Conditions for Dual Compression in Perfectly Elastic Three-Dimensional Collisions

1999 ◽  
Vol 66 (3) ◽  
pp. 607-611 ◽  
Author(s):  
J. A. Batlle
Keyword(s):  
Friction Coefficient ◽  
Multibody Systems ◽  
Single Point ◽  
Three Dimensional ◽  
Threshold Value ◽  
Restitution Coefficient ◽  
Compression Phase ◽  
Elastic Collisions ◽  
S Model

The jamb (self-locking) process in single-point three-dimensional rough collisions in multibody systems may lead to a dual compression: a second compression phase develops after an initial compression-expansion one. In such a case the usual energetical restitution coefficient ew is ill defined. This article presents a thorough analysis, by means of the incremental Routh ’s model, of the conditions leading to dual compression in the case of perfectly elastic collisions. For a given general collision configuration and for each value of the friction coefficient greater than the threshold value for jamb, there is always a domain of directions of the incident velocity leading to dual compression. An application example is presented.

scholarly journals Three-dimensional CFD modeling of thermal behavior of a disc brake and pad for an automobile

2020 ◽  
Vol 15 (4) ◽  
pp. 543-549
Author(s):  
Haydar Kepekci ◽  
Ergin Kosa ◽  
Cüneyt Ezgi ◽  
Ahmet Cihan
Keyword(s):  
Cast Iron ◽  
Friction Coefficient ◽  
Elevated Temperatures ◽  
Gray Cast Iron ◽  
Three Dimensional ◽  
Brake System ◽  
Gray Cast ◽  
Cfd Modeling ◽  
Disc Brake ◽  
Disc Material

Abstract The brake system of an automobile is composed of disc brake and pad which are co-working components in braking and accelerating. In the braking period, due to friction between the surface of the disc and pad, the thermal heat is generated. It should be avoided to reach elevated temperatures in disc and pad. It is focused on different disc materials that are gray cast iron and carbon ceramics, whereas pad is made up of a composite material. In this study, the CFD model of the brake system is analyzed to get a realistic approach in the amount of transferred heat. The amount of produced heat can be affected by some parameters such as velocity and friction coefficient. The results show that surface temperature for carbon-ceramic disc material can change between 290 and 650 K according to the friction coefficient and velocity in transient mode. Also, if the disc material gray cast iron is selected, it can change between 295 and 500 K. It is claimed that the amount of dissipated heat depends on the different heat transfer coefficient of gray cast iron and carbon ceramics.

scholarly journals Dynamic response analysis for multi-degrees-of-freedom parallel mechanisms with various types of three-dimensional clearance joints

2021 ◽  
Vol 18 (3) ◽  
pp. 172988142110177
Author(s):  
Jia Yonghao ◽  
Chen Xiulong
Keyword(s):  
Dynamic Response ◽  
Multibody Systems ◽  
Parallel Mechanism ◽  
Three Dimensional ◽  
Response Analysis ◽  
Parallel Mechanisms ◽  
Dynamics Model ◽  
Clearance Joints ◽  
Clearance Joint ◽  
Spatial Parallel Mechanism

For spatial multibody systems, the dynamic equations of multibody systems with compound clearance joints have a high level of nonlinearity. The coupling between different types of clearance joints may lead to abundant dynamic behavior. At present, the dynamic response analysis of the spatial parallel mechanism considering the three-dimensional (3D) compound clearance joint has not been reported. This work proposes a modeling method to investigate the influence of the 3D compound clearance joint on the dynamics characteristics of the spatial parallel mechanism. For this purpose, 3D kinematic models of spherical clearance joint and revolute joint with radial and axial clearances are derived. Contact force is described as normal contact and tangential friction and later introduced into the nonlinear dynamics model, which is established by the Lagrange multiplier technique and Jacobian of constraint matrix. The influences of compound clearance joint and initial misalignment of bearing axes on the system are analyzed. Furthermore, validation of dynamics model is evaluated by ADAMS and Newton–Euler method. This work provides an essential theoretical basis for studying the influences of 3D clearance joints on dynamic responses and nonlinear behavior of parallel mechanisms.

