Search Results (349)

Hydraulic synchronous jacking technology is extensively employed in bridge reconstruction and new construction, with jacking supports serving as core components whose blast resistance is critical to the structural safety of the bridge jacking system. This study numerically investigates the dynamic response and damage behavior of bridge jacking supports subjected to under-deck gas explosion loading through the finite-element software LS-DYNA. The TNT equivalent method is adopted to convert gas explosion load into equivalent TNT detonation load for simulation, and the effects of TNT detonation location on the blast-resistance performance of the jacking support are analyzed. The results indicate that the bridge segment temporarily loses contact with the jacking support under the action of gas explosion loading. The bridge segment around the web plate undergoes shear damage because of the deformation constraint effect of the web plate. The shear damage level of the bridge segment increases with the increase in TNT mass. The displacement of the jacking support increases with the increase in the mass of the explosive. The enhanced rod around the edge steel pipe support is more prone to damage due to its low local stiffness. The damage level of the bridge segment increases with the decrease in the distance between the TNT detonation and the bridge segment, and then the blast-resistance performance of the jacking support is almost unrelated to the vertical distance. The transverse distance between the TNT detonation and the jacking support has a significant effect on the response of jacking support. Full article

Housner’s classical rocking model assumes a rigid base, which often leads to inaccurate seismic assessments under real–world soil conditions. This study quantitatively establishes the applicability limits of the rigid–base assumption and defines a reference range for its validity. To address these limitations, a novel soil–structure interaction (SSI) rocking model was developed using Lagrange’s formulation, incorporating an event–driven spring–dashpot mechanism to characterize contact forces. Validation against LS–DYNA simulations and existing compliant base models confirms high predictive accuracy across diverse geometries and ground motions. Crucially, an empirical formulation for the interface stiffness of rocking structures was derived to ensure the alignment of the proposed analytical model with numerical observations, thereby enhancing its practical utility in industrial design. Our findings reveal that rocking behavior depends not only on soil stiffness but also on the inherent stiffness of the structure. Specifically, soft soils significantly alter rocking initiation thresholds and amplify peak angles. The proposed SSI–rocking model provides a computationally efficient and FE–compatible tool for optimizing the seismic stability of unanchored structures on flexible foundations. Full article

Numerous factors influence the formation of blasting craters in engineering blasting. Based on the actual parameters of the Daye Iron Mine, this study established six sets of single-hole blasting crater numerical models with different borehole diameters using ANSYS(19.0)/LS-DYNA(R13) software. The variation in blasting crater volume with the scaled depth was analyzed to determine the optimum scaled depth for each borehole diameter, and a functional relationship between the optimum scaled depth and borehole diameter was derived through curve fitting. Furthermore, using a borehole diameter of 0.076 m as a case study, a double-hole blasting crater was developed to investigate the effect of varying hole spacing on blasting crater volume and to determine the optimal hole spacing. The blasting parameters were optimized based on the numerical simulation results. The results show that within the range of borehole diameters considered, the blasting crater volume initially increases and then decreases with increasing scaled depth of the explosive charge. The fitted relationship between the optimum scaled depth and borehole diameter is y = −180.7197x³ + 86.3754x² − 9.5504x + 1.0782. For a borehole diameter of 0.076 m, the optimum scaled depth is 0.7278 m/kg^1/3, and the optimal hole spacing is 0.52 m. Based on blasting similarity theory, the calculated optimum burial depth of the explosive charge is 0.59 m, the critical burial depth is 1.1 m, and the recommended row spacing ranges from 0.95 m to 1.18 m. The findings of this study provide a theoretical basis for optimizing blasting parameters at the Daye Iron Mine and similar mining operations. Full article

