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Keywords = oblique impact load

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20 pages, 3503 KiB  
Article
Finite Element Analysis Framework for Structural Safety Evaluation of Type IV Hydrogen Storage Vessel
by Gunwoo Kim, Hyewon Kim, Hanmin Park, Kyuhwan Park, Sujin Yoon, Hansu Lee, Seokjin Lee, Jonglyul Kim, Gyehyoung Yoo, Younggil Youn and Hansang Kim
Hydrogen 2025, 6(3), 44; https://doi.org/10.3390/hydrogen6030044 - 2 Jul 2025
Viewed by 298
Abstract
Type IV composite overwrapped pressure vessels (COPVs) store hydrogen at pressures up to 70 MPa and must meet stringent safety standards through physical testing. However, full-scale burst, plug torque, axial compression, impact, and drop tests are time-consuming and costly. This study proposes a [...] Read more.
Type IV composite overwrapped pressure vessels (COPVs) store hydrogen at pressures up to 70 MPa and must meet stringent safety standards through physical testing. However, full-scale burst, plug torque, axial compression, impact, and drop tests are time-consuming and costly. This study proposes a unified finite element analysis (FEA) workflow that replicates these mandatory tests and predicts failure behavior without physical prototypes. Axisymmetric and three-dimensional solid models with reduced-integration elements were constructed for the polyamide liner, aluminum boss, and carbon/epoxy composite. Burst simulations showed that increasing the hoop-to-axial stiffness ratio shifts peak stress to the cylindrical region, promoting a longitudinal rupture—considered structurally safer. Plug torque and axial load simulations revealed critical stresses at the boss–composite interface, which can be reduced through neck boss shaping and layup optimization. A localized impact with a 25 mm sphere generated significantly higher stress than a larger 180 mm impactor under equal energy. Drop tests confirmed that 45° oblique drops cause the most severe dome stresses due to thin walls and the lack of hoop support. The proposed workflow enables early-stage structural validation, supports cost-effective design optimization, and accelerates the development of safe hydrogen storage systems for automotive and aerospace applications. Full article
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21 pages, 14844 KiB  
Article
On the Design of Bionic Hierarchical H-Type Whip Restraints for Nuclear Power Plants
by Zheng He, Yuhang Yang, Libang Hu and Shuitao Gu
Appl. Sci. 2025, 15(10), 5507; https://doi.org/10.3390/app15105507 - 14 May 2025
Viewed by 390
Abstract
Whip restraints based on thin-walled structures are widely used for protection against high-energy pipe breaks in nuclear power plants due to their excellent impact resistance. Recently, biomimetic and hierarchical structures have emerged as focal points in thin-walled structure research, aimed at enhancing energy [...] Read more.
Whip restraints based on thin-walled structures are widely used for protection against high-energy pipe breaks in nuclear power plants due to their excellent impact resistance. Recently, biomimetic and hierarchical structures have emerged as focal points in thin-walled structure research, aimed at enhancing energy absorption capacities. Drawing inspiration from the nautilus shell and Fibonacci spiral, based on the nautilus bionic hierarchical multi-cell (NBHMC) structure, this study introduces a novel Nautilus Bionic Double Hierarchical Multi-Cell (NBDHMC) structure. Finite element analysis was employed to evaluate the energy absorption performance of the structure under axial and oblique loads using four crashworthiness parameters. Crashworthiness studies showed that the NBDHMC exhibits superior crashworthiness compared to the NBHMC and hollow circular tube configurations. Finally, the study investigated the influence of combination modes, hierarchical levels, cross-sectional characteristics, and other parameters on the parameterization of the NBDHMC. The results offer innovative insights for the design of highly efficient energy absorbers. Full article
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15 pages, 9276 KiB  
Article
Mechanical Response Mechanism and Yield Characteristics of Coal Under Quasi-Static and Dynamic Loading
by Liupeng Huo, Feng Gao and Yan Xing
Appl. Sci. 2025, 15(10), 5238; https://doi.org/10.3390/app15105238 - 8 May 2025
Viewed by 457
Abstract
During deep mining engineering, coal bodies are subjected to complex geological stresses such as periodic roof pressure and blasting impacts, which may induce mechanical property deterioration and trigger severe rock burst accidents. This study systematically investigated the mechanical characteristics and failure mechanisms of [...] Read more.
