External Load Research Articles

Dynamics of the Euler — Bernoully beam with distributed hysteresis properties

In this paper, we present a new mathematical approach to the analysis of a beam with distributed hysteresis properties. These hysteresis characteristics are described by two methods: phenomenological (Bouc — Wen model) and constructive (Prandtl — Ishlinskii model). The equations for beam are developed using the well-known Hamilton method. We investigate the dynamic response of a hysteresis beam under various external loads, including impulse, periodic and seismic loads. The results of numerical simulations show that the hysteresis beam exhibits differently to external influences as compared to the classical Euler-Bernoulli beam. In particular, under the same external loads, the vibration amplitude and energy characteristics of the hysteresis beam are lower than those of the classical one. These findings can be useful for buildings developers in the design of external load resistant buildings and structures

Research the lubrication characteristics on the modified main thrust roller of the slewing bearings

The load capacity and lubrication performance of the slewing bearing are fairly sensitive to edge effects at both ends of the main thrust rollers. Therefore, quantitative investigations of the edge effect at both ends of slewing bearing is practically important. In this study, an elastic fluid lubrication model of the slewing bearing that considered the external load and internal structural parameters is established. A modification function of rollers is included in a finite long-line contact elastic fluid lubrication model to perform the dynamic analysis. The simulated oil film’s thickness and pressure distributions are compared under different working conditions. And the edge effect is eliminated by modifying the rollers’ construction. The results indicate that under the large eccentric load, the speed of the slewing bearing must be decreased to ensure elastic fluid lubrication performance. A genetic algorithm that used to discover the optimal modification length shows the best busbar of the main thrust roller is 12 μm, which could decrease the vibration amplitude of the unmodified roller by 8.13%. This result gives a significant way for slewing bearing’s structural design.

Simulating Pelvis Kinematics from Belt and Seat Loading in Frontal Car Crash Scenarios: Important Boundary Conditions that Influence the Outcome.

The risk of submarining during automotive crashes, defined by the lap belt sliding off the pelvis to load the abdomen, is predicted to increase in future autonomous vehicles as greater variation in seating position is enabled. Biofidelic tools are required to efficiently design and evaluate new and/or improved safety systems. This study aims to evaluate the pelvis response sensitivity to variations in boundary conditions that directly influence the pelvis loads, deemed important for the submarining outcome, to facilitate a more precise comparison between finite element human body models (FE-HBMs) and post-mortem human subjects (PMHSs). A parameter study, using a one-variable-at-a-time analysis (low/high) of belt friction, seat friction, seat stiffness, and (on/off) for added belt bending stiffness, was performed using a state-of-the-art FE-HBM in four different test scenarios; one stationary, two sleds with upright occupant posture, and one sled with reclined occupant posture. In the stationary scenario, both belt friction and belt bending stiffness influenced the belt folding behavior, which consequently affected the belt-to-pelvis angle at submarining. In the sled scenarios, only seat friction was found to influence the pelvis kinematics and submarining outcome, with the most biofidelic response resulting from both the low (0.2) and high (0.5) friction coefficient depending on the scenario. To reduce uncertainty in boundary conditions affecting the external pelvis loads and increase confidence in FE-HBM to PMHS comparisons, it is recommended that future experiments evaluate the PMHS to seat friction coefficient and that new belt modeling methods that accurately capture belt folding when interacting with soft tissues are developed.

