scholarly journals Impact Force Identification of the Variable Pressure Flexible Impact End-Effector in Space Debris Active Detumbling

2020 ◽  
Vol 10 (9) ◽  
pp. 3011
Author(s):  
Ziying Wei ◽  
Huibo Zhang ◽  
Baoshan Zhao ◽  
Xiaoang Liu ◽  
Rui Ma
Keyword(s):  
Space Debris ◽  
Impact Force ◽  
Pressure Change ◽  
Friction Model ◽  
Space Environment ◽  
Variable Pressure ◽  
Force Model ◽  
End Effector ◽  
Identification Error ◽  
The Impact

The security of the space environment is under serious threat due to the increase in space debris in orbit. The active removal of space debris could ensure the sustainable use of the space environment; this removal relies on detumbling technology. According to the characteristics of the mechanical impact-type active detumbling method, this paper discusses a method to accurately identify the impact force using a pressure sensor. In this work, the impact force between a flexible impact end-effector and the space debris was analyzed theoretically and experimentally considering the pressure change during impact. Firstly, a nonlinear impact force model was established for the impact between a flexible end-effector and space debris. Secondly, impact experiments were performed and the friction model was modified. Finally, the effect of detumbling was verified through simulation experiments. The results showed that the identification error of normal impact force was less than 6.7% and the identification error of tangential friction force was less than 6.9%. Therefore, this identification method of impact force met the requirements of space debris detumbling, which has important guiding significance for the active removal technology of space debris.

Debris/Micrometeoroid Impacts and Synergistic Effects on Spacecraft Materials

MRS Bulletin ◽  
2010 ◽  
Vol 35 (1) ◽  
pp. 41-47 ◽  
Author(s):  
E. Grossman ◽  
I. Gouzman ◽  
R. Verker
Keyword(s):  
Space Debris ◽  
Synergistic Effects ◽  
Degradation Mechanism ◽  
Space Environment ◽  
Materials Properties ◽  
Gas Gun ◽  
Naturally Occurring ◽  
Space Activity ◽  
The Impact ◽  
Debris Impact

AbstractIn the last 40 years, the increased space activity created a new form of space environment of hypervelocity objects—space debris—that have no functional use. The space debris, together with naturally occurring ultrahigh velocity meteoroids, presents a significant hazard to spacecraft. Collision with space debris or meteoroids might result in disfunction of external units such as solar cells, affecting materials properties, contaminating optical devices, or destroying satellites. The collision normally results in the formation of additional debris, increasing the hazard for future missions. The hypervelocity debris effect is studied by retrieving materials from space or by using ground simulation facilities. Simulation facilities, which include the light gas gun and Laser Driven Flyer methods, are used for studying the materials degradation due to debris impact. The impact effect could be accelerated when occurring simultaneously with other space environment components, such as atomic oxygen, ultraviolet, or x-ray radiation. Understanding the degradation mechanism might help in developing materials that will withstand the increasing hazard from the space debris, allowing for longer space missions. The large increase in space debris population and the associated risk to space activity requires significant measures to mitigate this hazard. Most current efforts are being devoted to prevention of collisions by keeping track of the larger debris and avoiding formation of new debris.

An experimental and simulation study of the flow pattern characteristics of water jet impingements in boreholes

2021 ◽  
pp. 014459872110520
Author(s):  
Yabin Gao ◽  
Xin Xiang ◽  
Ziwen Li ◽  
Xiaoya Guo ◽  
Peizhuang Han
Keyword(s):  
High Speed ◽  
Impact Force ◽  
Jet Impingement ◽  
Flow Patterns ◽  
Water Jet ◽  
Solid Boundary ◽  
Force Model ◽  
Water Jets ◽  
Contact Surfaces ◽  
The Impact

Hydraulic slotting has become one of the most common technologies adopted to increase permeability in low permeability in coal field seams. There are many factors affecting the rock breaking effects of water jets, among which the impact force cannot be ignored. To study the influencing effects of contact surface shapes on jet flow patterns and impact force, this study carried out experiments involving water jet impingement planes and boreholes under different pressure conditions. The investigations included numerical simulations under solid boundary based on gas–liquid coupling models and indoor experiments under high-speed camera observations. The results indicated that when the water jets impinged on different contact surfaces, obvious reflection flow occurred, and the axial velocity had changed through three stages during the development process. Moreover, the shapes of the contact surfaces, along with the outlet pressure, were found to have impacts on the angles and velocities of the reflected flow. The relevant empirical formulas were summarized according to this study's simulation results. In addition, the flow patterns and shapes of the contact surfaces were observed to have influencing effects on the impact force. An impact force model was established in this study based on the empirical formula, and the model was verified using both the simulation and experimental results. It was confirmed that the proposed model could provide important references for the optimization of the technical parameters water jet systems, which could provide theoretical support for the further intelligent and efficient transformation of coal mine drilling water jet technology.