During deep mining engineering, coal bodies are subjected to complex geological stresses such as periodic roof pressure and blasting impacts, which may induce mechanical property deterioration and trigger severe rock burst accidents. This study systematically investigated the mechanical characteristics and failure mechanisms of coal under strain rates on two orders of magnitude through quasi-static cyclic loading–unloading experiments and split Hopkinson pressure bar (SHPB) tests, combined with acoustic emission (AE) localization and crack characteristic stress analysis. The research focused on the differential mechanical responses of coal-rock masses under distinct stress environments in deep mining. The results demonstrated that under quasi-static loading, the stress–strain curve exhibited four characteristic stages: compaction (I), linear elasticity (II), nonlinear crack propagation (III), and post-peak softening (IV). The peak strain displayed linear growth with increasing cycle, accompanied by a failure mode characterized by oblique shear failure that induced a transition from gradual to abrupt increases in the AE counts. In contrast, under the dynamic loading conditions, there was a bifurcated post-peak phase consisting of two unloading stages due to elastic rebound effects, with nonlinear growth of the peak strain and an interlaced failure pattern combining lateral tensile cracks and axial compressive fractures. The two loading conditions exhibited similar evolutionary trends in crack damage stress, though a slight reduction in stress occurred during the final dynamic loading phase due to accumulated damage. Notably, the crack closure stress under quasi-static loading followed a decrease–increase pattern with cycle progression, whereas the dynamic loading conditions presented the inverse increase–decrease tendency. These findings provide theoretical foundations for stability control in underground engineering and prevention of dynamic hazards. Full article
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19 pages, 5282 KiB  
Article
Shear Properties of the Interface Between Polyurethane Concrete and Normal Concrete
by Yuhan Zhang, Xinlong Yue, Zhengyi Liu, Boyang Mi, Lu Wang, Quansheng Sun, Xu Wang and Zhongnan Dai
Appl. Sci. 2025, 15(8), 4580; https://doi.org/10.3390/app15084580 - 21 Apr 2025
Viewed by 600
Abstract
Polyurethane concrete (PUC) is a promising candidate for structural repair materials due to its excellent mechanical properties and durability. However, the bonding performance between PUC and concrete interfaces may limit its broader application. This study examined the factors affecting the shear strength at [...] Read more.
Polyurethane concrete (PUC) is a promising candidate for structural repair materials due to its excellent mechanical properties and durability. However, the bonding performance between PUC and concrete interfaces may limit its broader application. This study examined the factors affecting the shear strength at the PUC–NC interface. A total of 16 oblique shear tests, varying by interface treatment methods (smooth—GH, roughened—ZM, and grooved—KC), adhesive application rates—NJJ (0, 0.2, and 0.3 kg/m2), and steel fiber contents—GXW (0%, 0.5%, 1%, and 1.5%), to evaluate their impact on the mechanical properties of the PUC–NC interface. The results demonstrated that roughening the interface significantly improved the shear strength, resulting in a 32% increase compared to a smooth interface and 15% compared to a grooved interface. A moderate adhesive application rate (0.2 kg/m2) enhanced the interface strength, while excessive adhesive did not further increase the shear strength. The optimal steel fiber content (1%) resulted in the highest shear strength, improving it by 22%, whereas excess steel fibers (1.5%) reduced the interface strength. This is due to fiber agglomeration, which weakens mechanical interlocking and introduces defects that impair interfacial bonding. Load–slip curve analysis revealed that roughened interfaces combined with the appropriate amount of steel fibers improved the interface toughness, delaying the failure process. This study presents a model for calculating the shear strength of steel fiber-reinforced PUC–NC interfaces, incorporating shear slip. Compared to existing models, it more accurately reflects the experimental data. Full article
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29 pages, 34281 KiB  
Article
Bio-Inspired Thin-Walled Straight and Tapered Tubes with Variable Designs Subjected to Multiple Impact Angles for Building Constructions
by Quanjin Ma, Nor Hazwani Mohd Yusof, Santosh Kumar Sahu, Yiheng Song, Nabilah Afiqah Mohd Radzuan, Bo Sun, Ahmad Yunus Nasution, Alagesan Praveen Kumar and Mohd Ruzaimi Mat Rejab
Buildings 2025, 15(4), 620; https://doi.org/10.3390/buildings15040620 - 17 Feb 2025
Cited by 3 | Viewed by 866
Abstract
Thin-walled structures are extensively utilized in construction because of their lightweight nature and excellent energy absorption efficiency, especially under dynamic loads. Improving the energy-absorbing performance of thin-walled structures by inspiring natural multi-cell designs is a sufficient approach. This paper investigates the energy-absorbing characteristics [...] Read more.