The effect of external force on the crack propagation of aluminum nanoplate using molecular dynamics approach: Insights into the fracture mechanisms of metallic nanomaterials under external loading condition

It is crucial to comprehend how external forces (EFs) affect crack propagation (CP) in aluminum (Al) nanoplates to develop and create nanomaterials with enhanced mechanical characteristics. The creation of novel materials for a variety of uses, such as the aerospace, electronics, and energy sectors, may benefit from this expertise. Additionally, insights into the fracture mechanisms of nanomaterials can aid in designing more reliable and durable structures at the nanoscale. This study utilized computer models to investigate the effect of EFs on fractures in Al nanoplates. The results suggest that an EF can significantly alter CP within nanoplates. The findings provide insights into the fracture mechanisms of metallic nanomaterials under external loading conditions. Simulation results in current research showed the physical stability of modeled Al nanoplates at T=300 K as the initial temperature. Numerically, the total energy (TE) of pristine nanoplate converged to −34762.953 eV after thermodynamic equilibrium detection inside the computational box. Furthermore, the simulation results show that EF caused the crack growth procedure intensity to increase. In the present study, the crack length value increased to 33.902 Å between our modeled samples. This result led to the conclusion that in real-world applications, it is important to consider the effect of EFs on the development of cracks within Al nanoplates.

Micro–Macro Coupling Study on the Mechanical Properties of Continuous Fiber-Reinforced Composites

As a key and weak point of continuous fiber-reinforced composites (CFRCs), the interface between the fiber and the matrix is vulnerable to failure under external loads, with its performance directly affecting the overall properties of CFRCs. Hence, a micro–macro coupling method that considered the microscopic properties of the interface was utilized to analyze and predict the mechanical properties of CFRCs more accurately. The microscopic mechanical parameters of the fiber–matrix interface, which were obtained using molecular dynamics, were transferred to the representative volume element (RVE). The stiffness matrix of the CFRC, required for the macroscopic finite element model, was then calculated using a unified periodic homogenization method based on the RVE and assigned to the finite element model for a macroscopic simulation. Nylon/continuous carbon fiber specimens were fabricated through additive manufacturing, with the tensile and bending strengths of the specimens obtained through tensile and three-point bending tests. The tensile strength of the experimental specimen was 200.1 MPa, while the result of the simulation containing the interface was 205.5 MPa, indicating a difference of less than 5% between the two. In contrast, the result of the simulation without an interface was 317.7 MPa, representing a high error of 58.7% compared with the experimental results. Moreover, the bending strength, Young’s modulus, and flexural modulus results with and without an interface showed the same trend as that for the tensile strength. This illustrates the effectiveness of the proposed micro–macro coupling method for analyzing and predicting the mechanical properties of CFRCs.

Development of a microfluidic system with a bearing micropump for applying fluid shear force in an intervertebral disc degeneration model involving mechanical stimulation

Background: The intervertebral disc (IVD) functions as a shock absorber with viscoelastic tissues, including the gelatinous nucleus pulposus and the collagenous annulus fibrosus (AF). External mechanical loading influences IVD homeostasis but can cause damage and inflammatory reactions, contributing to disc degeneration. There is a lack of in vitro platforms for modeling IVD disease with mechanical stimulation.Methods: This study aimed to create a mechanical stimulation-based model by subjecting AF cells to shear stress using a micropump system. A micropump platform was used to measure pulsation, flow rate, and shear stress. AF cells were exposed to fluid shear stress of 0.5 and 1 dyne/cm², and morphological changes, cytotoxicity, and cell viability were analyzed through a live/dead assay. Perimeter, area, diameter, and elongation were assessed using live cell imaging and imaging analysis software.Results: The micropump platform exhibited optimal rotor characteristics for uniform pulsation and shear stress. Fluid shear stress at 0.5 dyne/cm² showed no significant difference from the control group, while 1 dyne/cm² reduced cell adhesion and survival. Comparing the 0.5 dyne/cm² shear stress group and interleukin-1β group to the control, significant decreases in perimeter, area, and diameter were observed.Conclusion: The study successfully developed a micro-peristaltic pump platform for applying fluid shear stress to cells, identifying an optimal rotor for uniform stress application. The platform effectively modeled IVD disease, revealing reduced cell adhesion and survival under specific shear stress conditions. This platform has potential promise for discovering biomarkers and exploring cellular responsiveness to external stimuli.

A Comparison of Match External Load Demands Across Women's Collegiate Field Sports.

