scholarly journals On the equilibriums stability in an approximate problem of the dynamics of a rigid body with a suspension point vibrating along an inclined straight line

2021 ◽  
Vol 1959 (1) ◽  
pp. 012007
Author(s):  
Mikhail Belichenko
Keyword(s):  
Rigid Body ◽  
Suspension Point ◽  
Approximate Problem ◽  
Straight Line

A planar reconfigurable linear rigid-body motion linkage with two operation modes

2014 ◽  
Vol 228 (16) ◽  
pp. 2985-2991 ◽  
Author(s):  
Guangbo Hao ◽  
Xianwen Kong ◽  
Xiuyun He
Keyword(s):  
Rigid Body ◽  
Single Mode ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Reference Guide ◽  
Revolute Joints ◽  
Operation Modes ◽  
Straight Line ◽  
Motion Stage ◽  
Motion Mode

A planar reconfigurable linear (also rectilinear) rigid-body motion linkage (RLRBML) with two operation modes, that is, linear rigid-body motion mode and lockup mode, is presented using only R (revolute) joints. The RLRBML does not require disassembly and external intervention to implement multi-task requirements. It is created via combining a Robert’s linkage and a double parallelogram linkage (with equal lengths of rocker links) arranged in parallel, which can convert a limited circular motion to a linear rigid-body motion without any reference guide way. This linear rigid-body motion is achieved since the double parallelogram linkage can guarantee the translation of the motion stage, and Robert’s linkage ensures the approximate straight line motion of its pivot joint connecting to the double parallelogram linkage. This novel RLRBML is under the linear rigid-body motion mode if the four rocker links in the double parallelogram linkage are not parallel. The motion stage is in the lockup mode if all of the four rocker links in the double parallelogram linkage are kept parallel in a tilted position (but the inner/outer two rocker links are still parallel). In the lockup mode, the motion stage of the RLRBML is prohibited from moving even under power off, but the double parallelogram linkage is still moveable for its own rotation application. It is noted that further RLRBMLs can be obtained from the above RLRBML by replacing Robert’s linkage with any other straight line motion linkage (such as Watt’s linkage). Additionally, a compact RLRBML and two single-mode linear rigid-body motion linkages are presented.

Design of a Continuum Mechanism that Matches the Movement of an Eight-bar Linkage

2020 ◽  
pp. 1-11
Author(s):  
Xueao Liu ◽  
J. Michael McCarthy
Keyword(s):  
Finite Element Analysis ◽  
Rigid Body ◽  
Design Methodology ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Initial Structure ◽  
Element Analysis ◽  
Kinematic Synthesis ◽  
Generic Structure ◽  
Straight Line

Abstract This paper presents a design methodology for mechanisms consisting of a single continuous structure, continuum mechanisms, that blends the kinematic synthesis of rigid-body mechanisms with topology optimization for compliant mechanisms. Rather than start with a generic structure that is shaped to achieve a required force deflection task for a compliant mechanism, our approach shapes the initial structure based on kinematic synthesis of a rigid body mechanism for the required movement, then the structure is shaped using Finite Element Analysis to achieve the required force deflection relationship. The result of this approach is a continuum mechanism with the same workpiece movement as the rigid link mechanism when actuated. An example illustrates the design process to obtain an eight-bar linkage that guides its workpiece in straight-line rectilinear movement. We show that the resulting continuum mechanism provides the desired rectilinear movement. A 210 mm physical model machined from Nylon-6 is shown to achieve 21.5mm rectilinear movement with no perceived deviation from a straight-line.

