CEN/TR 16303-2:2012
(Main)Road restraint systems - Guidelines for computational mechanics of crash testing against vehicle restraint system - Part 2: Vehicle Modelling and Verification
Road restraint systems - Guidelines for computational mechanics of crash testing against vehicle restraint system - Part 2: Vehicle Modelling and Verification
The aim of this Technical Report is to provide a step-by-step description of the development process 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.
Rückhaltesysteme an Straßen - Richtlinien für Computersimulationen von Anprallprüfungen an Fahrzeug-Rückhaltesysteme - Teil 2: Fahrzeugmodellierung und Überprüfung
Ziel dieses Technischen Berichts ist es, eine schrittweise Beschreibung für den Entwicklungsprozess eines zuverlässigen Fahrzeugmodells zur Simulation von voll maßstäblichen Anprallprüfungen zur Verfügung zu stellen und dem Leser eine erste grundlegende Übersicht der Problematik bei den verschiedenen Schritten des Verfahrens der Fahrzeugmodellierung zu vermitteln.
Dispositifs de retenue routiers - Recommandations pour la simulation numérique d'essai de choc sur des dispositifs de retenue des véhicules - Partie 2 : Composition et vérification des modèles numériques de véhicules
Le présent Rapport technique a pour but de fournir une description pas-à-pas du processus de mise au point d'un modèle fiable de véhicules pour les simulations des essais de choc en vraie grandeur donnant au lecteur un premier résumé synthétique des problèmes rencontrés dans les différentes étapes du processus de modélisation de véhicules.
Oprema cest - Smernice za računalniške simulacije preskusnih trčenj v sisteme za zadrževanje vozil - 2. del: Oblikovanje vozil in preverjanje
Ta del standarda CEN/TR 16303 je informativen. V njem so podane splošne informacije o razvoju modela vozila za simulacijo preskusnega trčenja v sisteme za zadrževanje vozil. Opredeliti je mogoče dve različni kategoriji modelov vozil. V prvi kategoriji je podroben model (običajno končni element) vozila ali dela vozila, ki se običajno uporablja v avtomobilski industriji za oceno strukture in strukturnih lastnosti vozila. Drugi tip modela vozila (končni element ali večdelni sistem) se običajno uporablja za oceno zmogljivosti pregrade pri simulaciji preskusnega trčenja v polnem obsegu. V tem primeru mora biti model manj podroben, da se zagotovi stroškovno učinkovito računalniško orodje za analizo več različnih scenarijev trčenja. Hkrati je treba natančno poustvariti pravilne inercijske lastnosti in zunanjo geometrijo vozila. Ta del smernice je namenjen obveščanju uporabnika o vseh potrebnih informacijah za razvoj celovitega in učinkovitega numeričnega modela vozila za pravilno simulacijo trčenja (zgoraj navedena druga kategorija vozil). Zelo podroben model ni primeren zaradi prevelikega dviga računalniških stroškov. S tega stališča se lahko model vozila obravnava kot orodje za analizo trčenja. Cilj tega tehničnega poročila je zagotoviti opis vseh korakov v postopku razvoja zanesljivega modela vozila za simulacije preskusnih trčenj v polnem obsegu, v katerem je naveden prvi sintetični povzetek težav, ki se lahko pojavijo v različnih fazah postopka oblikovanja vozila.
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-marec-2012
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Road restraint systems - Guidelines for computational mechanics of crash testing against
vehicle restraint system - Part 2: Vehicle Modelling and Verification
Rückhaltesysteme an Straßen - Richtlinien für Computersimulationen von
Anprallprüfungen an Fahrzeug-Rückhaltesysteme - Teil 2: Fahrzeugmodellierung und
Überprüfung
Dispositifs de retenue routiers - Recommandations pour la simulation numérique d'essai
de choc sur des dispositifs de retenue des véhicules - Partie 2: Composition et
vérification des modèles numériques de véhicules
Ta slovenski standard je istoveten z: CEN/TR 16303-2:2012
ICS:
13.200 3UHSUHþHYDQMHQHVUHþLQ Accident and disaster control
NDWDVWURI
93.080.30 Cestna oprema in pomožne Road equipment and
naprave installations
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
TECHNICAL REPORT
CEN/TR 16303-2
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
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 routiers - Recommandations pour la Rückhaltesysteme an Straßen - Richtlinien für
simulation numérique d'essai de choc sur des dispositifs Computersimulationen von Anprallprüfungen an Fahrzeug-
de retenue des véhicules - Partie 2: Composition et Rückhaltesysteme - Teil 2: Fahrzeugmodellierung und
vérification des modèles numériques de véhicules Überprüfung
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, France, 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
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2012 CEN All rights of exploitation in any form and by any means reserved Ref. No. CEN/TR 16303-2:2012: E
worldwide for CEN national Members.
Contents Page
Foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 General considerations on the modelling techniques of a vehicle . 5
4 Step by step development of a vehicle for crash test analysis . 7
5 Validation procedures of a vehicle for crash test analysis . 8
Annex A Recommendations for the mesh of Finite Element vehicle models addressed to crash
simulations . 11
Annex B Recommendations and criteria for multi body vehicle models addressed to crash
simulations . 22
Annex C Test methodology . 23
Annex D Phenomena importance ranking table for vehicles . 27
Annex E Phenomena importance ranking table for test item and vehicle interaction . 29
Bibliography . 30
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 document 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 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 Qualification
In preparation
Introduction
This part 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 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 crash 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.
This 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 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.
1 Scope
The aim of this Technical Report is to provide a step-by-step description of the development process 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 application 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 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
details (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 (FEM) 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 crash 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 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 only 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 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 accuracy 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 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 the 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
studies, since the computational cost of the analysis can be dramatically 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 elements:
frame;
body;
suspensions (front and rear);
wheels;
steering system;
glasses;
engine block;
vehicle’s 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 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 single 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,
independent 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, 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 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 certification process.
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, 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 affects 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 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 sampling rate can affect results and needs to set at an appropriate level to give
results convergence;
e) a combination of element size and time st
...
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