Mathematical Simulation of Air Suspension Failure and Derailment

2010 ◽  
Author(s):  
Patricia Schreiber ◽  
Nicholas Wilson
Keyword(s):  
Passenger Vehicle ◽  
Contributing Factors ◽  
Transit System ◽  
Contact Conditions ◽  
Vehicle Performance ◽  
Track Geometry ◽  
Vehicle Suspensions ◽  
Air Suspension ◽  
Performance Specifications ◽  
Component Failures

Air suspensions are a commonly used component of modern transit and passenger vehicle suspensions. New vehicle performance specifications usually require testing and analyses with the air suspension inflated and also deflated. However, the tests and analyses usually do not include the dynamic effects that may occur at the instant of deflation. Transportation Technology Center, Inc. (TTCI) recently investigated a revenue service flange climb derailment for a large North American transit system. The derailment occurred on the diverging route of a No. 10 turnout. Initial investigation by the transit system did not identify any track or equipment that showed significant deviations from their normal practices; no obvious cause for the derailment was identified, although the air suspension had been deflated after the derailment. To assist in determining potential contributing factors for the derailment, TTCI conducted NUCARS® simulations of the car negotiating the turnout, using these parameters: • Vehicle dynamic response to local track geometry conditions, including motions of the air suspension; • Sudden deflation of the air suspension; • Wheel and rail profiles. This paper presents the methods used to represent sudden component failures in the NUCARS simulations, including the air suspension deflation. The simulation results show how the sudden deflation of the air suspension combined with local track geometry and wheel/rail contact conditions could contribute to a flange climb derailment.

scholarly journals Laboratory studies of the influence of the working position of the passenger vehicle air suspension on the vibration comfort of children transported in the child restraint system

2021 ◽  
Vol 11 (1) ◽  
pp. 470-482
Author(s):  
Damian Frej ◽  
Andrzej Zuska ◽  
Emilia M. Szumska
Keyword(s):  
Negative Impact ◽  
Rear Seat ◽  
Vehicle Suspension ◽  
Laboratory Studies ◽  
Passenger Vehicle ◽  
Air Suspension ◽  
Child Restraint ◽  
Empirical Tests ◽  
Vertical Vibrations ◽  
Child Restraint System

Abstract The article presents the results of laboratory tests on the influence of the choice of the vehicle suspension position and the method of mounting child seats on the vibration comfort of children transported in them. Two child seats were used in the work. The B seat was attached to the vehicle with the ISOfix system, while the A seat was attached in the classic way (with seat belts). During the tests, the values of vertical vibrations were recorded on the seats of child seats, the rear seat of the vehicle and on the basis of ISOfix. The analyzed systems, depending on the method of mounting a child seat, may be characterized by two different vibration transmission chains. They depend on the method of fixing the child seat (the classic way of fixing the seat and the ISOFIX system). The article presents the results of empirical tests carried out at the EUSAMA SA.640 stand, which in these tests acted as a vibration generator with a frequency of 0 to 25 Hz. The analysis of the obtained results confirmed the observations published in previous articles about the negative impact of the use of the ISOfix base on the vibrational comfort of children.

Parametric Simulation of Rolling Contact Fatigue

2008 ◽  
Author(s):  
Scott M. Cummings ◽  
Patricia Schreiber ◽  
Harry M. Tournay
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Wear Model ◽  
Primary Methods ◽  
Vehicle Performance ◽  
Track Geometry ◽  
Advantages And Disadvantages ◽  
Defect Prevention ◽  
Design Speed