A Computationally Efficient Planar Rigid Body Velocity Measure

2009 ◽  
Author(s):  
Luis E. Criales ◽  
Joseph M. Schimmels
Keyword(s):  
Rigid Body ◽  
Rigid Bodies ◽  
Body Motion ◽  
Computationally Efficient ◽  
Straight Line ◽  
Body Velocity ◽  
Velocity Measure ◽  
Rigid Body Motions ◽  
Line Path ◽  
Planar Motions

A planar rigid body velocity measure based on the instantaneous velocity of all particles that constitute a rigid body is developed. This measure compares the motion of each particle to an “ideal”, but usually unobtainable, motion. This ideal motion is one that would carry each particle from its current position to its desired position on a straight-line path. Although the ideal motion is not a valid rigid body motion, this does not preclude its use as a reference standard in evaluating valid rigid body motions. The optimal instantaneous planar motions for general rigid bodies in translation and rotation are characterized. Results for an example planar positioning problem are presented.

On the Planar Damped Linear Vibrations of a Rigid Body

1999 ◽  
Author(s):  
Pat Blanchet ◽  
Harvey Lipkin
Keyword(s):  
Rigid Body ◽  
Planar Motion ◽  
Straight Line ◽  
Linear Vibrations

Abstract The planar motion associated with a damped mode of a vibrating rigid body is actually not well understood. This paper shows that a damped mode is a rotation about a point that is either translating along a straight line or is stationary, depending on how much damping is present. The transition between each type of damping is explained and an example illustrates the results.

Using Rigid-Body Mechanism Topologies to Design Path Generating Compliant Mechanisms

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Kai Zhao ◽  
James P. Schmiedeler
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Mesh Network ◽  
Optimal Topology ◽  
Optimal Size ◽  
Path Generation ◽  
Dimensional Synthesis ◽  
Straight Line ◽  
Rigid Body Transformation

For a path generation problem, this paper uses the base topology of a single degree-of-freedom (DOF) rigid-body mechanism solution to synthesize fully distributed compliant mechanisms that can trace the same path. Two different strategies are proposed to employ the base topology in the structural optimization so that its design space size can be intelligently reduced from an arbitrary complexity. In the first strategy, dimensional synthesis directly determines the optimal size and shape of the compliant mechanism solution while maintaining the exact base topology. In the second, the base topology establishes an initial mesh network to determine the optimal topology and dimensions simultaneously. To increase the possibility of converging to an optimal design, the objective metrics to evaluate the path generation ability are computed in a novel manner. A section-by-section analysis with a rigid-body transformation is implemented to examine the full path of each candidate mechanism. A two-objective genetic algorithm (GA) is employed to find a group of viable designs that tradeoff minimizing the average Euclidean distance between the desired and actual paths with minimizing the peak distance between corresponding points on those paths. Two synthesis examples generating straight-line and curved paths are presented to demonstrate the procedure's utility.

Measurements and Correlations of Slider Vibrations and Wear

1999 ◽  
Vol 122 (1) ◽  
pp. 374-380 ◽  
Author(s):  
M. D. Bryant ◽  
David York
Keyword(s):  
Kinetic Energy ◽  
Rigid Body ◽  
Sliding Wear ◽  
Quantitative Relationship ◽  
Total Kinetic Energy ◽  
Vibration Data ◽  
Surface Time ◽  
Straight Line ◽  
Rate Versus ◽  
Counter Surface

Studies have shown that micro-vibrations (10–100 μm amplitude, 10 to 100 Hz) of a slider can reduce sliding wear 50 percent, especially rigid body rocking motions that continuously realign the slider face with respect to the counter surface. In this article, clearances between a carbon sample and its holder were varied while sliding over a slightly wavy (8 to 20 μm) steel surface. Undulations on the counter surface induced rigid body vibrations of the slider. Clearances between sample and holder kinematically restricted rigid body rocking motions of the slider: larger clearances permitted more rocking. Measured were motions of the slider, including translations normal to the counter surface, and rotations about axes parallel to the counter surface. Time traces of these displacements were plotted at different sliding speeds. Frequency content and kinetic energies for each measured degree of freedom and the total were extracted. We sought correlations between measured wear and vibration data. Fractional changes in wear rate versus fractional changes in total kinetic energy clustered about a straight line. From these measurements, we found a quantitative relationship between amount of wear and total kinetic energy of vibration. [S0742-4787(00)05001-3]

Sign in / Sign up

Export Citation Format

Share Document