Discussion: “The Effects of the Lateral Instability of High Center of Gravity Freight Cars” (Wiebe, D., 1968, ASME J. Eng. Ind., 90, pp. 727–735)

1968 ◽  
Vol 90 (4) ◽  
pp. 735-736
Author(s):  
S. G. Guins
Keyword(s):  
Center Of Gravity ◽  
Lateral Instability ◽  
High Center

The Effects of the Lateral Instability of High Center of Gravity Freight Cars

1968 ◽  
Vol 90 (4) ◽  
pp. 727-735
Author(s):  
D. Wiebe
Keyword(s):  
Lateral Force ◽  
Center Of Gravity ◽  
Body Motion ◽  
Lateral Instability ◽  
Vertical Side ◽  
Track Maintenance ◽  
Car Body ◽  
Lift Off ◽  
Lateral Resonance ◽  
High Center

High center of gravity freight cars experience extreme weight shift from side to side as a result of lateral resonance on track with cross-level differences from alternately staggered joints, as well as soft or other local variations in either rail. Dynamic measurements from tests made on test track with controlled 3/4-in. cross-level difference changes illustrate the force and motion magnitudes resulting from resonant and near resonant operating speeds; side bearing loads of 138,000 lb and spring group loads of 100,000 lb, accompanied by center plates separating and wheels lifting. The rotational energy input to the car body can be approximated for a given motion cycle and is proportional to the product of the amplitudes of the track profile and the car body motion. The high lateral (horizontal) forces on the truck at the side bearing and center plate make the truck unstable and cause wheels to lift off the rail on one side. This lateral force at a given end of the car is proportional to the corresponding vertical side bearing load. Freight cars traveling at resonant speed are especially prone to derail on curved track under high wheel-rail friction conditions. Forces and motion generated between the car body, truck, and the track, cause high cyclical stresses and severe wear between components that can shorten equipment life and cause severe track maintenance problems.

Posture stable control of a high center-of-gravity move robot

2004 ◽  
Vol 2004 (0) ◽  
pp. 37-38
Author(s):  
Takashi SATO ◽  
Hideyasu SUMIYA ◽  
Shinichi AOSHIMA ◽  
Masatake SHIRAISHI
Keyword(s):  
Center Of Gravity ◽  
Stable Control ◽  
High Center

Design, Simulation, and Test of Variable Damped Suspensions for M-965 High CG Cars

2001 ◽  
Author(s):  
Armand P. Taillon ◽  
Peter E. Klauser
Keyword(s):  
Vehicle Dynamics ◽  
Center Of Gravity ◽  
Performance Criteria ◽  
Vehicle Performance ◽  
Car Body ◽  
Test Input ◽  
Analysis Methods ◽  
Body Roll ◽  
Dynamics Simulations ◽  
High Center

Abstract This paper reviews design and analysis methods applied in developing a three-piece Coulomb-damped truck arrangement to meet the requirements of specification M-965. This section of the AAR standards specifies performance criteria for high center of gravity cars over twist and roll inputs. The test input is a track section with a series of staggered low joints. These act to excite car body roll. The review demonstrates that properly designed suspension and damping components, in combination with side bearings, will achieve the required performance through the life of the truck. It also demonstrates the effectiveness of accurate vehicle dynamics simulations as a conservative predictor of actual vehicle performance on perturbed track. The design and analysis methods are described in detail. Guidelines are provided to help determine appropriate suspension arrangements for high CG car applications.

Development of the Midwest Guardrail System

2002 ◽  
Vol 1797 (1) ◽  
pp. 44-52 ◽  
Author(s):  
Dean L. Sicking ◽  
John D. Reid ◽  
John R. Rohde
Keyword(s):  
Center Of Gravity ◽  
Full Scale ◽  
Crash Test ◽  
Light Truck ◽  
Satisfactory Performance ◽  
Pavement Overlay ◽  
Improved Performance ◽  
High Center

A revised guardrail system has been developed that should provide greatly improved performance for high-center-of-gravity light truck vehicles. The barrier incorporates W-beam guardrail and standard W6×9 steel posts. Primary changes to the design include raising the standard rail height to 635 mm, moving rail splices to midspan between posts, increasing blockout size, and increasing the size of post bolt slots. All of these changes were designed to improve the barrier’s performance with high-center-of-gravity vehicles. One full-scale crash test was conducted to verify that the guardrail would perform adequately with mini-sized automobiles when raised to 660 mm to the center of the rail. This test proved that the barrier can provide satisfactory performance when mounted at heights ranging from 550 mm (standard guardrail height) up to 660 mm. Hence, the new guardrail design provides approximately 110 mm (4.4 in.) of mounting height tolerance. When installed at the nominal mounting height of 635 mm, a 75-mm pavement overlay could be applied to the roadway without requiring adjustments to the barrier’s height.

Sequential Kinking and Flared Energy-Absorbing End Terminals for Midwest Guardrail System

2005 ◽  
Vol 1904 (1) ◽  
pp. 46-53
Author(s):  
Robert W. Bielenberg ◽  
Dean L. Sicking ◽  
John R. Rohde ◽  
John D. Reid
Keyword(s):  
Center Of Gravity ◽  
Full Scale ◽  
Roadside Safety ◽  
Safety Requirements ◽  
Energy Absorbing ◽  
Crash Tests ◽  
High Center

The Midwest guardrail system (MGS), developed at the Midwest Roadside Safety Facility, was designed to improve the performance of traditional strong-post, W-beam guardrail systems. These improvements include decreasing the potential for rollover with high center-of-gravity vehicles, decreasing the potential for rail rupture at the splice locations, and decreasing the sensitivity of the system to the installation rail height. However, safe guardrail termination options for the MGS must be developed before the system can be implemented on the roadside. Two end terminal designs, the sequential kinking terminal (SKT) and the flared energy-absorbing terminal (FLEAT), were partially redesigned and crash tested in conjunction with the MGS according to NCHRP Report 350 criteria. The new versions of the terminals were named the SKT-MGS and the FLEAT-MGS to designate them for use with the MGS. To evaluate the performance of the terminals with the MGS, a series of four full-scale crash tests was conducted: two redirection tests, NCHRP Report 350 Test Designations 3–34 and 3–35, and two head-on impacts, Test Designations 3–30 and 3–31. The results from the four crash tests were found to meet all relevant safety requirements. The SKT-MGS and FLEAT-MGS end terminals are the first successfully tested end terminals for use with the MGS.

ZMP Based Motion Stability Analysis of a Wheeled Humanoid Robot with Bending Torso

2016 ◽  
Vol 851 ◽  
pp. 497-502
Author(s):  
Si Yu Xia ◽  
Qiang Zhan ◽  
Ahmed Rahmani
Keyword(s):  
Stability Analysis ◽  
Humanoid Robot ◽  
Center Of Gravity ◽  
Chain Rule ◽  
Point Method ◽  
Zero Moment Point ◽  
Motion Stability ◽  
Simulation Results ◽  
Zero Moment ◽  
High Center

Motion stability is the most important issue to be considered when designing a wheeled humanoid robot with bending torso, as it’s easy to capsize because of its high center of gravity. With ZMP (Zero Moment Point) method the motion stability of a wheeled humanoid robot with bending torso was analyzed. At first, the chain rule was used to model the kinematics of the wheeled humanoid robot, and then the process of calculating the ZMP of the robot was presented. With MATLAB the motion stability of the humanoid robot in three typical conditions is simulated and analyzed, and the simulation results were used to optimize some parameters of a wheeled humanoid robot we are designing.

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