SIST-TP CEN/TR 16303-3:2012

SLOVENSKI STANDARD
SIST-TP CEN/TR 16303-3:2012
01-marec-2012
2SUHPDFHVW6PHUQLFH]DUDþXQDOQLãNHVLPXODFLMHSUHVNXVQLKWUþHQMYVLVWHPH]D
]DGUåHYDQMHYR]LOGHO2EOLNRYDQMHSUHVNXVQHJDY]RUFDLQSUHYHUMDQMH
Road restraint systems - Guidelines for computational mechanics of crash testing against
vehicle restraint system - Part 3: Test Item Modelling and Verification
Rückhaltesysteme an Straßen - Richtlinien für Computersimulationen von
Anprallprüfungen an Fahrzeug-Rückhaltesysteme - Teil 3: Modellierung des
Prüfgegenstands und Überprüfung
Dispositifs de retenue routiers - Recommandations pour la simulation numérique d'essai
de choc sur des dispositifs de retenue des véhicules - Partie 3: Composition et
vérification des modèles numériques de dispositifs d'essai
Ta slovenski standard je istoveten z: CEN/TR 16303-3:2012
ICS:
13.200 3UHSUHþHYDQMHQHVUHþLQ Accident and disaster control
NDWDVWURI
93.080.30 Cestna oprema in pomožne Road equipment and
naprave installations
SIST-TP CEN/TR 16303-3:2012 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST-TP CEN/TR 16303-3:2012

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SIST-TP CEN/TR 16303-3:2012


TECHNICAL REPORT
CEN/TR 16303-3

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 3: Test Item 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 3: Composition et Rückhaltesysteme - Teil 3: Modellierung des
vérification des modèles numériques de dispositifs d'essai Prüfgegenstands und Überprüfung


This Technical Report was approved by CEN on 7 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 16303-3:2012: E
worldwide for CEN national Members.

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Contents
Foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 General considerations on the modelling technique . 5
4 VRS model . 6
5 Verification of the model . 8
6 Collection Data . 10
Annex A Recommendations for the mesh of Finite Element VRS models addressed to crash
simulations . 11
Annex B Recommendations for development of Multi-Body VRS models addressed to crash
simulations . 14
Annex C Phenomena importance ranking table for test Items . 15
Bibliography . 19

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Foreword
This document (CEN/TR 16303-3:2012) 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
1
 Part 5: Analyst Qualification






1
In preparation
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Introduction
This part of this Technical Report is meant to provide the user with all the information necessary for the
development of a complete and efficient numerical model of a test item vehicle in order to properly simulate a
crash event.
The vehicle restraint system (VRS) models represent the test item in a certification test according EN 1317.
The model shall faithfully depict the performance of a VRS so that the performance criteria identified in
EN 1317 can be extracted from the simulation of a vehicle impact with the VRS model. The VRS simulation
can only be assessed in combination with a validated vehicle model described in CEN/TR 16303-2.
There are different types of VRS and they can incorporate concrete, metal, plastic, and composite materials in
their construction. Each system has different modelling requirements and the following manual describes the
guidelines applicable for all VRS. It is important to recognize that the requirements for modelling a deformable
VRS are significantly different from a rigid systems and the latter are not covered in this version of the
guidelines.
This document currently focuses on Finite Element simulation methodologies. Rigid body (or multi-body)
dynamic codes are also used in the development of a VRS. The VRS model requirements are not the same
as for the Finite Element approach and shall be consistent to the methodology. The CM/E group does not yet
have guidelines for the use of rigid body codes and their application for certification requirement cannot be
recommended until they are similarly defined.
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1 Scope
The aim of this Technical Report is to provide a step-by-step description of the development process of a
reliable VRS model for the simulations of full-scale crash tests.
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.
EN 1317-1, Road restraint systems — Part 1: Terminology and general criteria for test methods
EN 1317-2, Road restraint systems — Part 2: Performance classes, impact test acceptance criteria and test
methods for safety barriers including vehicle parapets
EN 1317-3, Road restraint systems — Part 3: Performance classes, impact test acceptance criteria and test
methods for crash cushions
ENV 1317-4, Road restraint systems — Part 4: Performance classes, impact test acceptance criteria and test
methods for terminals and transitions of safety barriers
EN 1317-5, Road restraint systems — Part 5: Product requirements and evaluation of conformity for vehicle
restraint systems
prCEN/TR 1317-6, Road restraint systems — Part 6: Pedestrian restraint system, pedestrian Parapets (under
preparation)
prEN 1317-8, Road restraint systems — Part 8: Motorcycle road restraint systems which reduce the impact
severity of motorcyclist collisions with safety barriers
CEN/TR 16303-2:2011, Road restraint systems — Guidelines for computational mechanics of crash testing
against vehicle restraint system — Part 2: Vehicle Modelling and Verification
CEN/TR 16303-4:2011, Road restraint systems — Guidelines for computational mechanics of crash testing
against vehicle restraint system — Part 4: Validation Procedures
3 General considerations on the modelling technique
3.1 General
Particular attention shall be paid on the geometrical description of the contact areas of the VRS model. Proper
geometry and material properties shall be used. The fixation of the VRS to the roadbed shall correspond to
the test conditions reflected by the standard and the application of the VRS. Modelling of any soil, asphalt,
concrete, etc. element should be documented. Simplifications as well as rigid soil conditions shall be justified
through empirical or engineering analyses independent of the computer model.
The model shall include all significant parts, the connections between the parts, and appropriate boundary
conditions.
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3.2 Finite Element and Multi-body approaches
3.2.1 General
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.
Once the VRS model has been built, it shall be validated with simple tests, such as component tests and then
full-scale dynamic tests. Validation procedures are listed in a separate document (CEN/TR 16303-4). These
validation tests ensure the global response of the model is appropriate and any simplifications of the model
still reproduce the functionality of the system. Numerical stability of the model can be assessed during the
validation process. Subsequently, the model can be used to simulate full-scale crash tests within the
application areas accepted in EN 1317.
Furthermore Computation mechanics when validated can provide support in real life situations that are not
described within EN 1317.
3.2.2 Finite Element guidelines
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 shall 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 Finite Element modelling techniques are identified in Annex A. The most
significant parts of the VRS shall be modelled explicitly with a detailed mesh. Simplifications of certain
structures (bolts, slots, etc.) are acceptable if the appropriate functionality is incorporated. For example, bolted
connections can be replaced by beam elements if the appropriate failure characteristics of the beam elements
are incorporated.
3.2.3 Multi-body guidelines
The MB approach consists in modelling the VRS with a number of rigid bodies connected by means of joints
with specified stiffness characteristics. When reliable and validated data are available, the MB approach is
very useful to perform parametric studies or big test scenario, since the computational cost of the analysis can
be dramatically less than that of the corresponding FEM analysis.
4 VRS model
4.1 Component to be modelled
The majority of elements in a road restraint system lend themselves to direct geometric digitisation in a FE or
MB model. These elements are (but not limited to):
1) posts;
2) horizontal elements;
a. metal beams;
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b. cables;
3) block-out beams / spacers;
4) bolted connections;
5) concrete elements;
6) soil.
General mesh specifications for FE method are listed in Annex A. These specifications are based on the date
of publication (March 2006) level of simulation activities in research and product development. As general
practice, the mesh size and arrangements shall permit the observed (or expected) deformed shape of the
parts. Once a mesh specification has been determined, it becomes a practical issue to determine to which
extent this mesh shall be applied to the entire test object. The level of detail required in the deformed parts
may not need to be applied to all structures that are not subject to local buckling phenomena or other high
stress gradients.
Recommendations for the development of Multi-Body VRS models, addressed to crash simulations method,
are listed in Annex B.
4.2 Coordinate system
The model of the test article should be defined with a consistent coordinate system. The origin of the
coordinate system may differ for the analyst's or system modelling requirements, but the orientation of the axis
should follow the following principles:
X axis oriented along the traffic face of the system for redirective features. Symmetrical structures
(crash cushions) may use the axis of symmetry. The positive direction is in the direction of traffic flow.
Y axis oriented normal to the X axis, parallel to the plane of the road with the positive direction
oriented towards the traffic face of the structure.
Z axis oriented normal to the X-Y plane with the positive direction such that the X-Y-Z triad follows the
right hand rule.
An example of the coordinate system for a safety barrier is shown in Figure 1. Note that that the origin of the
coordinate system is moved away from the VRS for clarity.


