Numerical research on impact performance of bridge columns with aluminum foam protection devices

This article presents a new protection device using aluminum foam to enhance the impact resistance of bridge columns. First, the protection device is designed according to the characteristics of aluminum foam material. The geometric configuration and structure of the device are described. Second, the impact performance of bridge column is analyzed, including impact force analysis, damage analysis, and the influence of axial load. Third, three-dimensional solid element models of columns with and without the protection device are developed in order to verify the effect of the protection device. By comparing dynamic responses of vehicle impact on columns with and without the protection device, it is considered that the protection device has certain protection effect: after installing the protective device, the peak value of impact force reduces by 37.5%, the maximum displacement of column top reduces by 23.7%, the maximum stress at column bottom reduces by 51.6%, the maximum stress at column bottom reduces by 51.6%, the maximum acceleration of the vehicle reduces by 40.6%, and 86.84% of the impact energy is absorbed by the protection device. Finally, the devices with different foam thicknesses and porosities are comparatively analyzed to investigate the influence of these design parameters on impact performance. The results show that the increase in the thickness of aluminum foam has positive effects on the protection capability. The protection capability improves with aluminum foam porosity increasing when the porosity is less than 60%.

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Effect of Abrasive Concentration on Impact Performance of Abrasive Water Jet Crushing Concrete

Shock and Vibration ◽

10.1155/2019/3285150 ◽

2019 ◽

Vol 2019 ◽

pp. 1-18

Author(s):

Xiaohui Liu ◽

Ping Tang ◽

Qi Geng ◽

Xuebin Wang

Keyword(s):

Internal Energy ◽

Impact Force ◽

Abrasive Particle ◽

Water Jet ◽

Abrasive Water Jet ◽

Sph Method ◽

Impact Performance ◽

Water Jets ◽

The Impact ◽

Peak Impact Force

It has been found that the impact performance of water jets can be changed by its properties, which include pressure, additive, and mode of jet. Thus, an abrasive water jet (AWJ) has been developed as a new method. However, there is little research on the effect of abrasive concentration on the impact performance of abrasive jets. Thus, the SPH method is used to establish an abrasive water jet crushing concrete model to study the effect of abrasive concentration on the impact force, concrete internal energy, abrasive particle distribution, crushing depth, and damage and crushing efficiencies under different concrete compressive strengths and abrasive densities. The results indicate that there is little effect of the abrasive concentration on the peak impact force under different compressive strengths and abrasive densities, while the mean impact force tends to increase linearly with the abrasive concentration. The internal energy of the concrete increases stepwise with the abrasive concentration under different compressive strengths and abrasive densities. The concentration of 10%∼20% is the rapid increasing stage. The crushing depth and damage efficiencies are all maximum at a concentration of 20% under different compressive strengths and abrasive densities. After the concrete was impacted by the water from the water jet, it is divided into rebounding particles and intrusive particles. The more the intrusive particles, the easier the concrete to be crushed and damaged.

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A Comparative Study on the Effect of Mechanical Compliance for a Safe Physical Human–Robot Interaction

Journal of Mechanical Design ◽

10.1115/1.4046068 ◽

2020 ◽

Vol 142 (6) ◽

Cited By ~ 1

Author(s):

Yu She ◽

Siyang Song ◽

Hai-Jun Su ◽

Junmin Wang

Keyword(s):

Impact Force ◽

Variable Stiffness ◽

Human Robot Interaction ◽

Design Parameters ◽

Robot Dynamics ◽

Robot Interaction ◽

Promising Alternative ◽

Mechanical Compliance ◽

Maximum Impact Force ◽

The Impact

Abstract In this paper, we study the effects of mechanical compliance on safety in physical human–robot interaction (pHRI). More specifically, we compare the effect of joint compliance and link compliance on the impact force assuming a contact occurred between a robot and a human head. We first establish pHRI system models that are composed of robot dynamics, an impact contact model, and head dynamics. These models are validated by Simscape simulation. By comparing impact results with a robotic arm made of a compliant link (CL) and compliant joint (CJ), we conclude that the CL design produces a smaller maximum impact force given the same lateral stiffness as well as other physical and geometric parameters. Furthermore, we compare the variable stiffness joint (VSJ) with the variable stiffness link (VSL) for various actuation parameters and design parameters. While decreasing stiffness of CJs cannot effectively reduce the maximum impact force, CL design is more effective in reducing impact force by varying the link stiffness. We conclude that the CL design potentially outperforms the CJ design in addressing safety in pHRI and can be used as a promising alternative solution to address the safety constraints in pHRI.