Kuhlman, NM, Jagim, AR, Jones, MT, Feit, MK, and Fields, JB. A comparison of match external load demands across women's collegiate field sports. J Strength Cond Res XX(X): 000-000, 2024-Historically, soccer (SOC), lacrosse (LAX), and field hockey (FH) have been grouped together as "field sports" due to their intermittent nature of match play and similar physiological demands. However, questions have emerged regarding potential variations in demands between sports. The purpose of this study was to compare external match workloads between collegiate women's SOC, LAX, and FH, and examine within-sport positional differences. Athletes (SOC: n = 15; LAX: n = 15; FH: n = 14) wore a global positioning system device during all matches throughout a competitive season. External load metrics included in the analysis were total distance (TD), sprint distance (SD), accelerations (>3 m·s-2), sprint efforts (SE), player load (PL), PL per minute (PL/min), top speed (m·s-1), and distances covered in select speed zones. Soccer performed higher external load volumes (TD, PL) (p ≤ 0.025) but incurred lower intensities (SD, SE, accelerations) (p < 0.001) compared with LAX and FH. Within-sport positional differences were apparent in SOC (p < 0.001-0.018), LAX (p < 0.001-0.045), and FH (p < 0.001-0.004). However, FH exhibited more positional variance in external load metrics compared with SOC or LAX. Field hockey midfielders covered greater volumes (TD, PL) compared with attackers and defenders (p < 0.001), while attackers sustained greater intensities (SD, SE, top speed) compared with midfielders and defenders (p < 0.004). Results indicate that there are significant differences in external workload parameters between sports and across positions. Practitioners should tailor sport-specific and position-specific programs to match demands, and future research should explore the proposed categorizations of LAX as a "fast collision invasion sport," FH as a "fast contact invasion sport," and SOC as a "slow contact invasion sport."

Neuromuscular Performance and the Intensity of External Training Load During the Preseason in National Collegiate Athletic Association Division I Men's Collegiate Basketball Players.

Curtis, M, Kupperman, N, Westbrook, J, Weltman, AL, Hart, J, and Hertel, J. Neuromuscular performance and the intensity of external training load during the preseason in National Collegiate Athletic Association Division I men's collegiate basketball players. J Strength Cond Res XX(X): 000-000, 2024-The aim of the study was to determine whether acute changes in neuromuscular performance can be detected through countermovement jumps (CMJs) conducted pre- and postpractice sessions in conditions of high or low intensity measured by microsensors technology. Using an observational repeated measures design, data were collected from 10 male collegiate basketball players. Countermovement jump data were collected before and after practice exposures over 4 weeks of preseason. Select CMJ kinetics were compared in conditions of high and low training load intensity to detect neuromuscular performance changes in displacement of the center of mass and kinetics. Kinetic measures were categorized as output, underpinning, and strategy-related variables. We investigated "output" defined as displacement (jump height [JH]), "underpinning" defined as force-related (mean eccentric force, mean concentric force, force at zero velocity), and "strategy" defined as time-related (countermovement depth [CMD], eccentric duration (EccDur), concentric duration [ConcDur]) variables. There were significant condition × time interactions in CMJ variables namely eccentric mean force (EccForce), force at zero velocity (Force@0), CMDepth, EccDur, and ConcDur. In conditions of high intensity, players had significant, but small decreases in EccForce and Force@0, with small increases in CMD, EccDur, and ConDur, respectively. However, there were no significant decreases in JH. High-intensity practice exposures did not impact neuromuscular performance specific to "output," suggesting that collegiate basketball athletes can maintain JH despite alterations in "underpinning" and "strategy-related" variables. This could have relevance in understanding how fatigue associated with higher-intensity training exposures may potentially alter jump strategy and force production capacities due to external load intensity in collegiate basketball athletes.