Thin-walled structures are extensively utilized in construction because of their lightweight nature and excellent energy absorption efficiency, especially under dynamic loads. Improving the energy-absorbing performance of thin-walled structures by inspiring natural multi-cell designs is a sufficient approach. This paper investigates the energy-absorbing characteristics of variable novel cross-section designs of thin-walled structures subjected to oblique impact loading. Straight and tapered types with seven cross-sectional designs of novel thin-walled structures were studied. The nonlinear ABAQUS/Explicit software 6.13 version was implemented to analyze the crashworthiness behaviors for the proposed variable cross-section designs under different loading angles. The crushing behaviors of the proposed thin-walled structures were examined for various wall thicknesses of 0.5 mm, 1.5 mm, and 2.5 mm and impact loading angles of 0°, 15°, 30°, and 45°. It was determined that the energy-absorbing characteristics of novel thin-walled structures can be efficiently controlled by varying two geometries and seven cross-section designs. A multi-criteria decision-making method (MCDM) using a complex proportional assessment method (COPRAS) was performed to select the optimum thin-walled structures with cross-section designs. It was shown that a tapered square thin-walled structure with 2.5 mm thickness had the best crashworthiness performances with energy absorption (EA) of 11.01 kJ and specific energy absorption (SEA) of 20.32 kJ/kg under a 30° impact angle. Moreover, the results indicated that the EA of the thin-walled structure decreased with the increase in the impact loading angle. In addition, with the increase in the impact loading angle, the peak crushing force (PCF) decreased and reflected the reduction in energy absorbed at a larger angle. The MCDM method in conjunction with the COPRAS method is proposed, it provides valuable insights for safer and more resilient building construction. Full article
(This article belongs to the Special Issue Bionic Materials and Structures in Civil Engineering)
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21 pages, 10566 KiB  
Article
Dynamic Responses of Single-Layer Reticulated Shells under Oblique Impact Loading
by Pengcheng Li, Guohan Chen, Hongxin Lu, Lu Ke, Hao Wang and Bin Jian
Buildings 2024, 14(3), 633; https://doi.org/10.3390/buildings14030633 - 28 Feb 2024
Cited by 6 | Viewed by 1500
Abstract
This paper focuses on the response of reticulated shell structures under oblique impact loads, with a departure from the traditional emphasis on vertical impact loads. These structures are typically utilised in large-span spaces such as iconic buildings and large venues. The study begins [...] Read more.
This paper focuses on the response of reticulated shell structures under oblique impact loads, with a departure from the traditional emphasis on vertical impact loads. These structures are typically utilised in large-span spaces such as iconic buildings and large venues. The study begins by establishing a numerical simulation method for reticulated shell structures subjected to oblique impact loads, which is then validated against existing experimental results. Building on this verified method, the research delves into the effects of varying impactor mass, velocity, and initial kinetic energy on the reticulated shell structure under oblique impacts, as well as the influence of different oblique impact angles. The study extensively examines the failure modes of the structure, node displacements in the structure, and variations in member stress under different impactor parameters. It further investigates how these parameters influence the maximum impact bearing capacity, impact duration, energy dissipation capability, and response forms of the structures, analyzing the reasons behind these effects. The findings offer valuable insights for further research and practical engineering design of reticulated shell structures. Full article
(This article belongs to the Special Issue Research on Recent Developments in Building Structures)
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15 pages, 4627 KiB  
Article
Investigating the Influence of All-Ceramic Prosthetic Materials on Implants and Their Effect on the Surrounding Bone: A Finite Element Analysis
by Saniya Juneja, Glynis Miranda, Afiya Eram, Nisha Shetty, Chethan K N and Laxmikant G. Keni
Prosthesis 2024, 6(1), 74-88; https://doi.org/10.3390/prosthesis6010006 - 17 Jan 2024
Cited by 9 | Viewed by 1905
Abstract
This study aims to assess and compare the impact of Monolithic Zirconia (MZ) and In-Ceram Zirconia (ZP) superstructures on stress distribution within implants and D2/D4 bone densities under 200 N vertical and oblique occlusal loads using three-dimensional finite element analysis via ANSYS WORKBENCH [...] Read more.