scholarly journals Effective Formula for Impact Damping Ratio for Simulation of Earthquake-induced Structural Pounding

Geosciences ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 347 ◽  
Author(s):  
Seyed Mohammad Khatami ◽  
Hosein Naderpour ◽  
Rui Carneiro Barros ◽  
Anna Jakubczyk-Gałczyńska ◽  
Robert Jankowski
Keyword(s):  
Kinetic Energy ◽  
Impact Force ◽  
Damping Ratio ◽  
Dissipated Energy ◽  
Force Model ◽  
Single Collision ◽  
Structural Pounding ◽  
Impact Forces ◽  
The Impact ◽  
Impact Damping

Structural pounding during earthquakes may cause substantial damage to colliding structures. The phenomenon is numerically studied using different models of collisions. The aim of the present paper is to propose an effective formula for the impact damping ratio, as a parameter of the impact force model used to study different problems of structural pounding under seismic excitations. Its accuracy has been verified by four various approaches. Firstly, for the case of collisions between two structural elements, the dissipated energy during impact has been compared to the loss of kinetic energy. In the second stage of verifications, the peak impact forces during single collision have been analyzed. Then, the accuracy of different equations have been verified by comparing the impact force time histories for the situation when a concrete ball is dropped on a rigid concrete surface. Finally, pounding between two structures during earthquakes has been studied. The results of the analysis focused on comparison between dissipated and kinetic energy show relatively low errors between calculated and assumed values of the coefficient of restitution when the proposed equation is used. In addition, the results of the comparison between experimentally and numerically determined peak impact forces during single collision confirm the effectiveness of the approach. The same conclusion has been obtained for the whole impact time history for collision between a ball and a rigid surface. Finally, the results of the comparative analysis, conducted for pounding between two structures during an earthquake, confirm the simulation accuracy when the proposed approach is used. The above conclusions indicate that the proposed formula for impact damping ratio, as a parameter of impact force model for simulation of earthquake-induced structural pounding, is very effective and accurate in numerical simulations in the case of different scenarios.

scholarly journals Cobot with Prismatic Compliant Joint Intended for Doppler Sonography

Robotics ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 14 ◽  
Author(s):  
Juan Sandoval ◽  
Med Amine Laribi ◽  
Saïd Zeghloul ◽  
Marc Arsicault ◽  
Jean-Michel Guilhem
Keyword(s):  
Musculoskeletal Disorder ◽  
Doppler Sonography ◽  
Impact Force ◽  
Variable Stiffness ◽  
Safety Performance ◽  
End Effector ◽  
Force Criterion ◽  
Compliant Joint ◽  
The Impact ◽  
Collaborative Robot

This paper deals with a collaborative robot, i.e., cobot, coupled with a new prismatic compliant joint (PCJ) at its end-effector. The proposed collaborative solution is intended for Doppler sonography to prevent musculoskeletal disorders issues. On one hand, the Doppler sonographer’s postures are investigated based on motion capture use during the arteries examination. This study highlighted that configurations adopted by angiologists lead to the musculoskeletal disorder. On the other hand, the proposed PCJ with variable stiffness gives an intrinsic compliance to the cobot handling the probe. This feature allows preserving the human safety when both human and cobot share a common workspace. The effectiveness of the proposed solution is experimentally validated through a 7-DoF Franka Emika robot virtually coupled with the PCJ, during the execution of a trajectory performed during a Doppler ultrasound exam. The impact force criterion is considered as a safety performance.

scholarly journals A new impact dynamics model of a clearance joint considering the adhesive effects in space environment

2020 ◽  
Vol 306 ◽  
pp. 01005
Author(s):  
Ruiting Tong ◽  
Zefen Quan ◽  
Qi Wan ◽  
Xiaojun Fu ◽  
Geng Liu
Keyword(s):  
Hybrid Model ◽  
Contact Process ◽  
Contact Forces ◽  
Space Environment ◽  
Impact Dynamics ◽  
Force Model ◽  
Dynamics Model ◽  
Clearance Joint ◽  
The Impact ◽  
Adhesive Forces