scholarly journals THRESHOLD VALUE OF THREE-DIMENSIONAL BOOTSTRAP PERCOLATION

2003 ◽  
Vol 14 (04) ◽  
pp. 529-536 ◽  
Author(s):  
DIRK KURTSIEFER
Keyword(s):  
Present Article ◽  
Three Dimensional ◽  
Threshold Value ◽  
Critical Value ◽  
Bootstrap Percolation ◽  
Infinite Lattice

The present article deals with the critical value pc of the three-dimensional bootstrap percolation. We will check the behavior of pc for different lengths of the lattice and additionally we will scale pc in the limit of an infinite lattice.

scholarly journals An Intramolecular Salt Bridge in Bacillus thuringiensis Cry4Ba Toxin Is Involved in the Stability of Helix α-3, Which Is Needed for Oligomerization and Insecticidal Activity

2017 ◽  
Vol 83 (20) ◽  
Author(s):  
Sabino Pacheco ◽  
Isabel Gómez ◽  
Jorge Sánchez ◽  
Blanca-Ines García-Gómez ◽  
Mario Soberón ◽  
...  
Keyword(s):  
Bacillus Thuringiensis ◽  
Double Point ◽  
Single Point ◽  
Three Dimensional ◽  
Point Mutations ◽  
Salt Bridge ◽  
Dimensional Structure ◽  
Cry Toxins ◽  
Content Type ◽  
Domain I

ABSTRACT Bacillus thuringiensis three-domain Cry toxins kill insects by forming pores in the apical membrane of larval midgut cells. Oligomerization of the toxin is an important step for pore formation. Domain I helix α-3 participates in toxin oligomerization. Here we identify an intramolecular salt bridge within helix α-3 of Cry4Ba (D111-K115) that is conserved in many members of the family of three-domain Cry toxins. Single point mutations such as D111K or K115D resulted in proteins severely affected in toxicity. These mutants were also altered in oligomerization, and the mutant K115D was more sensitive to protease digestion. The double point mutant with reversed charges, D111K-K115D, recovered both oligomerization and toxicity, suggesting that this salt bridge is highly important for conservation of the structure of helix α-3 and necessary to promote the correct oligomerization of the toxin. IMPORTANCE Domain I has been shown to be involved in oligomerization through helix α-3 in different Cry toxins, and mutations affecting oligomerization also elicit changes in toxicity. The three-dimensional structure of the Cry4Ba toxin reveals an intramolecular salt bridge in helix α-3 of domain I. Mutations that disrupt this salt bridge resulted in changes in Cry4Ba oligomerization and toxicity, while a double point reciprocal mutation that restored the salt bridge resulted in recovery of toxin oligomerization and toxicity. These data highlight the role of oligomer formation as a key step in Cry4Ba toxicity.

Resolving the Unique Invariant Slip-Direction in Rigid Three-Dimensional Multi-Point Impacts at Stick-Slip Transitions

2018 ◽  
Author(s):  
Abhishek Chatterjee ◽  
Alan Bowling
Keyword(s):  
Single Point ◽  
Three Dimensional ◽  
Impact Behavior ◽  
Slip Direction ◽  
Stick Slip ◽  
Impact Forces ◽  
Post Impact ◽  
Impact Problems ◽  
Slip Transition ◽  
The Impact

This work presents a new approach for resolving the unique invariant slip direction at Stick-Slip Transition during impact. The solution method presented in this work is applicable to both single-point and multi-point impact problems. The proposed method utilizes rigid body constraints to resolve the impact forces at all collision points in terms of a single independent impact forces parameter. This work also uses an energetic coefficient of restitution to terminate impact events, thereby yielding energetically consistent post-impact behavior.

Trajectory Tracking of Underactuated Multibody Systems

2011 ◽  
Author(s):  
Stefan Reichl ◽  
Wolfgang Steiner
Keyword(s):  
Trajectory Tracking ◽  
Multibody Systems ◽  
Degrees Of Freedom ◽  
Inverse Dynamics ◽  
Feedforward Control ◽  
Equations Of Motion ◽  
Three Dimensional ◽  
Differential Algebraic Equations ◽  
State Variables ◽  
Algebraic Equations

