Transient contact-impact behavior for passive walking of compliant bipedal robots

2021 ◽  
Vol 42 ◽  
pp. 101076
Author(s):  
Yunian Shen ◽  
Ye Kuang
Keyword(s):  
Impact Behavior ◽  
Bipedal Robots ◽  
Passive Walking ◽  
Transient Contact ◽  
Contact Impact

Modeling and Simulation of Clamp Band Dynamic Envelope in a LV/SC Separation System

2011 ◽  
Vol 141 ◽  
pp. 359-363 ◽  
Author(s):  
Jun Lan Li ◽  
Shao Ze Yan ◽  
Xue Feng Tan
Keyword(s):  
Friction Coefficient ◽  
Modeling And Simulation ◽  
Band System ◽  
Separation Process ◽  
Impact Behavior ◽  
Separation System ◽  
Lumped Mass ◽  
Lumped Mass Method ◽  
Simulation Results ◽  
Contact Impact

The clamp band system is a typical locked and separated device of the launch vehicle (LV) / the spacecraft (SC), and its release-separation process is one of the important factors that affect the LV/SC separation movement. A nonlinear spring-damper model was employed to describe the contact-impact behavior between the V-segment of the clamp band and the LV/SC interface, and lumped mass method was used to depict the clamp band. By using ADAMS, a dynamic model of the clamp band system was established. The simulation results show that the impulse of the explosive bolts and the stiffness of lateral-restraining springs have significant effects on the clamp band dynamic envelope. The shock of the satellite-vehicle separation is very vulnerable to the clamp band pretension and the friction coefficient between the V-segment and the LV/SC interface.

scholarly journals Study on Transient Contact-Impact Characteristics and Driving Capability of Piezoelectric Stack Actuator

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 233
Author(s):  
Yanze Li ◽  
Yunian Shen ◽  
Qiaoping Xing
Keyword(s):  
High Speed ◽  
Laser Doppler Vibrometer ◽  
Contact Forces ◽  
Driving Voltage ◽  
Lagrange Equations ◽  
Transient Responses ◽  
Transient Contact ◽  
Contact Impact ◽  
Piezoelectric Stack Actuator ◽  
Driving Capability

The transient contact-impact mechanism and driving capability of the piezoelectric stack actuator is analyzed using both experimental and theoretical methods. An experimental setup and its corresponding measurement approaches for the transient responses are designed. The launch range of the object resulting from the first contact-impact is measured through laser doppler vibrometer and the motion process is captured by high-speed camera. Experimental results illustrate that the launch range increases firstly and decreases subsequently as the frequency of the sine driving voltage increases. Meanwhile, considering the local viscoelastic contact deformation, a theoretical methodology including the mechanics model for the driving process is proposed. Based on the Lagrange equations of second kind, the governing equation of the driving system is derived. Transient responses are calculated using the fourth-order Runge–Kutta integration method. Contact forces and Poisson’s coefficient of restitution are calculated by the proposed theoretical method. The results of launch range show that the theoretical solutions have a good agreement with the experimental data. The peak value of contact force increases firstly and decreases subsequently with the increase of voltage frequency. In addition, the coefficient of restitutions is roughly 0.9 when f is greater than 3.5 kHz.

Experimental and theoretical analyses of the contact-impact behavior of Babbitt ZChSnSb11-6

2017 ◽  
Vol 233 (7) ◽  
pp. 1267-1276 ◽  
Author(s):  
Yao Wang ◽  
Shujun Li ◽  
Dan Xiang ◽  
Wenjun Meng
Keyword(s):  
Contact Force ◽  
Numerical Solutions ◽  
Permanent Deformation ◽  
Absolute Error ◽  
Coefficient Of Restitution ◽  
Experimental Results ◽  
Impact Behavior ◽  
Impact Model ◽  
Oil Film ◽  
Contact Impact

Contact-impact between Babbitt and steel surfaces is an ubiquitous phenomenon during the operation of oil-film bearing. To study this phenomenon, a contact-impact method of Babbitt ZChSnSb11-6 was designed and the contact-impact test was performed. For the purpose of getting a more complete understanding of the contact-impact mechanical properties of Babbitt ZChSnSb11-6, the relationships of coefficient of restitution, permanent deformation, and drop height (i.e. the initial impact velocity) were analyzed; and, the constitutive behavior between the contact force and the contact deflection was studied. Then, based on the empirical formulation developed by Brake, an indentation contact-impact model during impact events was established, which theoretically explained the contact-impact behavior of Babbitt ZChSnSb11-6. Meanwhile, the experimental results were compared with the numerical solutions solved by using MATLAB. Results revealed the established model shows a good agreement with the experimental results. The mean absolute error of coefficient of restitution was less than 0.025, and the difference for the permanent deformation after impact was less than 1%. For the contact-impact tests with different size parameters, the length and the diameter of 20 steel rods were the two significant influencing factors on the permanent deformation and coefficient of restitution of Babbitt flat surface; and, the relationship of contact force and contact deflection appeared to display the similar trend. It was concluded that the established contact-impact model has the effectiveness and applicablility on describing its contact-impact behaviors, and which can provide theoretical and experimental supports for the prediction of contact deflection and contact force of the Babbitt ZChSnSb11-6 of oil-film bearing.

