ASME RT-2-2008 pdf – Safety Standard for Structural Requirements for Heavy Rail Transit Vehicles.
9.2 Linear Elastic Stress Analysis
The carbody stress analysis, based upon the structural sketch, shall consist of a linear-elastic Finite Element Analysis (FEA) using a recognized computer FEA code, supplemented by a manual stress analysis.
The results of the linear stress analysis shall include calculated stresses, allowable stresses, and margins of safety for all structural elements at all design loading conditions required by this Standard. For all linear- elastic load cases, the elastic stability of plates, webs, and flanges shall be calculated for members subject to compression and shear.
The purpose of the manual analysis shall be to examine details of the carbody (such as weld connections, welded and/or bolted joints, fatigue conditions, and column and plate stability) that are not readily handled in the FEA. The format and content of the manual analyses shall include the following as a minimum:
(a) title
(b) sketch of the item to be analyzed with dimensions, applied forces, and other boundary conditions
(c) drawing references
(d) material properties
(e) allowable stress
(f) detailed stress analyses
(g) conclusions
9.3 Crashworthiness Analysis
Time-dependent, large deflection analysis shall be performed using a recognized computer program that has a proven record of use for rail vehicle crashworthiness analysis. The following shall be analyzed:
(a) individual energy absorbing structural elements
(b) individual frangible structural elements (elements in the structural energy absorption zone which shall be designed to fail when overloaded)
(c) each structural energy absorption zone, consisting of the validated energy absorbing and frangible structural elements
(ti) the global carbody, including representative portions of the remainder of the carbody structure
A report of the crashworthiness analysis is required. It shall include computer animations of the results of the time-dependent, large deflection analysis in a self- contained format which can be displayed on a personal computer, or on a commonly available digital video media such as CD or DVD. The computer animations shall contain sufficient detail, view directions, magnifications, and sufficiently high resolution to review the behavior and stability of individual energy absorbing elements, frangible elements, the structural energy absorption zone, the noncrushable structure inboard the crush zones, and the carbody as a whole. The report shall demonstrate the crushing of energy absorbing zones of the carbody is stable, and that the carbody inboard of the energy absorbing zones is not permanently deformed The report shall include a description of the model in sufficient detail to show that it is appropriate for the application. This shall include, as a minimum, descriptions of the structural elements and restraints, and the conditions of the simulation. It shall also include the output of the simulation to verify that the relevant requirements of this Standard and other specified criteria, including force displacement plots, and an itemization of energy absorbed, have been met.
10.1 Objectives
Certain proof of design tests shall be performed in order to demonstrate the strength and stability required by this Standard. It is not necessary to carry out all tests if there are appropriate verification data in existence from previous tests on a similar structure and correlation between the test and calculation has been established. Tests shall be carried out to verify any significant changes to the design or to the performance requirements. There is no need to repeat the tests if the production location is later changed, provided that there is no significant change in the design or manufacturing process of the carbody.
The specific objectives of the tests are to verify the strength of the carbody when subjected to the specified loads, to verify that no permanent deformation is present after removal of specified loads, and to validate analytic models and determine the accuracy of the analyses for load cases not tested. The test program shall comprise, as appropriate, the static simulation of selected design cases, measurements of actual stresses with electric resistance strain gauges or other suitable techniques, and measurement of the structural deformation under loads.