This study aims to assess and compare the impact of Monolithic Zirconia (MZ) and In-Ceram Zirconia (ZP) superstructures on stress distribution within implants and D2/D4 bone densities under 200 N vertical and oblique occlusal loads using three-dimensional finite element analysis via ANSYS WORKBENCH R2. The analysis employed maximum and minimum von Mises stress values. Modeling an implant (4.2 mm diameter, 10 mm length) and abutment (0.47 mm diameter), with an 8 mm diameter and 6 mm length single crown, the research identified lower von Mises stresses in D2 cancellous bone with the MZ model under vertical loading. Conversely, under oblique loading, the ZP model exhibited maximum von Mises stresses in D4 bone around the implant. This underscores the critical need to consider physical and mechanical properties, beyond mere aesthetics, for sustained implant success. The findings highlight the effect of material composition and stress distribution, emphasizing the necessity of durable and effective implant treatments. Full article
(This article belongs to the Collection Oral Implantology: Current Aspects and Future Perspectives)
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14 pages, 1586 KiB  
Article
Exploring 3D Pelvis Orientation: A Cross-Sectional Study in Athletes Engaged in Activities with and without Impact Loading and Non-Athletes
by Georgios Glakousakis, Perikles Kalatzis and Dimitris Mandalidis
J. Funct. Morphol. Kinesiol. 2024, 9(1), 19; https://doi.org/10.3390/jfmk9010019 - 4 Jan 2024
Viewed by 2745
Abstract
Female athletes subjected to various types of impact loading, especially over a long period of time, may experience changes in their pelvic orientation, which may affect their sport performance and increase the likelihood of injury. The aim of the present study was to [...] Read more.
Female athletes subjected to various types of impact loading, especially over a long period of time, may experience changes in their pelvic orientation, which may affect their sport performance and increase the likelihood of injury. The aim of the present study was to determine whether female athletes involved in high-impact loading sports (HILS), odd-impact loading sports (OILS), and repetitive non-impact loading sports (NILS) demonstrate changes in pelvis orientation compared to non-athletes (NATH). Pelvic orientation was determined using Euler/Cardan angles, calculated from the coordinates of the right, and left anterior superior iliac spines and pubic symphysis via a novel method. Two-way ANOVA tests showed significant differences between groups for pelvis position in the frontal plane (p < 0.05), with HILS and OILS demonstrating greater pelvic obliquity compared to NILS athletes and NATH. Significant main effects were also obtained for directions within the sagittal plane (p < 0.001). Significant within-group differences were observed in sagittal pelvic position among female athletes engaged in NILS (p < 0.01) and non-athletes (NATH) (p < 0.05), with a greater anterior pelvic tilt compared to posterior. Our findings suggest that pelvis orientation in female athletes across sports is influenced by sport-specific impact loads, potentially affecting performance and injury occurrence. Full article
(This article belongs to the Special Issue Advances in Musculoskeletal Physiotherapy)
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28 pages, 15648 KiB  
Article
Investigation of the Influence Area of the Excavation of a Double-Line Highway Tunnel under an Existing Railway Tunnel
by Yifan Li, Changfu Huang, Hongjian Lu and Chao Mou
Appl. Sci. 2024, 14(1), 290; https://doi.org/10.3390/app14010290 - 28 Dec 2023
Cited by 3 | Viewed by 1444
Abstract
The research on the impact of the excavation of underpass tunnels has already had certain results, but there is a lack of research cases of double-line highway tunnels with oblique angles under the existing railway tunnels, especially the method of determining the area [...] Read more.