Beam-to-Beam Impact Behavior of Reinforced Concrete Frames under Severe Ground Motions

2011 ◽  
Vol 243-249 ◽  
pp. 1210-1218
Author(s):  
Guo Hui Huang ◽  
Zheng He
Keyword(s):  
Reinforced Concrete ◽  
Progressive Collapse ◽  
Ground Motions ◽  
Impact Behavior ◽  
Concrete Frames ◽  
Reinforced Concrete Frame ◽  
Concrete Frame ◽  
Contact Impact ◽  
Reinforced Concrete Frame Structures ◽  
The Impact

The beam-to-beam impact behavior during the progressive collapse progress of reinforced concrete frame structures under severe ground motions is studied in which three types of impact are included, i.e. 1) contact-impact between one-end failed active beam and intact passive beam; 2) contact-impact between two-end failed active beam and intact passive beam, and 3) contact-impact of one-end failed active beam and one-end failed passive beam. As the first step, the initial impact conditions are established based on the principles of the kinematics and the structural dynamics. Then, the velocities of the beams at the impact instant and the locations of the impact would occur are derived. A so-called impact mass factor is introduced in the paper and determined through the principle of equivalent energy. The history of contact force between the beams involved in the impact is evaluated by the Hertz-damp model. The responses of the passive beam are calculated by solving the equation of motion of a generalized single degree of freedom system.

Simulation of hertz transient contact/impact of flexible bodies

2012 ◽  
Vol 23 (2) ◽  
pp. 225-232 ◽  
Author(s):  
Changgen Bu ◽  
Boru Xia ◽  
Yinjun Lian ◽  
Hui Zeng
Keyword(s):  
Flexible Bodies ◽  
Transient Contact ◽  
Contact Impact

Finite Element Analysis of Rotational Contact-Impact Behavior of a Geared Rotor System

1996 ◽  
Author(s):  
Makoto Tanabe ◽  
Chen Jie Jiang ◽  
Koya Takazawa
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Present Method ◽  
Rotor System ◽  
Impact Behavior ◽  
Experimental Result ◽  
Element Formulation ◽  
Element Analysis ◽  
Numerical Examples ◽  
Contact Impact

Abstract A simple and efficient finite element formulation and numerical method to solve it for the rotational contact-impact behavior of a geared rotor system are given. A gear element is devised to model the contact-impact behavior between gears in which the irregularity of tooth pitch is also considered. A computer program has been developed to solve this problem. Numerical examples of an electric disk grinder are demonstrated and compared with the experimental result to show the effectiveness of the present method.

scholarly journals Analytical Study of Babbitt/steel Composite Structural Bars in Oblique Contact-impact with a Solid Flat Surface

2019 ◽  
Vol 10 (1) ◽  
pp. 213-228 ◽  
Author(s):  
Yao Wang ◽  
Zhuang Fu
Keyword(s):  
Angular Velocity ◽  
Contact Force ◽  
Flat Surface ◽  
Permanent Deformation ◽  
Coefficient Of Restitution ◽  
Contact Forces ◽  
Experimental Results ◽  
Impact Behavior ◽  
Contact Impact ◽  
Weak Material

Abstract. The oblique contact-impact characteristic of the composite structural bar composed of Babbitt alloy and low-carbon steel (ZChSbSb11-6 ∕ AISI 1020) with a solid flat surface (AISI 1045) was studied theoretically and experimentally. The dynamic equation of the composite structural bar with vibration response during the contact-impact was established using the momentum theorem and assumed mode method, and the instantaneous contact forces during different impact phases were analyzed based on modified Jackson–Green model. Four sets of experiments (i.e. different proportion of Babbitt, ξ={1/8,1/2,3/4,7/8}) for the initial angle, θ=45∘, and different initial velocities were performed; and, the rebound linear and angular velocity of the contact point of composite structural bar after impact was calculated and compared with experimental results. Besides, the coefficient of restitution, the relation of contact force and contact deflection, and the permanent deformation were also compared for the composite structural bars with different proportions in combination, ξ. Three critical angles are found to determine whether the composite bar slides or not, but are prominently different for the composite bars with different ξ. In comparing with the experimental results, the numerical solutions of rebound linear and angular velocity had yield encourage results and, all relative errors were small, indicating that the simulations are in good agreement with the experimental results. Also, the oblique contact-impact behavior involving the coefficient of restitution, the relation of contact force and contact deflection, and the permanent deformation was explained in detail. It can be concluded that as the proportion of Babbitt ξ increases, the composite structural bar presents a characteristic of ease of deflection. And the contact-impact behavior of structural entity is closely related to the inherent properties of the elasto-plastic material, especially for the weak material of composite structures. The more easily the impacting object is deformed, the small the contact force during the contact-impact, which also indicates the yield strength of weak material is a very significant parameter in the event of collision. Such work could give conducive insights to contact-impact problems of the key parts or structures composed of composite materials in mechanical system.

Simulation and Visualization of Contact-Impact Behavior of Two Gears

2002 ◽  
Vol 2002.12 (0) ◽  
pp. 161-164
Author(s):  
Seiji KOMIYA ◽  
Makoto TANABE ◽  
Qiang GAO
Keyword(s):  
Impact Behavior ◽  
Contact Impact
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