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Simulations and Tests of Composite Marine Structures Under Low-Velocity Impact

Polish Maritime Research ◽

10.2478/pomr-2021-0006 ◽

2021 ◽

Vol 28 (1) ◽

pp. 59-71

Author(s):

Zhaoyi Zhu ◽

Xiaowen Li ◽

Qinglin Chen ◽

Yingqiang Cai ◽

Yunfeng Xiong

Keyword(s):

Composite Laminates ◽

Impact Force ◽

Low Velocity Impact ◽

Back Side ◽

Low Velocity ◽

Velocity Impact ◽

Damage Area ◽

Impact Performance ◽

Composite Ship ◽

The Impact

Abstract Due to their excellent performance, composite materials are increasingly used in the marine field. It is of great importance to study the low-velocity impact performance of composite laminates to ensure the operational safety of composite ship structures. Herein, low-velocity drop-weight impact tests were carried out on 12 types of GRP laminates with different layup forms. The impact-induced mechanical response characteristics of the GRP laminates were obtained. Based on the damage model and stiffness degradation criterion of the composite laminates, a low-velocity impact simulation model was proposed by writing a VUMAT subroutine and using the 3D Hashin failure criterion and the cohesive zone model. The fibre failure, matrix failure and interlaminar failure of the composite structures could be determined by this model. The predicted mechanical behaviours of the composite laminates with different layup forms were verified through comparisons with the impact test results, which revealed that the simulation model can well characterise the low-velocity impact process of the composite laminates. According to the damage morphologies of the impact and back sides, the influence of the different layup forms on the low-velocity impact damage of the GRP laminates was summarised. The layup form had great effects on the damage of the composite laminates. Especially, the outer 2‒3 layers play a major role in the damage of the impact and the back side. For the same impact energy, the damage areas are larger for the back side than for the impact side, and there is a corresponding layup form to minimise the damage area. Through analyses of the time response relationships of impact force, impactor displacement, rebound velocity and absorbed energy, a better layup form of GRP laminates was obtained. Among the 12 plates, the maximum impact force, absorbed energy and damage area of the plate P4 are the smallest, and it has better impact resistance than the others, and can be more in line with the requirements of composite ships. It is beneficial to study the low-velocity impact performance of composite ship structures.

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Impact of Building Design Parameters on Daylighting Metrics Using an Analysis, Prediction, and Optimization Approach Based on Statistical Learning Technique

Sustainability ◽

10.3390/su11051474 ◽

2019 ◽

Vol 11 (5) ◽

pp. 1474 ◽

Cited By ~ 5

Author(s):

Jaewook Lee ◽

Mohamed Boubekri ◽

Feng Liang

Keyword(s):

Statistical Learning ◽

Building Design ◽

Design Parameters ◽

Optimization Approach ◽

Impact Performance ◽

Design Variables ◽

Design Attributes ◽

Learning Technique ◽

The Impact ◽

The Relationship

Daylighting metrics are used to predict the daylight availability within a building and assess the performance of a fenestration solution. In this process, building design parameters are inseparable from these metrics; therefore, we need to know which parameters are truly important and how they impact performance. The purpose of this study is to explore the relationship between building design attributes and existing daylighting metrics based on a new methodology we are proposing. This methodology involves statistical learning. It is an emerging methodology that helps us to analyze a large quantity of output data and the impact of a large number of design variables. In particular, we can use these statistical methodologies to analyze which features are important, which ones are not, and the type of relationships they have. Using these techniques, statistical models may be created to predict daylighting metric values for different building types and design solutions. In this article we will outline how this methodology works, and analyze the building design features that have the strongest impact on daylighting performance.

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Investigation on Impact Performance of Light-Weight Composite Honeycomb Sandwich Panels

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.249-250.949 ◽

2012 ◽

Vol 249-250 ◽

pp. 949-953

Author(s):

Iwakawa Yutaka ◽

Takahisa Machida ◽

Mitsuo Kobayashi ◽

Jian Mei He

Keyword(s):

Sandwich Composite ◽

Foil Thickness ◽

Design Parameters ◽

Light Weight ◽

Impact Performance ◽

Honeycomb Sandwich ◽

Honeycomb Sandwich Composite ◽

The Impact ◽

Analytical Approaches ◽

The Relationship

In this study, the relationship between the impact performances of light-weight honeycomb sandwich composite panels with design parameters like panel cores and face’s thicknesses and materials, honeycomb foil thickness and cell size etc. are experimentally evaluated through the spindle falling tests. Analytical approaches are also carried out to confirm the validity of the experiments based on 3D modeling and using ANSYS LS-DYNA software. Comparisons of the experimental and analytical results are reported in this study.