Layer-by-layer assembling boron nitride/polyethyleneimine/MXene hierarchical sandwich structure onto basalt fibers for high-performance epoxy composites

Interfacial adhesion directly affects the mechanical properties of basalt fiber (BF)-reinforced polymer composites. To construct a more superior interphase between BFs and epoxy resin (EP) than a weak interphase of the unmodified BF/EP, we propose a hierarchical sandwich structure consisting of sodium hydroxide–activated boron nitride (BNOH), polyethyleneimine (PEI), and MXene (MX, Ti3C2Tx) through facile layer-by-layer self-assembly. The fabricated BNOH/P/MX sandwich structure (P denoting “PEI”) can synergistically improve the interface adhesion by enhancing the mechanical interlocking and chemical bonding of the composites. When the composites reinforced by BF–BNOH/P/MX subject to the external loading, flexible PEI molecules allow two-dimensional (2D) rigid BNOH and MX nanosheets to slip at the interface by uncurling the molecular chains, dissipating a great amount of energy during the fracture progress. Meanwhile, the hierarchical BNOH/P/MX sandwich structure acts as an excellent interface and possesses multistage gradient modulus and wider thickness, uniformly and efficiently transferring the stress from the EP matrix to BFs. The interfacial shear strength, impact strength, and fracture toughness of BF–BNOH/P/MX-reinforced EP composite are substantially improved by 45.9 %, 60.6 %, and 148.9 %, respectively, compared with bare BF–based composites. This study can provide valuable references and inspirations for designing and constructing high-quality interfaces for high-strength and high-toughness BF structural materials, taking advantage of 2D materials.

Static expansion fracturing mechanism for enhancing gas permeability in low permeability coal seams

Extraction of gas from low-permeability thick coal seams poses challenges globally, attributed to low extraction efficiency, limited enrichment content, and extraction complexities. Investigating static fracturing in low-permeability thick coal seams holds substantial engineering significance and practical utility. This research delves into the current conditions in the Western region, characterized by low gas permeability and challenging extraction in thick coal seams. Through the utilization of FLAC3D and COMSOL, simulation schemes are devised to analyze the influence of borehole parameters on fracture efficacy, elucidating the mechanisms by which external loads and internal gas pressure impact coal seam permeability. Field monitoring tests are employed to evaluate and model gas extraction enhancement via borehole positioning. The results suggest that the application of a static fracturing agent inducing 40 MPa expansion stress, along with a 75 mm borehole diameter and 0.5 m spacing, effectively fractures low-permeability thick coal seams. The spacing between extraction and fracturing holes adversely affects gas extraction efficiency due to the limited range of static fracturing. Field experiments demonstrate that static fracturing significantly improves gas extraction from low-permeability thick coal seams, resulting in a twofold increase in average gas extraction purity post-fracturing. This study establishes a robust theoretical foundation for optimizing gas extraction and mining activities in challenging low-permeability thick coal seam environments.

A flexural-beam-type wide-frequency piezoelectric energy harvester for vertical shaft lifting system vibration monitoring

Abstract The coal mine lifting system may experience serious safety accidents due to severe problems with the bucket guides and rolling guide shoes. A piezoelectric energy harvesting (PEH) device for vibration sensor monitoring of shaft lifting system is proposed for the first time to monitor health of shaft lifting system. However, there are differences in the vibration frequencies, the working conditions are complex, leading to issues such as low energy recovery efficiency of the PEH and difficulty in achieving self-powered. To enhance PEH adaptability and reliability, a specifically designed flexural-beam-type wide-frequency piezoelectric energy harvester(FBT-WF-PEH) and a method of achieving real-time vibration monitoring through auxiliary power supply have been proposed. The results indicate when the excited frequency is 17Hz, the highest external output voltage is 11.2V, and under an external load of 17.5kΩ, the maximum output power is 7.168mW, demonstrating a good performance in terms of output power, and energy harvest bandwidth. The captive power supply test verified the PEH can utilize the vibration environment to achieve auxiliary power supply for monitoring systems under working conditions, which is of great significance for conducting research on health monitoring systems for lifting equipment. On the other hand, the new structure proposed in this study matches the operating frequency in the shaft lifting system, and the energy harvest efficiency is higher.