Rapid advances in on-orbit servicing technologies have driven exponential growth in micro-spacecraft on-orbit ejection missions. Post-separation attitude disturbances are the dominant factor determining mission success, requiring accurate and rapid disturbance prediction. This study develops an efficient multi-rigid-body dynamic simulation framework for on-orbit ejection based on the simulation software ADAMS. Contact parameters between the micro-spacecraft and guide rail are calibrated against high-fidelity rigid–flexible coupled simulation results from the simulation software LS-DYNA, establishing a streamlined simulation pipeline. Using this validated framework, the effects of thrust misalignment angle, thrust eccentricity, and mass eccentricity on ejection-phase attitude disturbances are systematically quantified. Results demonstrate that the calibrated ADAMS multi-rigid-body model effectively substitutes computationally intensive rigid–flexible coupled models without sacrificing predictive accuracy. Specifically, constraining the axial thrust misalignment angle to ≤0.2°, axial thrust eccentricity to ≤0.4 mm, and axial mass eccentricity to ≤0.2 mm can significantly enhance separation attitude stability. This work provides a practical and efficient engineering methodology for the rapid assessment of attitude disturbances in micro-spacecraft on-orbit ejection systems. However, this study is limited to analyzing the ejection phase of separation, neglecting attitude disturbance effects in the subsequent orbital flight and target impact phases. Future work will address these omissions by extending the model to the entire mission profile and quantifying associated uncertainties. Full article

Aerospace canopies require both high impact resistance and optical transparency for pilot safety and aerodynamic shielding. While polycarbonate (PC) and poly(methyl methacrylate) (PMMA) are widely utilized, their vulnerability to strain-rate-dependent failure during high-velocity bird strikes necessitates advanced reinforcement strategies. This study presents a multiscale computational framework for nanoparticle-reinforced PC nanocomposites. To circumvent the prohibitive computational costs of atomistic simulations, a novel Strain-Rate Dependent Micromechanics (SRDM) framework is proposed for silica-, alumina-, and zirconia-reinforced PC systems, integrating the Goldberg constitutive model with Halpin–Tsai micromechanics to generate rate-dependent stress–strain responses and calibrate Johnson–Cook (J-C) parameters for impact-scale simulations. Unlike conventional approaches relying on atomistic simulations or empirical fitting, the proposed framework directly links micromechanical nanocomposite modeling with finite element bird-strike simulations. Bird-strike analyses were performed in LS-DYNA on a generic fighter canopy model. The framework further incorporates literature-based optical transparency criteria considering nanoparticle size and refractive-index compatibility. Among the investigated nanofillers, silica-reinforced PC provided the most favorable response. At the most critical impact location, the maximum canopy deformation decreased from 118.6 mm for neat PC to 61.9 mm, corresponding to an approximately 48% reduction. Although the reinforced canopy exhibited a reduction in peak internal energy absorption from approximately 10 kJ to 5 kJ due to its increased stiffness and reduced plastic deformation, it provided improved deformation resistance and structural stability under impact loading. Overall, this work provides a computationally efficient framework for designing bird-strike-resistant transparent nanocomposite canopy structures using nanofiller systems previously reported in the literature to preserve optical transparency. Full article

To investigate the effect of scribing wheel angle on the scribing behavior of LCD glass, an SPH-based numerical model was established in LS-DYNA and validated against experimental results for reaction force and median crack depth. The results show that the model can accurately capture the mechanical response and crack propagation during the scribing process. At a scribing depth of 10 μm, the maximum relative errors between simulation and experiment were 5.17% for reaction force and 2.36% for median crack depth. The results for the 110° scribing wheel indicate that median cracks mainly initiate and propagate rapidly during the penetration stage, while the median crack depth becomes nearly stable after the preset depth is reached, and the subsequent rolling stage has little influence on further crack growth. As the wheel angle increases from 90° to 140°, the experimental mean peak reaction force increases from 2.66 N to 9.97 N, the maximum effective stress increases from 374.4 MPa to 732.8 MPa, and the median crack depth increases from 68 μm to 97 μm. Experimental observations further show that small wheel angles tend to cause debris accumulation and edge chipping, whereas excessively large wheel angles are likely to induce lateral cracks. Overall, a wheel angle of about 110° provides better cross-sectional quality, surface quality, and crack controllability for 0.2 mm-thick LCD glass. Full article