The research on the impact of the excavation of underpass tunnels has already had certain results, but there is a lack of research cases of double-line highway tunnels with oblique angles under the existing railway tunnels, especially the method of determining the area of the impact of the dynamic and static loads of new tunnels and existing trains, which can be enriched by considering them at the same time. This paper, is based on the tunnel project of the new double-line Shiqian highway tunnel with oblique angles under the Hurong railway in Wanshoushan. By constructing a three-dimensional finite element model and simulating the application of static tunnel excavation load, dynamic blasting load, and dynamic train operation load of the existing tunnel, the overall displacement of the existing tunnel and the settlement value of the bottom plate of the track surface by the static tunnel excavation load were analyzed. Then, the stresses, vibration speeds, and displacements of the tunnel due to the dynamic blasting loads and the dynamic train operation loads were obtained. The results show that the area of influence of the static loads of the new tunnel excavation on the existing tunnel is divided into three types of perturbations presenting strong, weak, and slight; the area affected by the blasting dynamic load of new tunnel excavation is a circular domain with the datum point in the tunnel section as the center; the area affected by the dynamic load of train operation in the existing tunnel is an ellipse with the center of the track surface of the existing tunnel as the datum; and there is an anomalous shape in the area affected by the blasting dynamic load of new tunnel excavation and the area affected by the dynamic load of the train operation in the existing tunnel. Full article
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14 pages, 3745 KiB  
Article
Wind-Induced Responses of Corroded Angle-Steel Transmission Tower
by Ligang Zhang, Yuan Ren, Xing Zhou, Guohui Shen, Zhibin Tu and Jianfeng Yao
Energies 2023, 16(14), 5429; https://doi.org/10.3390/en16145429 - 17 Jul 2023
Cited by 4 | Viewed by 1439
Abstract
Corroded transmission towers, whose load-bearing capacities are lowered, are suffering from wind-induced damage. By simulating the member corrosion through section thinning, the structural dynamic finite element model of an angle-steel transmission tower with a corrosion depth of 0 mm to 1.4 mm was [...] Read more.
Corroded transmission towers, whose load-bearing capacities are lowered, are suffering from wind-induced damage. By simulating the member corrosion through section thinning, the structural dynamic finite element model of an angle-steel transmission tower with a corrosion depth of 0 mm to 1.4 mm was established using ANSYS/LS-DYNA software. The incremental dynamic analysis method was used to study the collapse mode of the tower under different degrees of corrosion, as well as the effects of corrosion on structural self-vibration characteristics, wind-induced member stress, and tower-top displacement. The results show that with the corrosion deepening, the first three vibration frequencies decrease, and the torsional mode becomes the first mode. When the corrosion depth is smaller, the overall structure failure occurs under strong wind. The failure starts at the most unfavorable oblique rod between the upper and middle cross arm, then expands to the rods under the lower cross arm. When the corrosion depth is larger, the overall structure failure occurs restrictedly between the upper and middle cross arm. Internal axial force and bending moment redistribution happen when corrosion deepens. Under the critical failure state, the oblique rods are always at a high stress level, while the stresses of the main rods decrease. Corrosion has a stronger impact on component strength and stability than on structural stiffness. Full article
(This article belongs to the Section A3: Wind, Wave and Tidal Energy)
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17 pages, 4463 KiB  
Article
Oblique Crashworthiness Analysis of Steel Circular Tubes: Parametric Study on Wall Thickness Effect and Critical Loading Angle Identification
by Konstantina D. Karantza, Ioannis G. Papantoniou, Stavros S. A. Lykakos and Dimitrios E. Manolakos
Machines 2023, 11(5), 542; https://doi.org/10.3390/machines11050542 - 11 May 2023
Cited by 2 | Viewed by 2274
Abstract
The current work studied the crashworthiness behavior of thin-walled circular steel tubes against axial and oblique crushing. Parametric analyses of crushing angle and tube wall thickness were conducted aiming to identify their effect on dissipated energy, collapse initiation and deformation stability. Quasi-static experiments [...] Read more.
