1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationRoad restraint systems Guidelines for computationalmechanics of crash testingagainst vehicle restraint systemPart 2: Vehicle Modelling and VerificationPD CEN/TR 16303-2:2012Natio
2、nal forewordThis Published Document is the UK implementation of CEN/TR 16303-2:2012.The UK participation in its preparation was entrusted by Technical CommitteeB/509, Road equipment, to Subcommittee B/509/1, Road restraint systems.A list of organizations represented on this committee can be obtained
3、 onrequest to its secretary.This publication does not purport to include all the necessary provisions of acontract. Users are responsible for its correct application. The British Standards Institution 2012Published by BSI Standards Limited 2012ISBN 978 0 580 75311 4ICS 13.200; 93.080.30Compliance wi
4、th a British Standard cannot confer immunity fromlegal obligations.This Published Document was published under the authority of theStandards Policy and Strategy Committee on 31 March 2012.Amendments issued since publicationAmd. No. Date Text affectedPUBLISHED DOCUMENTPD CEN/TR 16303-2:2012TECHNICAL
5、REPORT RAPPORT TECHNIQUE TECHNISCHER BERICHT CEN/TR 16303-2 January 2012 ICS 13.200; 93.080.30 English Version Road restraint systems - Guidelines for computational mechanics of crash testing against vehicle restraint system - Part 2: Vehicle Modelling and Verification Dispositifs de retenue routier
6、s - Recommandations pour la simulation numrique dessai de choc sur des dispositifs de retenue des vhicules - Partie 2: Composition et vrification des modles numriques de vhicules Rckhaltesysteme an Straen - Richtlinien fr Computersimulationen von Anprallprfungen an Fahrzeug-Rckhaltesysteme - Teil 2:
7、 Fahrzeugmodellierung und berprfung This Technical Report was approved by CEN on 8 November 2011. It has been drawn up by the Technical Committee CEN/TC 226. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Franc
8、e, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOM
9、ITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. CEN/TR 16303-2:2012: EPD CEN/TR 16303-2:2012CEN/TR 16303-2:2012 (E) 2 Contents Page Foreword 3Introduction . 41
10、Scope 52 Normative references 53 General considerations on the modelling techniques of a vehicle 54 Step by step development of a vehicle for crash test analysis 75 Validation procedures of a vehicle for crash test analysis . 8Annex A Recommendations for the mesh of Finite Element vehicle models add
11、ressed to crash simulations . 11Annex B Recommendations and criteria for multi body vehicle models addressed to crash simulations . 22Annex C Test methodology . 23Annex D Phenomena importance ranking table for vehicles . 27Annex E Phenomena importance ranking table for test item and vehicle interact
12、ion 29Bibliography 30PD CEN/TR 16303-2:2012CEN/TR 16303-2:2012 (E) 3 Foreword This document (CEN/TR 16303-2:2012) has been prepared by Technical Committee CEN/TC 226 “Road equipment”, the secretariat of which is held by AFNOR. Attention is drawn to the possibility that some of the elements of this d
13、ocument may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document consists of this document divided in five Parts under the general title: Guidelines for Computational Mechanics of Crash Testing against Vehicle
14、Restraint System: Part 1: Common reference information and reporting Part 2: Vehicle Modelling and Verification Part 3: Test Item Modelling and Verification Part 4:Validation Procedures Part 5: Analyst Qualification11In preparation PD CEN/TR 16303-2:2012CEN/TR 16303-2:2012 (E) 4 Introduction This pa
15、rt of CEN/TR 16303 is informative. It gives general information for the development of a vehicle model for crash test simulation against vehicle restrain system. Two different categories of vehicle models can be identified. The first category consists of a detailed model (usually finite element) of
16、a vehicle or of a portion of it, typically used in the automotive industry to assess the structural performance and properties of the vehicle. A second type of vehicle model (finite element or multi-body), instead, is typically used to assess the barrier performance in the simulation of full-scale c
17、rash tests. In this case, a less detailed model is required, in order to obtain a computationally cost-effective tool for the analysis of several different crash scenarios. At the same time, it is mandatory to reproduce faithfully the correct inertial properties and outer geometry of the vehicle. Th
18、is Part of the guideline is meant to provide the user with all the information necessary to develop a complete and efficient numerical model of a vehicle in order to properly simulate a crash event (second category of vehicle above). It is not convenient to use a very detailed model, because of the