Rockfall is one of the most dangerous and unpredictable natural disasters that can seriously damage infrastructure. In traditional protection systems, sand is commonly used as a buffer material; however, the use of large sandbags as temporary protective structures has still not been investigated, and there are no established design guidelines available. This study aims to reveal the effect of rockfall impact on the dynamic response of a sandbag protection system for temporary restoration work in the event of a natural disaster. Initially, a numerical model based on finite element calculation was adopted to simulate the large sandbags under rockfall impact, which was verified by the full-scale experimental test data. The parameters identified were impactor velocity, acceleration, penetration depth, and sandbag displacement. After validation, the model was used for prediction analysis to examine the dynamic response and energy absorption characteristics of sandbags under different conditions, such as the influence of sand density, impactor velocity, impact height and the number of sandbags in the impact direction. The results propose an analytical basis for the establishment of performance-based guidelines for the design of sandbag walls as a temporary rockfall protection system. Full article

As primary structural components, the damage characteristics and failure modes of reinforced concrete (RC) beams under near-field blast loads are essential for blast-resistant design and vulnerability analysis. To address the research gap regarding the failure modes and blast performance of RC beams under eccentric explosions, this study systematically investigates the effects of charge mass and eccentric distance on structural damage. This was achieved through three near-field air blast tests with varying charge masses and explosion locations, supplemented by LS-DYNA numerical simulations. The experiments utilized 1/2-scale RC beam specimens, and the numerical simulations were conducted using the ALE fluid–structure interaction (FSI) algorithm. A classification criterion for beam failure modes was established using a deformation decoupling method, based on the shear deformation ratio (δ). Results indicate that under eccentric explosions that do not trigger significant local damage, the beams primarily exhibit global deformation. Under a charge mass of 2 kg TNT, as the eccentric distance (e) increases from 0 (mid-span) to 0.90 m, the maximum vertical displacement of the RC beam decreases from 3.50 cm to 1.37 cm (a reduction of approximately 60%). The shear deformation ratio δ at the point of maximum displacement first decreases from 0.3117 at mid-span to a minimum of 0.0670 at e = 0.90 m, then rises to 0.2635 at e = 1.05 m, exhibiting a clear “V-shaped” trend. Increasing the charge mass from 2 kg to 2.5 kg for mid-span explosions raises the maximum displacement from 3.50 cm to 8.22 cm (an increase of 135%) and causes δ to increase from 0.3117 (flexural-shear failure) to 0.4428 (shear-like failure). The inflection point of the “V-shaped” δ curve shifts inward from e = 0.90 m (2 kg) to approximately e = 0.45 m (2.5 kg), indicating a transition toward shear-dominated failure modes with increasing charge mass. As the equivalent increases, the failure mode gradually shifts toward a shear-dominated mode, and the inflection point of the deformation ratio shifts toward the mid-span. These findings provide a theoretical foundation and technical support for the damage assessment and blast-resistant design of RC structures. Full article

