundamental differences between cycle ratio and dissipated energy ratio. The fundamental difference is that pore pressure generation is directly linked to the process of energy dissipation; it is not inherently linked to cycles of loading. Therefore, to achieve an understanding of the pore pressure response of a soil that is independent of the specifics of the applied loading, one needs to evaluate it in terms of energy dissipation, not in terms of cycles of loading, especially irregular loadings.

Vision-oriented machine learning-assisted seismic energy dissipation estimation for damaged RC beam-column connections

After a seismic event, damage quantification is necessary for safety evaluation, collapse proximity judgment, and measurement of the residual seismic capacity of the joints. Machine learning-based predictive models are developed in this paper aimed at the non-destructive and non-contact estimation of energy dissipation ratio for seismically damaged beam-column joints through surface crack texture complexity indices. For this purpose, the authors collected an experimental dataset comprising 934 images of cracked and/or crushed reinforced concrete-framed joints from 254 specimens under cyclic loading. The associated energy dissipation ratios are then extracted from the lateral load-displacement hysteresis curves for each image by the authors, along with the image-derived fractal indices. Machine learning models with six algorithms, including Linear Regression, Multi-Layer Perceptron, Decision Tree, Random Forest, Gradient Boost, and CatBoost, are trained by 80% of images as a training dataset and validated through the remaining 20% of images in two scenarios. The first scenario develops models by component geometric dimensions and generalized fractal indices calculated for the beams, columns, and joints of seismically damaged connections, while the second scenario adds structural parameters to visual indices to estimate the energy dissipation ratio as the target parameter. Performance evaluation of trained models in the mentioned scenarios via common correlation and accuracy measures, along with the k-fold cross-validation method, indicated that CatBoost-based ML models in both scenarios provide optimal results with R2 = 0.89, RMSE = 0.10 for scenario I and R2 = 0.92, RMSE = 0.09 for scenario II using testing dataset. The first scenario based on the CatBoost algorithm with the R2 variation range of 0.07 and RMSE variation range of 0.03 across the test folds provides a sufficient performance in terms of generalizability and accuracy for estimating the energy dissipation ratio through lower number of input variables.