19、unaffordable increase in the computational costs. In this perspective, the vehicle model can be regarded as a tool for the analysis of a crash event. PD CEN/TR 16303-2:2012CEN/TR 16303-2:2012 (E) 5 1 Scope The aim of this Technical Report is to provide a step-by-step description of the development p
20、rocess of a reliable vehicle model for the simulations of full-scale crash tests giving the reader a first synthetic summary of problems encountered in the different steps of the vehicle modelling process. 2 Normative references The following referenced documents are indispensable for the applicatio
21、n of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. N/A 3 General considerations on the modelling techniques of a vehicle 3.1 General Particular attention shall be paid on
22、the modelling of vehicular kinematics and of the components that realize it: front and rear suspensions, wheels, steering system, etc. The geometry of the vehicle shall be reproduced correctly to simulate the interaction with the barrier. The model shall include only significant parts and few detail
23、s (internal parts should be modelled only regarding their inertial properties, etc.) in order to reduce the computational cost of the model. 3.2 Finite Element and Multi-body approaches Two main modelling approaches can be considered, using two different analysis tools: the Finite Element Method (FE
24、M) and the Multi-Body (MB) approach. Both methods are widely known and broadly used in many fields of engineering, including the Automotive Industry. The first method allows the user to build a very detailed vehicle model and to assess global results such as the barrier or vehicle performance in a c
25、rash test as well as the stress data in a local area of the vehicle. As a counterpart, a FEM analysis requires significant computational costs, thus proving less valid for parametric studies where a large number of simulations may be required. Crash tests finite element (FE) simulations are usually
26、run with a dynamic, non-linear and explicit finite element code. Computer runtime is usually significant, with the order of 30-40 hours on a 2,4 GHz personal computer for the simulation of a full-scale crash test with an effective simulated time of 0,25 second. In fact, the model must include not on
27、ly the vehicle model, but also several meters of roadside barriers (depending on the barrier type, up to 80 meters of barrier) to faithfully reproduce the interaction between the vehicle and the barrier and the boundary conditions. The integration time step is controlled by the minimum dimension of
28、the smallest element of the FE mesh, therefore, the mesh size shall be a trade-off between the need for geometrical and numerical accuracy and computational cost: large elements guarantee a high time step but poor accuracy of the model and possible instabilities, while small elements give a better a
29、ccuracy but a smaller time step. General criteria for the mesh can be identified. The most significant parts of the vehicle shall be modelled explicitly with a detailed mesh (vehicle body, wheels, etc.). Other parts can be modelled implicitly, reproducing their inertial properties (engine) or their
30、function and kinematics (suspension and steering systems). On the other hand, the MB approach consists roughly in modelling the vehicle as a number of rigid bodies connected by means of joints with specified stiffness characteristics. The method is particularly suitable to assess the kinematics of t
31、he vehicle, while less applicable to determine data about levels of stress and strains. When reliable and validated data are available, the MB approach is very useful to perform parametric PD CEN/TR 16303-2:2012CEN/TR 16303-2:2012 (E) 6 studies, since the computational cost of the analysis can be dr
32、amatically less than that of the corresponding FEM analysis. 3.3 General scheme of a vehicle Three main categories of vehicles can be identified: a) passengers cars; b) heavy goods vehicles (HGVs); c) buses. Despite their differences, basically in terms of mass and geometry, they share many common e
33、lements: frame; body; suspensions (front and rear); wheels; steering system; glasses; engine block; vehicles interiors. Regarding the vehicle structure, it must be pointed out that two main different structural options can be identified: the body-on-frame vehicle, typical for trucks and HGVs and the
34、 unit-body vehicle, typical for passenger cars. In the first case, three structural modules that are bolted together to form the vehicle structure can be identified: frame, cabin and box or bed (for a pick-up truck for example). In the second case, the vehicle combines the body and frame into a sing