In-depth molecular dynamics analysis of crack evolution in polycrystalline chromium under uniaxial tensile deformation

Because of its excellent wear resistance and high hardness, chromium is widely used in coating materials. Under external load, micro-cracks on the surface of electroplated chromium coating will cause crack propagation and reduce the performance of the material. Therefore, in this study, the crack evolution process of polycrystalline chromium under uniaxial tension was studied using molecular dynamics. The effects of average grain size, strain rate, and crack location on crack propagation behavior were analyzed, which provided a scientific basis for optimizing the performance of chromium materials. The results show that cracks in polycrystalline chromium tend to fracture along grain boundaries and that stacking faults and holes are the main factors for crack propagation. As the grain size decreases, the crack passivation becomes more pronounced and the rate of crack expansion slows down. As the strain rate increases, the crystal structure of polycrystalline chromium changes more sharply, and the ultimate stress increases. At high strain rates, the direction of crack propagation changes. The degree of crack tip passivation is affected by the initial crack location, and the crack tip can be effectively passivated when it is located at the grain boundary, thus hindering crack propagation. The results of these studies reveal the influence of multiple factors on the crack propagation mechanism of polycrystalline chromium and provide theoretical guidance for the reduction of chromium coating damage.

Experimental method for internal deformation measurement of 3D solids with embedded cracks based on 3D printing and digital speckle techniques

Quantification of the internal deformation of fractured solids such as rock masses under external loads, especially the deformation around internal fractures, is crucial for understanding and predicting the failure of fractured solids. However, it is very difficult to achieve the goal using conventional experimental methods. In this study, we proposed a novel internal deformation measurement method based on three-dimensional (3D) printing and digital speckle techniques. The 3D printing technology was applied to fabricate a 3D transparent model with an embedded elliptical crack and to set a speckle pattern on the internal section of the transparent model. The digital image correlation (DIC) method was used to determine the internal deformation field of the 3D fractured model. The measured displacements and strains of the internal sections in the fractured model were compared with the numerical simulation results. The comparison indicates that the proposed experimental method can well determine the deformation inside the 3D model. This built-in speckle method can realize real-time observation of the internal deformation of a 3D solid model in a non-contact and non-destructive manner.

Research on Highly Reliable Self-Powered Vibration Sensors for Geological Drilling

Vibration signals at the bottom of the drill string during geological drilling are crucial for lithological identification and drilling parameter optimization. However, existing downhole vibration sensors suffer from limitations in power supply and reliability. This study proposes a self-powered vibration sensor with high redundancy based on the triboelectric nanogenerator principle, which is capable of measuring both axial and transverse vibrations, thereby reducing the dependence on external power sources. The experimental results show that the sensor can measure axial vibration frequencies ranging from 0 to 11 Hz with an error of less than 4% and transverse vibration frequencies ranging from 0 to 5 Hz with an error of less than 5%. It can operate stably in temperatures from 0 to 180 °C and relative humidities from 0 to 95%. The sensor’s axial vibration measurement features six identical measurement structures, providing high redundancy and effectively enhancing its reliability. Furthermore, the sensor exhibits power generation capabilities. When an external load of 1 MΩ is applied to the axial measurement module and 10 MΩ to the transverse measurement module, the sensor achieves its maximum power output for both axial and transverse measurements, reaching 32.4 × 10−9 W and 2.1 × 10−9 W, respectively. Compared to traditional bottom-of-the-hole vibration sensors, this sensor possesses self-powering capabilities and high reliability, which can improve the operational efficiency and hold significant practical value for future applications.