The current work studied the crashworthiness behavior of thin-walled circular steel tubes against axial and oblique crushing. Parametric analyses of crushing angle and tube wall thickness were conducted aiming to identify their effect on dissipated energy, collapse initiation and deformation stability. Quasi-static experiments and finite element (FE) simulations in LS-DYNA were implemented for crushing angle parametric analysis, while the wall thickness effect was studied numerically for the same loading angle range. Both experiments and simulations revealed that an increase in crushing angle results in lower energy absorption (EA) and peak force. Low-angled oblique loading was indicated as the most efficient impact condition reaching sufficient EA and facilitating plastic collapse initiation. The occurrence of global bending mode revealed a critical loading angle value reacting to a significant EA drop due to unstable plastic deformation. Finally, higher wall thickness resulted in greater peak force and increased critical angle reacting to a smoother EA decrease with respect to loading angle by preventing unstable deformation mode. Full article
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21 pages, 14239 KiB  
Viewpoint
Mechanism and Control of Asymmetric Floor Heave in Deep Roadway Disturbed by Roof Fracture
by Wensheng Wei, Guojun Zhang, Chunyuan Li, Wenshuai Zhang and Yupeng Shen
Sustainability 2023, 15(8), 6357; https://doi.org/10.3390/su15086357 - 7 Apr 2023
Cited by 4 | Viewed by 1470
Abstract
In view of the serious problem of bottom-drum damage in deep mining along empty roadways, the asymmetric bottom-drum damage characteristics and control mechanisms of deep mining along an empty roadway were studied using the trackway of the 11060 working face in Zhao Gu [...] Read more.
In view of the serious problem of bottom-drum damage in deep mining along empty roadways, the asymmetric bottom-drum damage characteristics and control mechanisms of deep mining along an empty roadway were studied using the trackway of the 11060 working face in Zhao Gu II mine as the research background. Based on the slip-line theory, support-pressure distribution law, and Griffith’s damage-criterion theory, the mechanism of asymmetric bottom drums and the maximum fracture-development depth of the bottom plate in a deep roadway under top-plate fracture perturbation were analyzed. The 3DEC discrete-element software was used to simulate and analyze the characteristics and evolution of the asymmetric bottom bulge of the roadway under dynamic-load disturbance, and the asymmetric control scheme of “slurry anchor reinforcement + top cutting and pressure relief” was proposed. The results show that, under the influence of static load of deep high-abutment pressure and the dynamic-load impact of the instability of the masonry-beam structure under periodic pressure of the adjacent working face, the deep-mining goaf roadway was prone to producing asymmetric floor heave. The floor-heave degree and maximum fracture-development range of the roadway in the affected area under the influence of dynamic load > those in goaf roadway > those in the roadway in the stable area affected by tunneling. The distribution of stress, displacement, and maximum floor heave was skewed to the side of the coal pillar in the goaf, showing an inverted right oblique V shape. The asymmetric floor heave of a roadway can be effectively controlled by grouting anchor-cable reinforcement (increasing the anti-damage limit) and roof-cutting pressure relief (cutting off the dynamic-load source). The research results can provide an important reference for the control of roadway floors under similar geological conditions. Full article
(This article belongs to the Special Issue Sustainable Mining and Emergency Prevention and Control)
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21 pages, 4307 KiB  
Article
Kinematics Modeling and Singularity Analysis of a 6-DOF All-Metal Vibration Isolator Based on Dual Quaternions
by Chao Zheng, Luming Zou, Zhi Zheng and Xin Xue
Symmetry 2023, 15(2), 562; https://doi.org/10.3390/sym15020562 - 20 Feb 2023
Cited by 5 | Viewed by 2465
Abstract
Driven by the need for impact resistance and vibration reduction for mechanical devices in extreme environments, an all-metal vibration isolator with 6-degree-of-freedom (6-DOF) motion that is horizontally symmetrical was developed. Its stiffness and damping ability are provided by oblique springs in symmetrical arrangement [...] Read more.