35、le unit constructed from stamped sheet metal and assembled by spot welding or other fastening methods. This structure is claimed to enhance whole vehicle rigidity and provide for weight reduction. Suspensions can also be subdivided into two main groups: dependent and independent. Generally, independ
36、ent suspensions are used for passenger cars and dependent suspensions are employed in commercial vehicles and buses. Wheels can be single or coupled. The latter configuration is customary for rear wheels of HGVs and buses. 3.4 Vehicle validation considerations Once the vehicle model has been built,
37、it shall be validated with simple tests, both components tests and full-model tests, observing the global response of the model and the behaviour of the single parts (suspensions, wheels). Numerical stability of the model shall be assessed. Subsequently, the model can be used to simulate full-scale
38、crash tests. The same validation approach shall be applied both to FEM and MB modelling. This document can be applied to different modelling techniques, codes or vehicles. Despite different models, the same level of validation shall be required if these models will be applied during the certificatio
39、n process. PD CEN/TR 16303-2:2012CEN/TR 16303-2:2012 (E) 7 Some general comments can be emphasized to accurately predict ASI and THIV, as calculated from a vehicle body mounted accelerometer: a) correct representation of stiffness, strength and inertial properties of the vehicle body part strength,
40、crush mode and timing of front wing, engine firewall, bonnet, A Pillar, floor and other parts affect the accelerations recorded; b) correct representation of tyre interaction with the vehicle body, and hence tyre stiffness for stiffer barriers especially, how the tyre loads the sill and wheel arch a
41、ffects the accelerations; c) accurate capturing of steering, suspension motion, suspension spring and damper properties for weak post systems in particular, longitudinal acceleration is greatly influenced by whether a wheel strikes a post, which can be determined by how the front wheels react/steer
42、from previous strikes; lateral accelerations are affected by the vehicles ability/inability to steer d) sufficient detail for modelling is required for representative vehicle behaviour reducing the model detail and integrity cannot be substituted for lack of computational resource; accelerometer sam
43、pling rate can affect results and needs to set at an appropriate level to give results convergence; e) a combination of element size and time step can produce mass scaling of the vehicle. Mass scaling should be kept to a minimum (aim at less than 2 %) as mass added to the vehicle on initialisation c
44、ould affect the impact results. The added mass should not be concentrated in critical areas. In building a model we make assumptions on what effects are important and to level of accuracy to capture those effects. It is only by conducting a physical test that we discover what physical effects actual
45、ly occur, and the relative importance of those effects. It is also possible that poorly constructed models can produce, what appear to be accurate high level results that match test e.g. peak ASI, THIV and PHD, however, the underlying accelerations can be far from reality. Therefore detailed analysi
46、s of the elements making up the high level results need to be fully understood. 4 Step by step development of a vehicle for crash test analysis Annex A refer to the development of a Finite Element model of a vehicle. In particular: A.1 focuses on the vehicle components to be modelled, describing ext
47、ensively the function of the component and its role in the model as well as some of the ad hoc techniques to achieve an efficient model of the part. On the basis of these considerations the user can basically develop any vehicle model, be it a passenger car or a pick-up truck. A.2 deals with organis
48、ation aspects of the model. Models, in fact, often need to be used by different organisations and pass from user to user. It is, therefore, important that the models have a standard structure and an organisation predictable and easy to understand. A modular model structure is recommended and extensi
49、vely presented in this annex. PD CEN/TR 16303-2:2012CEN/TR 16303-2:2012 (E) 8 A.3 a brief presentation of material models suitable for dynamic analyses is provided. Materials and their properties are fundamental aspects of a reliable model, since the vehicle models that are objective of this manual are going to be used for the simulation of a dynamic event. A.4 includes specific recommendations on the mesh features. Annex B refer to the development of a Multi-Body model