In space environment, there is severe adhesive effect, and the impact contact process shows different phenomenon due to the adhesive forces. In this paper, a new impact dynamics model of a clearance joint is developed considering the adhesive effects. The Hertz contact model, L-J potential and Dugdale model are combined, and an adhesive force term is included in the original hybrid contact force model. Taking a clearance joint as an example, the theory of adhesive forces during the impact contact process is given, and the influence of the adhesive forces is investigated. Negative forces are discovered at the beginning of the contact, and the contact forces of the modified model are higher than the hybrid model. Besides, the indentation depth is also higher than the hybrid model. The energy conservation principle is employed to explain the phenomena, and the contact forces will be underestimated if the adhesive effects are ignored. This work could be contributed to estimating the contact forces and friction forces more reasonablely in the space environment.

scholarly journals Dynamic characteristics of mistuned bladed disk system under rub-impact force

2020 ◽  
Vol 12 (11) ◽  
pp. 168781402097306
Author(s):  
Hui Zhang ◽  
Tianyu Zhao ◽  
Hongyuan Zhang ◽  
Honggang Pan ◽  
Huiqun Yuan
Keyword(s):  
Finite Element ◽  
Variable Thickness ◽  
Impact Force ◽  
Element Model ◽  
Force Model ◽  
Disk System ◽  
Element Analysis ◽  
Bladed Disk ◽  
Blade Tip ◽  
The Impact

In order to study the rubbing of the mistuned bladed disk system with variable thickness blades, an elastically supported shaft-variable thickness blades coupled finite element model is established in this paper. A new rubbing force model is proposed considering the variable thickness section characteristics and rotation effect of the variable thickness blade. A method of mistuned parameter identification is introduced which consists of static frequency testing of blades, dichotomy, and finite element analysis. Based on the finite element method, the mistuned bladed disk system is made dynamic analysis in full rubbing by applying the judgment load method. The dynamic response of the mistuned bladed disk system is discussed under different conditions. The results show that increasing the amount of mistuning will increase the system vibration. At high speeds, the impact force will be partially offset by centrifugal force. And the rubbing gap affects the form of rubbing. With the gap decreases, the system will change from intermittent rubbing to continuous rubbing. In addition, when the system is rubbed, due to energy dissipation and blade damping, the stress is transferred from the blade tip to the blade root and attenuated. In general, rubbing is a random complex nonlinear vibration process.

scholarly journals Modeling and analysis of impact based on numerical and experimental approaches

2018 ◽  
Vol 10 (12) ◽  
pp. 168781401881306
Author(s):  
Xupeng Wang ◽  
Yan Zhang ◽  
Zhu Gao ◽  
Xiaomin Ji ◽  
Lin Li
Keyword(s):  
Mechanical System ◽  
Contact Force ◽  
Impact Force ◽  
Numerical Results ◽  
Experimental Results ◽  
Force Model ◽  
Restitution Coefficient ◽  
Contact Force Model ◽  
Improved Model ◽  
The Impact

Impact is a universal phenomenon and has serious influences on the dynamic characteristics of mechanical system, so it is critical to accurately describe the effects of impact. In this work, a numerical and comprehensive method is presented to calculate the impact force in clearance joint during impact process, which has higher effectiveness and accuracy than the most popular used L-N model. Different from traditional contact models, where the coefficient of restitution is assumed to be a constant value nearly to 1 during impact process, the improved model in this work sets up the model of restitution coefficient related to two important parameters for impact phenomenon, which are initial impact velocity and the yield strength of the materials in clearance joints. A great number of numerical and experimental results are introduced and compared to validate the improved contact force model; it needs to be highlighted that the numerical results are based on the improved model and the most popular impact force model presented by Lankarani and Nikravesh, and the experimental results are based on two typical pendulum experimental test rigs. It can be concluded that (1) when compared to the experimental results, the numerical results based on the improved model are in better agreement than those based on Lankarani and Nikravesh impact force model; (2) the numerical results based on the improved model are in reasonable agreement with the experimental results, and the relative errors of impact force and restitution coefficient are all no more than 10% between numerical and experimental results; and (3) the improved contact force model is effective and can exactly describe the impact effects between two bodies in mechanical system.

scholarly journals Research on building the formula to determine the rate of penetration for polycrystalline diamond compact bits