Masonry structures are widely used in civil engineering due to their favorable load-bearing capacity and construction efficiency; however, the threat posed by long-duration blast loads from industrial accidents and large-yield explosions has become increasingly prominent. Existing research has primarily focused on the response of masonry walls under conventional short-duration explosions, while systematic investigations remain limited regarding the differentiated failure mechanisms induced by long-duration blasts. To address this gap, this study adopts and validates a full-scale simplified micro-modeling approach for clay brick masonry walls using LS-DYNA. The model enables systematic comparison of long-duration blast loads and conventional blast loads simulated by the CONWEP method under equal peak overpressure and equal impulse conditions. Numerical results indicate that, under equal peak overpressure (0.18 MPa), the long-duration blast load induces global deformation and cumulative damage leading to complete collapse, whereas the conventional blast load results in only elastic response. Under equal impulse (13.5 kPa·s), both loads cause severe damage, yet the conventional blast load triggers instantaneous localized fragmentation with a higher collapse rate, while the long-duration blast load governs failure through sustained overpressure-induced global deformation and crack propagation. The comparison of mid-span displacement–time histories across different loading cases further quantifies these distinct failure modes, revealing fundamentally different deformation development rates and collapse characteristics. The key contributions of this study are summarized as follows: A validated simplified micro-model is developed that reproduces the experimental damage patterns of masonry walls. A comparison identifies and mechanistically explains the differentiated failure modes between the two load types. Under the conditions considered in this study, critical transition thresholds of peak overpressure and impulse governing the damage mode shift from minor cracking to global collapse are determined. These findings provide a scientific basis for distinguishing blast-resistant design strategies for masonry structures according to explosion type. Full article

The crushing failure of sea ice is a critical design issue for polar offshore structures and ship structures because ice-induced loads may generate pronounced local damage and dynamic responses. Accurately modelling this process remains challenging because ice crushing involves localized fragmentation, crack propagation, rubble accumulation, and repeated contact release. This paper presents a controlled numerical sensitivity study of level-ice crushing against a vertical structure using a coupled LS-DYNA framework that combines the Structured Arbitrary Lagrangian–Eulerian (S-ALE) formulation with the Cohesive Element Method (CEM). The study focuses on a benchmark-scale indentation configuration and examines how mesh topology, mesh size, and imposed indentation velocity affect the predicted fracture morphology and load-time histories. The results show that random triangular meshes better reproduce stochastic fragmentation and lateral flaking than regular triangular or quadrilateral meshes, while finer meshes reduce excessive load oscillations and provide more stable force histories. The velocity study indicates a transition from gradual crushing and fragment retention at lower velocities to more rapid brittle chipping and stronger dynamic fluctuations at higher velocities. A benchmark-level comparison with published ice-indentation simulations shows that the predicted peak line load is of the same order of magnitude as reference results. The proposed framework is therefore useful for investigating numerical sensitivities and failure-mode trends in ice-crushing simulations, although final design-load application requires further calibration and formal mesh-independence assessment. Full article

In winter, ice readily accretes on the HDPE sheath of stay cables, creating shedding hazards and exacerbating wind-induced vibrations, thereby threatening bridge and traffic safety. Cable-climbing de-icing devices have been proposed to replace manual operations, yet their performance is often limited by climbing instability caused by abrupt changes in cable-surface friction. This study develops a quadrotor-driven stay-cable de-icing device that integrates an arc-shaped milling wheel with an embedded heating module to realize thermo-mechanically coupled de-icing. The device climbs via rotor-generated aerodynamic lift and performs continuous top-down de-icing using gravity-assisted motion together with rotor thrust. Laboratory tests and ANSYS LS-DYNA explicit dynamic simulations are conducted to quantify the effects of clamping force and axial thrust on the ice removal ratio in a purely mechanical mode. In addition, a three-stage experimental campaign—temperature-rise, thermo-mechanical de-icing, and thermal-balance tests—is carried out to verify heating feasibility and to examine the roles of heating power and initial wheel temperature. The results indicate that, under purely mechanical de-icing, the ice removal ratio increases monotonically with clamping force and thrust but gradually approaches saturation. Under thermo-mechanical de-icing, higher heating power and initial temperature improve removal performance. Notably, thermo-mechanical de-icing under low thrust achieves a higher removal level than purely mechanical de-icing under high loads, demonstrating improved effectiveness and engineering practicality. An initial equivalence relationship between mechanical parameters and temperature is established to support further optimization. Full article