Microstructure, mechanical properties, and shape memory behavior of laser-directed energy deposited Co–20Fe–18Cr–19Mn high-entropy alloy

Laser additive manufacturing has become a powerful tool in modern production processes, and the additive manufacturing of Cantor-type high-entropy alloys has attracted considerable attention owing to its unique properties. In this study, we successfully utilized a laser-directed energy deposition (L-DED) process to fabricate a Co–20Fe–18Cr–19Mn, wt.% (Co40Fe20Cr20Mn20, at.%) alloy and analyzed its microstructure, room temperature mechanical properties, and shape memory effect. Microstructural analysis revealed a dense microstructure of the alloy. Before heat treatment, the alloy exhibited a microstructure consisting of both columnar and equiaxed dendrites with a hexagonal close-packed structure (HCP). However, post-treatment led to a completely different microstructure owing to recrystallization with a face-centered cubic (FCC) structure. Tensile testing results indicated a subtle anisotropy in the yielding, and after heat treatment, a significant enhancement in ductility was observed. A study of the shape memory effect demonstrated that the as-printed samples exhibited an FCC-HCP dual-phase structure, which transformed into an FCC single-phase structure after heat treatment. The application of external loading induced reformation of the HCP phase, successfully demonstrating the shape memory effect in the alloy, with a maximum recovery strain of 0.79 %.

Superior filaments-based fabric with thermal-mechanical-electrical coupling properties for remote temperature alarm

The safeguarding fabrics featuring good thermal insulation, flame retardancy, and force dissipation simultaneously remain challenging due to the current filaments with limited properties. Herein, a novel and flame-retardant filament (F-filament) is developed by hot-extruding the mixture of shear stiffening gel/thermoplastic polyurethane (SSG/TPU) and microencapsulated ammonium polyphosphate (MHAPP), which is conducive to knitting protective fabrics. The conductive F-filament (cF-filament) is further prepared by incorporating with MXene. The F-filament-based fabrics present better anti-impact properties than commercial fabrics and can dissipate 6.32 kN impacting force to 1.89 kN. The patterned knitted fabric also facilitates heat exchange, reducing the contact temperature of the body surface to approximately 37 °C when exposed to an 80 °C heat source, effectively avoiding thermal damage through its porous structure. Moreover, the F-filament-based fabrics are intact even after 19 s of continuous burning. Notably, the cF-filament is demonstrated for use as a sensor for real-time multimodal monitoring, such as detecting external mechanical loadings and temperature stimuli. The cF-filament sensor can be integrated into the F-filament-based knitted fabrics, which accurately realizes environmental monitoring and explores the best-escaping route through a remote temperature alarm system.

Inversion Method for Material Parameters of Concrete Dams Using Intelligent Algorithm-Based Displacement Separation

Integrating long-term observational data analysis with numerical simulations of dam operations provides an effective approach to dam safety evaluation. However, analytical results are often subject to errors due to challenges in accurately surveying and modeling the foundation, as well as temporal changes in foundation properties. This paper proposes a concrete dam displacement separation model that distinguishes between deformation caused by foundation restraint and that induced by external loads. By combining this model with intelligent optimization techniques and long-term observational data, we can identify the actual mechanical parameters of the dam and conduct structural health assessments. The proposed model accommodates multiple degrees of freedom and is applicable to both two- and three-dimensional dam modeling. Consequently, it is well-suited for parameter identification and health diagnosis of concrete gravity and arch dams with extensive observational data. The efficacy of this diagnostic model has been validated through computational case studies and practical engineering applications.

