Towards Eliminating the Displacement Bias Due to Out-Of-Plane Motion in 2D Inverse Problems: A Case of General Rigid-Body Motion

Strain ◽  
2014 ◽  
Vol 51 (1) ◽  
pp. 55-70 ◽  
Author(s):  
M. Z. Siddiqui
Keyword(s):  
Inverse Problems ◽  
Rigid Body ◽  
Plane Motion ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Out Of Plane

Eigenanalysis of the Rigid Body Motion Effect on Elastic Systems

1983 ◽  
Vol 105 (4) ◽  
pp. 461-466 ◽  
Author(s):  
A. Maher ◽  
A. L. Schlack
Keyword(s):  
Eigenvalue Problem ◽  
Rigid Body ◽  
Free Vibration Analysis ◽  
Plane Motion ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Computer Calculations ◽  
Motion Effect ◽  
Ritz Procedure ◽  
The Difference

In this paper, the influence of rigid body motion on the behavior of a vibrating elastic system is treated by the development of a difference eigenvalue problem. The maximum possible changes in eigenfrequencies due to removal of constraints are obtained by the employment of the bound approach [1, 2]. As an application to a structural system the Rayleigh-Ritz procedure is employed for constructing the difference eigenvalue problem. Discussion of the use of the method for various types of engineering problems is outlined. An example of a free vibration analysis of a simply supported beam in plane motion with a nonuniform mass and elasticity distribution is solved. A comparison between computer calculations and previously published results is presented.

Rigid Body Motion Conversion due to Collision

2013 ◽  
Vol 705 ◽  
pp. 540-545
Author(s):  
Svetlana Polukoshko
Keyword(s):  
Rigid Body ◽  
Cylindrical Body ◽  
Plane Motion ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Impact Theory ◽  
Post Impact ◽  
Task Oriented ◽  
The Impact ◽  
Impact Motion

The impact phenomenon may be used for task-oriented changing of rigid body motion. When moving body encounters with some obstacle all parameters of motion are changing as a result of impact and trajectory and type of motion are also changing. In this work the conversion of translatory motion of prismatic rigid body into plane or rotation and conversion of plane motion of cylindrical body due to impact are considered. The conditions of conversion of one type of motion into another and parameters post-impact motion are studied. Problems are solved in the framework of rigid body motion, using rigid body impact theory. Studying of such phenomena is important for location of parts on industrial conveyors, feeders, etc.

Temperature Dependence of the Rigid-Body Motion of Anthraquinone

1998 ◽  
Vol 54 (3) ◽  
pp. 308-315 ◽  
Author(s):  
Y. Fu ◽  
C. P. Brock
Keyword(s):  
Rigid Body ◽  
Temperature Dependence ◽  
Cross Sections ◽  
Large Amplitude ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Internal Vibration ◽  
Use Of Data ◽  
Out Of Plane ◽  
Plane Displacement

Anthraquinone has been studied at five temperatures between 296 and 162 K. The unsatisfactory agreement factors obtained in earlier studies probably resulted from the use of data collected from twinned crystals; needle-like crystals with approximately equidimensional cross sections are usually contact twins related by reflection across (102¯). The temperature dependence of the T and L tensors is normal. The out-of-plane displacement parameters of the O atom indicate a large-amplitude internal vibration.

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.

Computation of Nonlinear Response of Hydraulically Actuated Structures

1997 ◽  
Author(s):  
T. D. Burton ◽  
C. P. Baker ◽  
J. Y. Lew
Keyword(s):  
Rigid Body ◽  
Flexible Structures ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Flexible Beam ◽  
Test Bed ◽  
Ode Models ◽  
Hydraulically Actuated ◽  
Pressure Dynamics ◽  
Low Order

Abstract The maneuvering and motion control of large flexible structures are often performed hydraulically. The pressure dynamics of the hydraulic subsystem and the rigid body and vibrational dynamics of the structure are fully coupled. The hydraulic subsystem pressure dynamics are strongly nonlinear, with the servovalve opening x(t) providing a parametric excitation. The rigid body and/or flexible body motions may be nonlinear as well. In order to obtain accurate ODE models of the pressure dynamics, hydraulic fluid compressibility must generally be taken into account, and this results in system ODE models which can be very stiff (even if a low order Galerkin-vibration model is used). In addition, the dependence of the pressure derivatives on the square root of pressure results in a “faster than exponential” behavior as certain limiting pressure values are approached, and this may cause further problems in the numerics, including instability. The purpose of this paper is to present an efficient strategy for numerical simulation of the response of this type of system. The main results are the following: 1) If the system has no rigid body modes and is thus “self-centered,” that is, there exists an inherent stiffening effect which tends to push the motion to a stable static equilibrium, then linearized models of the pressure dynamics work well, even for relatively large pressure excursions. This result, enabling linear system theory to be used, appears of value for design and optimization work; 2) If the system possesses a rigid body mode and is thus “non-centered,” i.e., there is no stiffness element restraining rigid body motion, then typically linearization does not work. We have, however discovered an artifice which can be introduced into the ODE model to alleviate the stiffness/instability problems; 3) in some situations an incompressible model can be used effectively to simulate quasi-steady pressure fluctuations (with care!). In addition to the aforementioned simulation aspects, we will present comparisons of the theoretical behavior with experimental histories of pressures, rigid body motion, and vibrational motion measured for the Battelle dynamics/controls test bed system: a hydraulically actuated system consisting of a long flexible beam with end mass, mounted on a hub which is rotated hydraulically. The low order ODE models predict most aspects of behavior accurately.

Structures of the Phosphazenes [ClC(NPCl3)2]+PCl6 − and [CH3C(NPCl3)2]+SbCl6 − at 90 K

1997 ◽  
Vol 53 (6) ◽  
pp. 953-960 ◽  
Author(s):  
F. Belaj
Keyword(s):  
Rigid Body ◽  
Motion Analysis ◽  
Rigid Body Motion ◽  
Body Motion ◽  
Torsion Angles ◽  
Ionic Compounds ◽  
Intramolecular Motions

The asymmetric units of both ionic compounds [N-(chloroformimidoyl)phosphorimidic trichloridato]trichlorophosphorus hexachlorophosphate, [ClC(NPCl3)2]+PCl^{-}_{6} (1), and [N-(acetimidoyl)phosphorimidic trichloridato]trichlorophosphorus hexachloroantimonate, [CH3C(NPCl3)2]+SbCl^{-}_{6} (2), contain two formula units with the atoms located on general positions. All the cations show cis–trans conformations with respect to their X—C—N—P torsion angles [X = Cl for (1), C for (2)], but quite different conformations with respect to their C—N—P—Cl torsion angles. Therefore, the two NPCl3 groups of a cation are inequivalent, even though they are equivalent in solution. The very flexible C—N—P angles ranging from 120.6 (3) to 140.9 (3)° can be attributed to the intramolecular Cl...Cl and Cl...N contacts. A widening of the C—N—P angles correlates with a shortening of the P—N distances. The rigid-body motion analysis shows that the non-rigid intramolecular motions in the cations cannot be explained by allowance for intramolecular torsion of the three rigid subunits about specific bonds.

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