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Force attenuation capacity of weft-knitted spacer fabric in low-velocity impact

International Journal of Clothing Science and Technology ◽

10.1108/ijcst-06-2020-0100 ◽

2021 ◽

Vol ahead-of-print (ahead-of-print) ◽

Author(s):

Ryan Rudy ◽

Wiah Wardiningsih

Keyword(s):

Impact Force ◽

Test Method ◽

Low Velocity Impact ◽

Low Velocity ◽

Content Type ◽

Impact Performance ◽

Spacer Fabric ◽

Spacer Fabrics ◽

The Impact ◽

Peak Impact Force

PurposeThis study aimed to determine the peak impact force and force attenuation capacity of weft-knitted spacer fabrics intended for padding that can be used for human body protection against impact.Design/methodology/approachA total of five weft-knitted spacer fabrics were fabricated with four different diameters of nylon monofilament yarns and one doubled monofilament yarns, respectively. The impact performances of the weft-knitted spacer fabrics were tested using a drop test method with a customized test rig to simulate falling. Impact tests were conducted on single- and multilayered experimental spacer fabrics to investigate the peak impact force and force attenuation capacity.FindingsIt was found that weft-knitted spacer fabric with a coarser or larger diameter of monofilament spacer yarn generated lower impact force and higher force attenuation capacity, thus resulting in better impact performance. Greater force attenuation can be achieved by utilizing a higher number of spacer fabric layers. However, the increase in thickness must be considered with the spacer fabric end use.Originality/valueThis study employed relatively coarse nylon monofilament yarn as spacer yarns to gain knowledge on the impact performance of weft-knitted spacer fabrics compared to warp-knitted spacer fabrics which are more common. The results showed that the diameter of spacer yarn significantly influenced the impact performance of the experimental weft-knitted spacer fabrics. These results could be useful for designing and engineering textile-based impact protectors.

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Experimental Study on the Performance of a Crashworthy Device for the Monopile Offshore Wind Turbine against Ship Impact

Energies ◽

10.3390/en11113173 ◽

2018 ◽

Vol 11 (11) ◽

pp. 3173

Author(s):

Nianxin Ren ◽

Wei Li ◽

Zhe Ma ◽

Jinping Ou ◽

Dezhi Ning

Keyword(s):

Wind Turbine ◽

Impact Force ◽

Offshore Wind ◽

Design Parameters ◽

Steel Shell ◽

Offshore Wind Turbine ◽

Test Model ◽

Motion Platform ◽

Thin Steel ◽

The Impact

In the present work, a crashworthy device for a monopile offshore wind turbine has been proposed, which consists of the inner two-layer rubber torus and the outer thin steel shell. The performance of the crashworthy device against ship impact has been investigated experimentally. Based on the prototype of a 4 MW monopile wind turbine in the East China Sea, the scale ratio of the test model has been designed to be 1/50. The test ship model has been simplified as a “rigid car” equipped with a high-frequency force sensor in the front, which is available for changing the ship mass with different weights. The ship-impact velocity can be accurately controlled by a motion platform driven by a direct current machine. The effect of the key design parameters of the crashworthy device on its anti-impact performance has been tested and compared under typical ship impact cases. The results indicate that the crashworthy device can effectively reduce both the ship impact force and the top nacelle acceleration, and the physical mechanism that has been clarified. The outer thin steel shell can significantly use its structural deformation to absorb the ship impact energy, which is beneficial for reducing the structural damage of the offshore wind turbine (OWT)’s tower. The inner rubber torus can effectively prolong the ship impact duration, which is available for smoothing the impact force. Finally, the porous design for the outer steel shell of the crashworthy device has been proposed and tested.

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Study on the Influence of Closed-Cell Aluminum Foam on the Impact Performance of Concrete Pier after Equal Replacement with Stainless Steel Reinforcement

Advances in Materials Science and Engineering ◽

10.1155/2020/8356319 ◽

2020 ◽

Vol 2020 ◽

pp. 1-17

Author(s):

Xiwu Zhou ◽

Honglong Zhang ◽

Wenchao Zhang ◽

Guoxue Zhang

Keyword(s):