Simulations of dynamic vehicle performance were used by the Wheel Defect Prevention Research Consortium (WDPRC) to explore which track and vehicle variables affect wheel fatigue life. A NUCARS® model was used to efficiently examine the effects of a multitude of parameters including wheel/rail profiles, wheel/rail lubrication, truck type, curvature, speed, and track geometry. Results from over 1,000 simulations of a loaded 1,272 kN (286,000-pound) hopper car are summarized. Rolling contact fatigue (RCF) is one way that wheels can develop treads defects. Thermal mechanical shelling (TMS) is a subset of wheel shelling in which the heat from tread braking reduces a wheel’s fatigue resistance. RCF and TMS together are estimated to account for approximately half of the total wheel tread damage problem [1]. Other types of tread damage can result from wheel slides. The work described in this paper concerns pure RCF, without regard to temperature effects or wheel slide events. Much work has been conducted in the past decade in an attempt to model the occurrence of RCF on wheels and rails. The two primary methods that have gained popularity are shakedown theory and wear model. The choice of which model to use is somewhat dependent on the type of data available, as each model has advantages and disadvantages. The wear model was selected for use in this analysis because it can account for the effect of wear on the contacting surfaces and is easily applied to simulation data in which the creep and creep force are available. The findings of the NUCARS simulations in relation to the wear model include the following: • Degree of curvature is the single most important factor in determining the amount of RCF damage to wheels; • The use of trucks (hereafter referred to as M-976) that have met the Association of American Railroads’ (AAR) M-976 Specification with properly maintained wheel and rail profiles should produce better wheel RCF life on typical routes than standard trucks; • In most curves, the low-rail wheel of the leading wheelset in each truck is most prone to RCF damage; • While the use of flange lubricators (with or without top of rail (TOR) friction control applied equally to both rails) can be beneficial in some scenarios, it should not be considered a cure-all for wheel RCF problems, and may in fact exacerbate RCF problems for AAR M-976 trucks in some instances; • Avoiding superelevation excess (operating slower than curve design speed) provides RCF benefits for wheels in cars with standard three-piece trucks; • Small track perturbations reduce the overall RCF damage to a wheel negotiating a curve.

Global Optimal Design and Dynamic Validation of an Independent Double Wishbone Air Suspension Using Genetic Algorithm

2014 ◽  
Vol 543-547 ◽  
pp. 374-378
Author(s):  
Jing Zhao ◽  
Pak Kin Wong ◽  
Tao Xu ◽  
Rui Deng ◽  
Cai Yang Wei ◽  
...  
Keyword(s):  
Genetic Algorithm ◽  
Optimal Design ◽  
Parametric Design ◽  
Dynamic Performance ◽  
Vehicle Performance ◽  
Air Suspension ◽  
Before And After ◽  
Wheel Alignment ◽  
Global Optimal ◽  
Suspension Structure

In view of the drawbacks of the traditional optimal methods in the suspension structure optimization, this paper elaborates a genetic algorithm (GA) based global optimal design so as to improve the vehicle performance. Firstly, an independent double wishbone air suspension (IDWAS) is constructed. After defining the linkage relation of the guide mechanism of the IDWAS, the model is verified followed with the parametric design. Furthermore, in consideration of the prescribed targets of the vehicle kinematics, the wheel alignment parameters (WAPs) are selected as the objectives of the optimal design of the vehicle kinematics. Apart from the kinematic analysis of the IDWAS, dynamic analysis before and after optimization as well as the traditional independent double wishbone suspension (TIDWS) are also conducted. Numerical results show that the changes of the WAPs are within a certain range and the guide mechanism follows the prescribed constraints. Simulation results show that the IDWAS is superior to the TIDWS, while the optimized IDWAS has a slight improvement as compared to the original IDWAS in dynamic performance of the suspension.

Design of Rapid Transit Equipment for the San Francisco Bay Area Rapid Transit System

1966 ◽  
Vol 8 (4) ◽  
pp. 339-346 ◽  
Author(s):  
Carl W. Sundberg ◽  
Montgomery Ferar
Keyword(s):  
San Francisco ◽  
Environmental Control ◽  
San Francisco Bay ◽  
San Francisco Bay Area ◽  
Rapid Transit ◽  
Passenger Vehicle ◽  
Transit System ◽  
Bay Area ◽  
Appearance Design ◽  
System Requirements

Automobile traffic is threatening to overwhelm the cities of the San Francisco Bay Area, and an advanced mass transit system is being built by the Bay Area Rapid Transit District (BARTD) to help alleviate this problem. This article describes the design and development of the passenger vehicle for this system. BARTD system requirements and car design criteria are discussed, and the conceptual design and detailed development of passenger accommodations, environmental control provisions, lighting, ingress/egress, visibility and appearance design featurea are presented. The requirements for and the detailed design of the train attendant's pod are also discussed. A prototype car has been designed with primary emphasis on those human factors considerations that are expected to induce 200,000 commuters to use the system in preference to private automobiles. Public reactions to the prototype vehicle will be employed to refine and improve upon the design prior to its introduction into service in 1971.