2021 ◽  
Vol 62 (3a) ◽  
pp. 57-64
Author(s):  
Tu Van Truong ◽  
Hung Tien Nguyen ◽  
Duong Hong Vu ◽  
Keyword(s):  
Impact Force ◽  
Polycrystalline Diamond ◽  
Oil Field ◽  
Force Model ◽  
Rock Destruction ◽  
Rate Of Penetration ◽  
Pdc Bit ◽  
Polycrystalline Diamond Compact ◽  
The Impact ◽  
Penetration Parameter

Nowadays, polycrystalline diamond compact (PDC) drill bits are widely used in the oil and gas industry when drilling in soft rocks. However, parameters used for the PDC bit are usually based on the instructions of the drill manufacturer with a very wide adjustment range. Therefore, it is necessary to have a specific formula in order to determine the rate of penetration parameter (ROP) for the PDC bit in evaluating the influence of the parameters, rock mechanical properties and other parameters on the rate of penetration parameter (ROP). From there, it gives reasonable parameters and improves the design of the PDC bit to improve drilling efficiency. The article applies theoretical analysis method and Dalamber's principle to illuminate and build up the impact force model for PDC bits in the rock destruction process. From the impact force model, a formula to determine ROP for PDC bits was proposed. Finally, the authors applied the research results to the actual data obtained from the Nam Rong - Doi Moi oil field. The formula for determining the rate of penetration parameter (ROP) for the PDC bit that the authors have built has high accuracy and can be applied to many different rock.

scholarly journals The Interaction between the LEO Satellite Constellation and the Space Debris Environment

2021 ◽  
Vol 11 (20) ◽  
pp. 9490
Author(s):  
Shuyi Ren ◽  
Xiaohua Yang ◽  
Ronglan Wang ◽  
Siqing Liu ◽  
Xiaojing Sun
Keyword(s):  
Growth Rate ◽  
Success Rate ◽  
Space Debris ◽  
Low Earth Orbit ◽  
Space Environment ◽  
Risk Level ◽  
Collision Risk ◽  
Orbital Parameters ◽  
Space Objects ◽  
The Impact

The wide application of satellite constellations in the field of space-based global communications and remote sensing has led to a substantial increase in small-satellite launch plans, a sharp increase in the density of space objects in low-Earth orbit (LEO), and a reduction in available orbit and frequency resources. This will further aggravate the trend of deterioration of the space debris environment. Taking the Starlink constellation as an example, this paper describes the influence of the constellation from the environmental debris flux of the satellite, the evaluation of the number of evasion maneuvers, the change of risk level, the success rate of post mission disposal (PMD) and the growth rate of space objects. The simulation results show that the collision risk of the Starlink constellation is related to the orbital parameters, and the higher success rate of post-mission disposal (PMD) can reduce the collision risk of the constellation. The large constellations increases the growth rate of space objects, and even if all the satellites are disposed of after the mission, the impact of constellations on the space environment can not be offset.

Numerical modeling and experimental study on a novel pounding tuned mass damper

2017 ◽  
Vol 24 (17) ◽  
pp. 4023-4036 ◽  
Author(s):  
Wenxi Wang ◽  
Xugang Hua ◽  
Xiuyong Wang ◽  
Zhengqing Chen ◽  
Gangbing Song
Keyword(s):  
Experimental Study ◽  
Impact Force ◽  
Damping Ratio ◽  
Tuned Mass Damper ◽  
Frame Structure ◽  
Force Model ◽  
Control Performance ◽  
Viscoelastic Materials ◽  
Mass Damper ◽  
The Impact

Owing to its easy implementation and robustness, the pounding tuned mass damper (PTMD), which uses viscoelastic materials to cover the pounding boundary to increase the energy dissipation during impact, has been studied in recent years. The conventional PTMD design includes a gap between the pounding mass and the viscoelastic material; the value of this gap should be optimized. In this paper, a novel PTMD is proposed to control structural vibrations. In the proposed PTMD, the pounding boundary covered by viscoelastic materials is simply added to one side of the tuned mass when the tuned mass is in the equilibrium position. Unlike the conventional PTMD, the gap between the tuned mass and the pounding boundary is zero in the proposed design and is no longer a design parameter. A new analytic model is proposed to accurately predict the impact force between viscoelastic materials and steel. Through comparison with the impact force and the indentation from impact experiments, the accuracy of the proposed impact force model is validated. To verify the control performance of the proposed PTMD, an experimental study on a frame with the proposed PTMD is carried out to investigate the control performance in free vibration and forced vibration cases. Both experimental and numerical results show that the proposed PTMD can effectively reduce the response of the frame structure and that the damping ratio of the frame is significantly increased.

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