Stainless Steel ◽

Aluminum Foam ◽

Impact Test ◽

Impact Force ◽

Steel Reinforcement ◽

Change Rate ◽

Damage Rate ◽

Closed Cell ◽

Ultrasonic Damage ◽

The Impact

In this study, the impact test of two groups of reinforced concrete piers protected by closed-cell aluminum foam is carried out by using the ultrahigh drop hammer impact test system. The purpose of this study is to explore the impact resistance and protective performance of closed-cell aluminum foam under the impact load on the concrete bridge pier after replacing the ordinary reinforcement with stainless steel reinforcement. The study results show that the impact force is related to the overall stiffness of the specimen, as well as to the failure mode. When the impact velocity is less than 1.42 m/s, the closed-cell aluminum foam is in an elastic or yielding stage. The change rate of impact force (231 and 97.5, respectively), tip displacement (33.5 and 18, respectively), and ultrasonic damage rate of the concrete in the two groups of specimen is relatively small, while the change rate of the two groups of specimen remains approximately consistent. In addition, when the impact is greater than 1.42 m/s and the closed-cell aluminum foam is in the densification stage, the change rate of the impact force (increase from 231 to 819 and from 97.5 to 984.5), the tip displacement (increase from 33.5 to 67 and from 18 to 62), and ultrasonic damage rate of concrete are larger, which results in an increase in the dynamic response of the structure.

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Experimental Study on the Impact Resistance of Closed-Cell Aluminum Foam Protective Materials to RC Piers under Lateral Impact

Advances in Materials Science and Engineering ◽

10.1155/2021/9594496 ◽

2021 ◽

Vol 2021 ◽

pp. 1-18

Author(s):

Xiwu Zhou ◽

Wen Zhang ◽

Xiangyu Wang ◽

Wenchao Zhang ◽

Meng Zhan

Keyword(s):

Impact Energy ◽

Aluminum Foam ◽

Impact Force ◽

Experimental Testing ◽

Test System ◽

Protective Effects ◽

Lateral Impact ◽

Cumulative Impact ◽

Closed Cell ◽

The Impact

In this study, the lateral impact tests of six RC piers which were protected by closed-cell aluminum foam (CCAF) were carried out by making use of an ultrahigh drop hammer horizontal impact test system. The protective effects of CCAF with different densities on the piers were then analyzed. The data regarding the piers’ impact force, displacement, reinforcement strain, and crack and damage development were mainly collected during the experimental testing processes. The results indicated that, when the impact energy was less than 7258 J and the density of the CCAF was 0.45 g/cm3, the cumulative impact force and displacements of the piers decreased by 67% and 35%, respectively. Therefore, it was considered that the CCAF with a density of 0.45 g/cm3 had displayed the best protective effects at that stage. It was also observed that when the impact energy was greater than 7258 J and the density of the CCAF was 0.55 g/cm3, the cumulative impact force and displacements of the piers decreased by 25% and 18%, respectively. Therefore, the CCAF with a density of 0.55 g/cm3 had displayed the best protective effects at that stage. Furthermore, under the conditions of constant accumulative impact energy, the protective effects of CCAF on the piers were observed to be weakened if it entered the densification stage too early and high-yield platforms were formed due to the density levels becoming too high. However, it was found that reasonable density and thickness increases could effectively delay the entry of CCAF into the densification stage, which effectively reduced the shearing effects which occurred when the impact speeds were too high, thereby preventing the shear failure of the piers.

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Scale Effect on Impact Performance of Unidirectional Glass Fiber Reinforced Epoxy Composite Laminates

Materials ◽

10.3390/ma12081319 ◽

2019 ◽

Vol 12 (8) ◽

pp. 1319

Author(s):

Yiou Shen ◽

Bing Jiang ◽

Yan Li

Keyword(s):

Glass Fiber ◽

Energy Absorption ◽

Scale Effect ◽

Impact Force ◽

Impact Response ◽

Fiber Reinforced ◽

Impact Performance ◽

Glass Fiber Reinforced ◽

Wide Range ◽

The Impact

As a result of the increasing use of glass fiber reinforced plastic (GFRP) composites in engineering fields, the investigation of scale effect on impact performance for this kind of composite is essential for large scale structure design. The effects of scaling on the impact response of simply supported unidirectional GFRP were investigated through drop weight impact (DWI) tests in this study. Impact tests were undertaken over a wide range of energies to generate damages between barely visible and initiated penetration on four scale size GFRP laminates. The main impact responses including impact force, contact duration, displacement, energy absorption and damage area of scaled specimens were normalized to compare with the full-size specimen. It was found that the impact response of large sample with elastic deformation and small area of delamination can be predicted accurately according to a geometrical similar scaling law. Scale effect was found in the damage threshold force and absorbed energy of the laminates when significant internal damage occurs due to the microstructural effect becoming important in resisting impact force and absorbing impact energy. Moreover, the energy partition and effective stiffness were calculated according to the energy balance model to reveal the contribution of different modes of deformations on energy absorption for the GFRP laminates.

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