This work presents three different approaches in inverse dynamics for the solution of trajectory tracking problems in underactuated multibody systems. Such systems are characterized by less control inputs than degrees of freedom. The first approach uses an extension of the equations of motion by geometric and control constraints. This results in index-five differential-algebraic equations. A projection method is used to reduce the systems index and the resulting equations are solved numerically. The second method is a flatness-based feedforward control design. Input and state variables can be parameterized by the flat outputs and their time derivatives up to a certain order. The third approach uses an optimal control algorithm which is based on the minimization of a cost functional including system outputs and desired trajectory. It has to be distinguished between direct and indirect methods. These specific methods are applied to an underactuated planar crane and a three-dimensional rotary crane.

scholarly journals Shear models and parametric analysis of the PVC geomembrane-cushion interface in a high rock-fill dam

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245245
Author(s):  
Yun-Feng Liu ◽  
Ke Gu ◽  
Yi-Ming Shu ◽  
Xian-Lei Zhang ◽  
Xin-Xin Liu ◽  
...  
Keyword(s):  
Shear Stress ◽  
Friction Coefficient ◽  
Three Dimensional ◽  
Viscous Friction ◽  
Hydraulic Pressure ◽  
Viscous Shear Stress ◽  
Box Counting ◽  
Viscous Shear ◽  
The Stability ◽  
Hysteresis Friction

As a type of flexible impermeable material, a PVC geomembrane must be cooperatively used with cushion materials. The contact interface between a PVC geomembrane and cushion easily loses stability. In this present paper, we analyzed the shear models and parameters of the interface to study the stability. Two different cushion materials were used: the common extrusion sidewall and non-fines concrete. To simulate real working conditions, flexible silicone cushions were added under the loading plates to simulate hydraulic pressure loading, and the loading effect of flexible silicone cushions was demonstrated by measuring the actual contact areas under different normal pressures between the geomembrane and cushion using the thin-film pressure sensor. According to elastomer shear stress, there are two main types of shear stress between the PVC geomembrane and the cushion: viscous shear stress and hysteresis shear stress. The viscous shear stress between the geomembrane and the cement grout was measured using a dry, smooth concrete sample, then the precise formula parameters of the viscous shear stress and viscous friction coefficient were obtained. The hysteresis shear stress between the geomembrane and the cushion was calculated by subtracting the viscous shear stress from the total shear stress. The formula parameters of the hysteresis shear stress and hysteresis friction coefficient were calculated. The three-dimensional box-counting dimensions of the cushion surface were calculated, and the formula parameters of the hysteresis friction were positively correlated with the three-dimensional box dimensions.

scholarly journals Computational Protein Stabilization Can Affect Folding Energy Landscapes and Lead to Domain-Swapped Dimers

2021 ◽  
Author(s):  
Klara Markova ◽  
Antonin Kunka ◽  
Klaudia Chmelova ◽  
Martin Havlasek ◽  
Petra Babkova ◽  
...  
Keyword(s):  
Protein Folding ◽  
Protein Design ◽  
Energy Landscape ◽  
Single Point ◽  
Three Dimensional ◽  
Protein Stabilization ◽  
Dimensional Structure ◽  
Evolutionary Analysis ◽  
Folding Energy

<p>The functionality of a protein depends on its unique three-dimensional structure, which is a result of the folding process when the nascent polypeptide follows a funnel-like energy landscape to reach a global energy minimum. Computer-encoded algorithms are increasingly employed to stabilize native proteins for use in research and biotechnology applications. Here, we reveal a unique example where the computational stabilization of a monomeric α/β-hydrolase enzyme (<i>T</i><sub>m</sub> = 73.5°C; Δ<i>T</i><sub>m</sub> > 23°C) affected the protein folding energy landscape. Introduction of eleven single-point stabilizing mutations based on force field calculations and evolutionary analysis yielded catalytically active domain-swapped intermediates trapped in local energy minima. Crystallographic structures revealed that these stabilizing mutations target cryptic hinge regions and newly introduced secondary interfaces, where they make extensive non-covalent interactions between the intertwined misfolded protomers. The existence of domain-swapped dimers in a solution is further confirmed experimentally by data obtained from SAXS and crosslinking mass spectrometry. Unfolding experiments showed that the domain-swapped dimers can be irreversibly converted into native-like monomers, suggesting that the domain-swapping occurs exclusively <i>in vivo</i>. Our findings uncovered hidden protein-folding consequences of computational protein design, which need to be taken into account when applying a rational stabilization to proteins of biological and pharmaceutical interest.</p>

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