A study was conducted on the interaction of surface gravity waves with a relatively thin, free-floating ice floe compared to the height of the waves. Physical and numerical modeling, as well as analytical research, were used. An overview of scientific works on the research topic is presented. The physical model consisted of an experimental setup (wave flume) with a wooden plate exposed to gravitational harmonic waves of different lengths and periods. The numerical model is based on calculations performed in the LS-DYNA program, where the fluid was simulated using the Euler–Lagrange method, and solid bodies were considered rigid. Analytical studies use the theory of interaction of small-amplitude waves with floating breakwaters. It is shown that as the wave height increases for conditions of interaction between waves and ice floes of almost identical horizontal dimensions, one end of the floating body sinks into the water, which leads to a significant reduction in the drift speed of the ice floe. Formulas have been obtained that express the ratio of the ice floe’s speed to the wave velocity, as well as the ratio of the height of the incident waves to the height of the transmitted waves, depending on the ratio of the wavelength to the horizontal dimensions of the floating ice floe. Full article

Supercritical CO₂ gas explosion is an important technique for enhancing permeability in low-permeability coal seams, as it can improve gas drainage efficiency while avoiding the open-flame hazards of conventional explosion and the high water consumption associated with hydraulic fracturing. This study aims to reveal the crack propagation patterns and stress-wave dynamics under different hole configurations. Using LS-DYNA, fracture models were established for three configurations under supercritical CO₂ explosions: single-hole, symmetrical double-hole, and symmetrical double-hole with a control hole. The fracture processes were analyzed to investigate the effective fracture radius of single-hole explosions, the optimal spacing for symmetrical double-hole explosions, and the influence of control holes on crack development and connectivity. The simulation results indicate that the effective fracture radius of a single-hole explosion reaches up to 2.6 m under the modeled conditions. Compared with the single-hole gas explosion case, the symmetrical double-hole configuration with a spacing of 7 m significantly enhances fracture interaction and connectivity, resulting in an approximately 98% increase in the effective damaged area. Permeability enhancement was further quantified by introducing a damage–permeability mapping (k/k₀) based on the simulated damage factor, and the permeability-enhanced zone was evaluated using the criterion of k/k₀ ≥ 2. Full article

Conventional uniform-thickness expansion-tube energy-absorbing structures suffer from excessively high initial peak crushing forces (IPCFs) and sub-optimal energy absorption efficiency. Inspired by the gradient stiffness characteristics of the inter node-to-node structure in Buddha’s Belly Bamboo, this study proposed an expansion-tube energy-absorbing structure design featuring a gradient stiffness. An LS-DYNA finite element simulation model was first established, validated through experimental results, and subsequently subjected to multi-objective optimization. The analysis results demonstrate that the stiffness-gradient expansion-type energy-absorbing structure designed in this study not only effectively reduces the IPCF during energy absorption but also further enhances its buffering and specific energy absorption (SEA). Full article

Bird strike events on rotating jet engine fan blades pose significant risks to aviation safety, yet high-fidelity numerical simulations remain computationally expensive, limiting their use in parametric design studies. This study develops a physics-guided machine learning surrogate framework for predicting bird strike response on rotating Ti-6Al-4V fan blades, systematically comparing Lagrangian (gelatin-based, Mooney–Rivlin) and Smoothed Particle Hydrodynamics (SPH, water-like) formulations. A total of 100 explicit dynamic simulations were conducted in ANSYS LS-DYNA (R2) (50 per formulation), varying bird impact velocity and blade angular speed. Random Forest, Support Vector Regression, Polynomial Regression, and XGBoost regression models were trained and evaluated using five-fold cross-validation. Results demonstrate that SPH-based surrogates achieve superior predictive accuracy, with Random Forest yielding R² = 0.9938 for maximum deformation and R² = 0.9962 for total energy dissipation. In contrast, Lagrangian-based stress surrogates exhibited severe performance degradation (R² = 0.24) due to mesh-dependent numerical noise. The trained surrogates achieved computational speed-up factors of 10⁴–10⁵ relative to direct simulation. These findings establish that surrogate model reliability is fundamentally governed by the numerical quality of the training data, providing guidance for integrating machine learning with impact simulation workflows in aero-engine blade design. Full article