Driven by the need for impact resistance and vibration reduction for mechanical devices in extreme environments, an all-metal vibration isolator with 6-degree-of-freedom (6-DOF) motion that is horizontally symmetrical was developed. Its stiffness and damping ability are provided by oblique springs in symmetrical arrangement and a metal–rubber elasto-porous damper. The spring is symmetrically distributed in the center axis of the support load surface. It is necessary to investigate the kinematics and the singularity before conducting multi-body dynamics analysis of the vibration isolator. Based on the theory of dual quaternions, the forward kinematics equations of the isolator were successively derived for theoretical kinematics modeling. In addition, an enhanced Broyden numerical iterative algorithm was developed and applied to the numerical solution of the forward kinematics equations of the vibration isolator. Compared with the traditional rotation-matrix method and Newton–Raphson method, the computational efficiency of the enhanced Broyden numerical iterative algorithm was increased by 680% and 290%, respectively. This was due to the enhanced algorithm without the calculations of any inverse matrix and forward kinematics equations. Finally, according to the forward kinematics Jacobian matrix, the position-singularity trajectory at a given orientation and the orientation-singularity space at a given position are calculated, which provides a basis for the algorithm of the 6-DOF vibration isolator to avoid singular positions and orientations. Full article
(This article belongs to the Special Issue Symmetry and Asymmetry in Composite Materials and Its Applications)
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21 pages, 7951 KiB  
Article
Crashworthiness Analysis of Square Aluminum Tubes Subjected to Oblique Impact: Experimental and Numerical Study on the Initial Contact Effect
by Konstantina D. Karantza and Dimitrios E. Manolakos
Metals 2022, 12(11), 1862; https://doi.org/10.3390/met12111862 - 1 Nov 2022
Cited by 13 | Viewed by 2587
Abstract
This study investigates the crashworthiness behavior of square aluminum thin-walled tubes subjected to both axial and oblique impact loading, emphasizing the effects of crushing angle and initial contact between impactor and tube on the plastic collapse initiation and energy absorption capacity. A parametric [...] Read more.
This study investigates the crashworthiness behavior of square aluminum thin-walled tubes subjected to both axial and oblique impact loading, emphasizing the effects of crushing angle and initial contact between impactor and tube on the plastic collapse initiation and energy absorption capacity. A parametric study in crushing angle is conducted until 15°, while the two examined types of initial contact between impactor and tube consist of a contact-in-edge case and a contact-in-corner one, aiming to capture the effect of initial contact on both plastic collapse and energy absorption. Both experimental quasi-static tests and numerical simulation via finite element modeling in LS-DYNA software are carried out for the evaluation of the crushing response of the tested tubes. The 5° oblique cornered crushing revealed the greatest energy absorption, reflecting the most efficient loading case as significant tearing failure occurred around the tube corners in axial crushing due to a higher peak crushing force, while the increase in crushing angle caused a drop in energy absorption and peak force regarding the oblique loading. Finally, an initial contact-in-corner case revealed higher energy absorption compared to both axial and edged oblique loading, while peak force showed a slight decrease with crushing angle in that case. Full article
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22 pages, 8833 KiB  
Article
Seismic Response of Immersed Tunnel Subject to Oblique Incidence of SV Wave
by Cong He, Guoyuan Xu, Zhigang Zhang and Wei Li
Appl. Sci. 2022, 12(20), 10440; https://doi.org/10.3390/app122010440 - 16 Oct 2022
Cited by 4 | Viewed by 2062
Abstract
In view of the near-field seismic action, considering that oblique incidence of seismic waves is more realistic than vertical incidence, the seismic response of the Hong Kong–Zhuhai–Macao immersed tunnel subjected to an obliquely incident SV wave is investigated. Using the finite element method [...] Read more.
In view of the near-field seismic action, considering that oblique incidence of seismic waves is more realistic than vertical incidence, the seismic response of the Hong Kong–Zhuhai–Macao immersed tunnel subjected to an obliquely incident SV wave is investigated. Using the finite element method and time-domain wave method, the seismic input is transformed into an equivalent node load with a viscous–spring artificial boundary, and a three-dimensional simulation technology for SV waves of oblique incidence is presented. A half-space numerical example is given to demonstrate the accuracy of the proposed simulation technology. Taking the stress field formed by the self-weight stress and hydrostatic pressure as the initial state of the dynamic response analysis, the static–dynamic coupling numerical simulation of the seismic response of a soil-immersed tunnel system is realized. The results show that the amplification in the vertical and longitudinal response of the tunnel, due to the oblique incidence, reaches maximum when the incident angle is close to the critical angle. Furthermore, the horizontal response and incident angle show the inverse relation and tend to be stable. In addition, the oblique incidence also causes asymmetric shearing in symmetric parts of the tunnel. The root of the shear key easily produces tensile cracks, while the end angle of the shear key is prone to stress concentration and local damage. Thus, the impact of oblique incidence should be considered in the seismic design, and attention should be paid to the optimization of the end angle of the shear key and the configuration of anti-crack reinforcement at the root of shear key to meet the seismic requirements. Full article
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