a) Plan View b) View a-a

Figure 1 — Vehicle Restraint System Coordinate Systems
The preferred units for the models are millimetres, newton, tons and seconds. These units guarantee
consistency of results and are consistent with the vehicle modelling guidelines in CEN/TR 16303-2.
Nodal coordinates should be defined in the test article's reference frame.
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In case of FE models the fibre direction for all the shell elements should be coherent (same orientation, except
in case of contact definition regions).
4.3 Material models
4.3.1 General
The types of materials used in the test article will define the type of material model definitions used in the
simulation models. The material properties should reflect the properties of the actual part after manufacture.
Thus representative specimen tests should be used as much as possible to represent the current state of the
material properties.
4.3.2 Material modelling for dynamic finite elements simulations
The most common materials for test articles are steel and these materials lend themselves to commonly used
material models. For example in LS-DYNA:
 *MAT_ELASTIC,
 *MAT_PIECEWISE_LINEAR_PLASTICITY,
 *MAT_PLASTIC_KINEMATIC
Each material model has its own input requirements that should be obtained from laboratory tests of coupons
or similar specimens from representative sections of the test article.
Non-metallic materials that may be required to model a test item include concrete, plastic, wood, and soils.
Material models are usually available in commercial programs. For example in LS-Dyna many non-metallic
material models are provided with default parameters. It is strongly recommended that relevant laboratory
tests of these materials are used to define input values.
Documentation for soil models is available [Lewis]. Selection of soil modelling parameters should represent
actual crash test conditions used for model validation. There may be occasions where the soil parameters
should be selected in order to represent a critical design condition.
4.3.3 Material modelling for dynamic Multi-Body simulations
In MB technique elastic-plastic material properties are assigned to spring and damper elements at the hinges
between rigid body elements instead of material models. Spring and damper elements shall consider
nonlinearities such as plasticity, viscosity and load history as appropriate
5 Verification of the model
5.1 General
It is crucial that any simulation models used as part of a standardisation process are reproducible and
repeatable. This requires that the model is numerically stable, i.e. it is not susceptible to divergent solutions
and can complete the simulation run to the specified termination time. These conditions are a necessity for
any analysis and are not special requirements for the CEN standards.
5.2 Basic Requirements
rd
The computer files comprising the test article shall be arranged in such a manner that a 3 party review is
possible. This means than no encryption of data elements will be permitted in simulation models submitted for
standardisation purposes.
The files and any computer scripts required to start the simulation shall be available for review by the Notified
Body when required. If necessary, the simulation shall be run and witnessed by a Notified Body.
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Simulations shall not require restarts or parameter adjustments during the simulation process. Any input files
to be qualified as reference information for the standardisation process shall result in stable simulation runs
(no divergent solutions, termination errors, etc.). Any warning errors issued during the simulation shall be
submitted with the simulation results for review.
For FE simulations limits for changes in the system mass (due to mass-scaling), hourglass energy, and total
system energy are defined in CEN/TR 16303-4.
5.3 Model
...