Development of Laminated Egg-Shaped Tsunami Shelter Structure Made of Steel-Cushioning-Steel

When a tsunami is caused by an earthquake or other event, spherical shelters are developed to protect people from the tsunami. This study proposes a new egg-shaped laminated tsunami shelter with a buffer layer to improve the functionality of traditional spherical shelters. The inner and outer shells of this shelter are made from thin-walled stainless steel, using the integral hydro bulge forming (IHBF) process. The space between these two layers was filled with urethane foam, providing an elastic buffer. This resulted in a laminated egg-shaped structure designed for tsunami protection. To verify the proposed laminated egg-shaped tsunami shelter and its processing method, an egg-shaped shell with an external shape (length 660 mm, width 493 mm) was fabricated using a 1.0 mm thick stainless plate, and a laminated egg-shaped tsunami shelter with a 25 mm thick intermediate layer made of urethane foam was fabricated. The shape accuracy of the processed egg-shaped laminated tsunami shelter structure was measured, and the maximum error between the surface shape of the molded egg-shaped shell and the true egg shape was -4.13 mm, and the relative error to the maximum radius of the egg shape of 246.5 mm was -1.68%. In addition, to assess the buffering effect under external impact loads, acceleration sensors were attached to both the inner and outer layers of the fabricated egg-shaped laminated tsunami shelters. A hammer was used to apply an impact load to the outer layer, and the response acceleration values recorded by the sensors on both layers were compared. It was found that the response acceleration of the inner layer was 15.81% lower than that of the outer layer.

Hydrodynamic exposure – on the quest to deriving quantitative metrics for mariculture sites

This work attempts to define metrics for hydrodynamic exposure, using known oceanographic variables to provide a universal site assessment method for mariculture structures. Understanding environmental conditions driving open-ocean mariculture siting is crucial in establishing consistent ocean governance, minimizing adverse environmental impacts, and facilitating economically sustainable farm operations. To provide a metric of oceanic conditions and associated requirements for structural design and operation of aquaculture systems, six Exposure Indices (EI) are proposed that consider physical energy levels related to hydrodynamic forces at a site. Four of the proposed indices consider only environmental conditions, while the other two also consider the dimensions of the gear that is exposed to the external loads. These indices are: Exposure Velocity (EV), Exposure Velocity at Reference Depth (EVRD), Specific Exposure Energy (SEE), Depth-integrated Energy Flux (DEF), Structure-centered Depth-integrated Energy (SDE), and a Structure-centered Drag-to-Buoyancy Ratio (SDBR). While these indices are derived with a focus on aquaculture structures, they may also have applications for estimating biological stressors and operational challenges. The proposed exposure indices were evaluated for a range of known aquaculture sites around the world. A sensitivity analysis was conducted that quantified the relationship between the exposure indices and storm event return period. At a regional scale, hindcast numerical data for the German Bight combined with calculations of 50-year extreme values were used to calculate and map each proposed index spatially. Resulting maps showed that exposure is not simply a function of distance from shore. The six indices show plausible performance regarding the objective assessment of aquaculture sites. The authors herein present the indices to the aquaculture and ocean engineering communities for discussion, application, and potential adoption of one or more of the proposed indices.

Damage Evolution Mechanism of Railway Wagon Bogie Adapter 1035 Steel and Damage Parameter Calibration Based on Gursone-Tvergaarde-Needleman Model.

As a critical component of a train, the railway wagon bogie adapter has higher quality requirements. During the forging process, external loads can induce voids, cracks, and other defects in the forging, thereby reducing its service life. Hence, studying the damage behavior of the forging material, specifically AISI 1035 steel, becomes crucial. This study involved obtaining stress-strain curves for AISI 1035 steel through uniaxial tensile tests at temperatures of 900 °C, 1000 °C, and 1100 °C, with strain rates of 0.1 s-1, 1 s-1, and 10 s-1. Subsequently, SEM was used to observe samples at various deformation stages. The damage parameters, q1, q2 and q3 in the GTN model "a computational model used to analyze and simulate material damage which can effectively capture the damage behavior of materials under different loading conditions" were then calibrated using the Ramberg-Osgood model and stress-strain curve fitting. Image Pro Plus software v11.1 quantified the sample porosity as f0, fn, fc and fF. A finite element model was established to simulate the tensile behavior of the AISI 1035 steel samples. By comparing the damage parameters of f0, fn, fc and fF obtained by the finite element method and experimental method, the validity of the damage parameters obtained by the finite element inverse method could be verified.