Analytical Elastic Modeling of Rail and Fastener Longitudinal Response

2021 ◽  
pp. 036119812098584
Author(s):  
Matheus Trizotto ◽  
Marcus S. Dersch ◽  
J. Riley Edwards ◽  
Arthur Lima
Keyword(s):  
Analytical Model ◽  
Critical Role ◽  
Valuable Insight ◽  
Railroad Track ◽  
Track Geometry ◽  
Longitudinal Response ◽  
Ballasted Track ◽  
Track Stiffness ◽  
Component Failures ◽  
Insight Into

The rail fastening system plays a critical role in maintaining proper railroad track geometry by transferring vertical, lateral, and longitudinal forces from the rails to crossties. Broken spikes in elastic fastening systems have been linked to inadequate transfer of longitudinal loads, posing a safety risk for timber crosstie ballasted track. Longitudinal track demand caused by passing trains has been investigated in previous research, but the magnitude and distribution of longitudinal fastener loads is not well understood or documented. To address these track component failures and improve fastener design, this paper presents a validated analytical model that estimates longitudinal rail seat loads, advancing current formulations to focus specifically on the rail seat. The validated method was used to quantify the distribution and magnitude of longitudinal loads in both the rail and fastening system caused by passing trains. Further, this paper quantifies the effect of track stiffness, number of powered locomotives, and wheel spacing on these distributions and magnitudes. This information provides valuable insight into the specific type of spike failures that have led to at least ten derailments and the requirement of manual walking inspections on multiple North American heavy axle load railroads as detailed in this paper. Further, this method can be used to quantify the longitudinal fastener loads for different track conditions to advance the mechanistic-empirical track design philosophy for elastic fastening systems.

Load and response quantification of direct fixation fastening systems for heavy rail transit infrastructure

2021 ◽  
pp. 095440972098703
Author(s):  
Arthur de O Lima ◽  
J Riley Edwards ◽  
Luis W Chavez Quiroz ◽  
Yu Qian ◽  
Marcus S Dersch
Keyword(s):  
Life Cycle Cost ◽  
Field Performance ◽  
Quantitative Information ◽  
Field Investigation ◽  
Operating Conditions ◽  
Rail Transit ◽  
Transit System ◽  
Track Geometry ◽  
Vertical Loading ◽  
Heavy Rail

Ballastless track (i.e. slab track) systems are used extensively in passenger rail applications for improved track stability, alignment control, vibration, and life cycle cost (LCC) benefits. These systems regularly rely on Direct Fixation (DF) fasteners to connect the rail to the structure. Field performance observations have indicated that even under similar track geometry and train operating conditions, the DF fasteners useful life varies widely. Meanwhile, a review of literature reveals that there is limited prior research to guide optimization of DF fastener designs for heavy rail transit. Therefore, researchers at the University of Illinois at Urbana-Champaign (UIUC) conducted a field investigation at three sites on a United States legacy heavy rail transit system to quantify wheel-rail interface loading demands and DF fastener response. Track response variance across similar track geometry was found. Wheel loads ranged between 2.7 to 18.2 kip (12.0 to 81.0 kN) and 0.9 to 12.4 kip (4.0 to 55.2 kN) for vertical and lateral loads, respectively. Lateral rail head displacements ranged between −0.05 to 0.16 inches (−1.27 to 4.06 mm) while dynamic lateral stiffness ranged from 42 to 62 kip/in. (7.3 to 10.8 kN/mm), indicating a low stiffness ratio for the DF fastener studied. Differences in behavior are attributed to dynamic vehicle-track interaction, the relationship between balanced and operating speeds, and differences in track gauge between sites. A comparison of vertical loading results with two additional heavy rail transit agencies shows Burr distributions that accurately represent the loading demands. Results from this study provide quantitative information that can be leveraged to improve heavy rail transit DF fastening system design and development of representative design validation testing protocols.

Sign in / Sign up

Export Citation Format

Share Document