Laser welding has received increased interest in the rail industry due to its outstanding performance in aesthetics, strength, heat affected area, precise control and sealing. This paper introduces the laser-welded stainless steel carbody used in subway cars. The carbody structure, welding methods, strength and fatigue analysis methods, and test verification and validation results are discussed. Firstly, the shear strength of laser welding on stainless steel with different thickness combinations were obtained through tests. The preliminary carbody structure was designed based on the material and welding properties. Then the finite element analysis (FEA) was conducted on the preliminary design to evaluate the strength and optimize the structure. After the optimization was completed, a full-size car was manufactured, and the strength test was performed. In the process of FEA and strength evaluation, the simulation accuracy of different element types and the influence of loading force directions have been considered. Based on the design, simulation and test data, a complete laser welding carbody strength evaluation system was established, which can provide valuable reference for researchers and engineers in the rail vehicle industry. The entire design, analysis and testing process complies with ASME-RT2-2014 and this is also one of the first to implement this standard.

Cold-formed stainless steel is often used in the design and fabrication of passenger rail vehicle car body structures. It is attractive because of its corrosion resistance and the high yield strength in the quarter- and half-hard conditions. One of the complications in designing with this material is its anisotropic properties: the yield strength and stress-strain curve depend upon whether the material is loaded in tension or compression and upon the loading direction relative to the material rolling direction. This phenomenon has been known for some time in the rail industry, and is also well known in the general structural community. This paper is a review of the mechanical and metallurgical properties of cold-formed stainless steel and of current design approaches related to buckling of members made from this product form.

Performing fire endurance tests of railcar floor assemblies in accordance with NFPA 130 is expensive given the minimum size requirements of 3.7 m (12 ft) in length and the full vehicle width. Often it is not financially viable to conduct such tests on several iterations of designs for the purpose of design optimization. Simulations of the fire endurance tests can be performed in place of experiments to provide predictions of floor assembly response of multiple designs at much lower cost. However, capturing the thermo-structural response of the floor assembly requires the ability to model the relevant physical phenomena including softening and weakening of the steel frame, degradation of the fire insulation, and failure of the composite floor. A methodology for performing such simulations was developed under this research addressing each of these phenomena. Temperature dependent thermal and mechanical properties of all modeled materials captures material softening and weakening. Degradation of the insulation was handled through a novel temperature dependent shrinkage approach. Failure models for the sandwich composite floor panels were obtained from literature to predict shear fracture of the core based on a maximum principal shear stress approach and delamination of the core/facesheet based on a maximum strain energy approach. The developed methodology was applied to the simulation of a fire endurance test of an exemplar railcar floor assembly using the commercial finite element solver Abaqus. The assembly was known to hold a passing rating for a 30-minute fire endurance test according to NFPA 130. The floor assembly consisted of a stainless-steel frame, fiberglass insulation, and a ply-metal composite floor. Sequentially coupled thermal and structural models were developed to predict the thermostructural response of the floor assembly for a 30-minute exposure to the ASTM E119 prescriptive fire curve. User-subroutines were utilized to implement the sandwich composite failure models developed for predicted core shear fracture and core/facesheet delamination. The predicted temperature rise on the unexposed surface of the floor assembly after a 30-minute exposure ranged from 50°C to 90°C. The floor assembly was also predicted to maintain structural integrity with the applied crush load, having a center-point vertical deflection of 161 mm after the 30-minute exposure. This resulted in a predicted pass rating for a 30-minute exposure which agrees with the floor assembly’s actual fire rating.

Numerous technologies exist for providing electrical power to transit systems. Where overhead space is costly or where overhead structures may be deemed obtrusive, 3 rd rail is a reliable and cost-effective way to provide considerable power to transit vehicles. Since the early years of railway electrification, 3 rd rail conductors have evolved from steel to aluminum/steel composite to aluminum/stainless steel compositions. Aluminum stainless steel conductors are currently used in approximately 40% of the over 10,000km of 3rd rail systems worldwide. Adoption of this technology in the United States, however, stands at less than 5%. This paper examines aluminum/stainless steel 3 rd rail technology from technical and economic perspectives. The author makes a case for its adoption in new and existing 3 rd rail systems in the United States.