UTMUNIVERSITI TEKNOLOGI MALAYSIA

Presented by:

Mohd Syah Rullacmar Bin Mohamed Shuib

(SX101172 MMJ03)Supervised by:

Dr. Zaini Bin Ahmad

CRUSHING BEHAVIOUR AND ENERGY ABSORPTION OF W-BEAM

GUARDRAILUGP 1

Presentation Outline Research Background Research Problem Aims, Objectives & Scopes Planning & Scheduling

Literature Review

Methodology Finite Element Modeling of preliminary model Experimental techniques Preliminary Result Validation of FE model Parametric Study

Conclusion

• Malaysia’s Road Safety Performance;– World’s second highest road fatality per 10,000 registered vehicles– World’s highest percentage of road fatalities per 100,000 population

• Based on IRTAD 2014 Road Safety Annual Report [1]

• Road barriers are paramount in order to ascertain road user safety

• To provide adequate safety for impacting vehicle occupants and

other road users

1. International Traffic Safety Data and Analysis Group (IRTAD). (2014).

Road Safety Annual Report 2014. Retrieved from http://www.internationaltransportforum.org/pub/pdf/14IrtadReport.pdf

Research Background

Research BackgroundTYPES OF ROAD SAFETY BARRIERS

Rigid Barriers• Do not deflect upon impact with limited

energy absorption• Redirect colliding vehicle stably without

rolling movement• Eg: Concrete Barrier

Flexible Barriers• Have high deflection and energy

absorption property by utilizing the energy management principle

• Lowest deceleration force on vehicles• Guides the colliding vehicle forward• Eg: Wire Rope Safety Fence

Semi- Rigid Barriers

• Strong Beam -Weak Post Eliminates vehicle snagging

• Strong Beam -Strong Post Requires minimal defection

• Eg: W-Beam Guardrail• They have low to moderate

deflection distance• The most appropriate type

of safety barrier along the road, Utilized in most parts of the world

TYPES OF ROAD SAFETY BARRIERS

Research Background

Research Statement

• Number of road accident casualties and injuries in the country are still high

• Road barriers are not achieving their targeted goal due to possible design and/ or installation flaw

• Crash tests are notably costly and time consuming

Aims and Objectives/Scopes• The primary objective of the study is to determine the energy

absorption and crushing behaviour of W-Beam guardrail under impact loading.

Scopes of the study

1. Developing preliminary FE models

2. Conducting quasi-static and dynamic test*

3. Developing detailed finite element results for examining the impact

characteristics

4. Validating numerical models by comparing the crushing profiles and load-

deflection response

5. Performing parametric studies

Planning and SchedulingGantt Chart for UGP 1: To aid project progress

According to the Road Engineering Association of Malaysia (2006)• A feature primarily designed to protect road users from

hazardous elements.• Imperative that road barriers are installed correctly as a

preventive measure to reduce accident severity.

According to Ren and Vesenjak (2005)• Crash barriers must withstand the impact of vehicles of a

certain weight from a certain angle while travelling at a certain speed by absorbing the impact energy during the collision.

Crash Barrier Overview

W-Beam Guardrail-Behaviour under Impact

• The W-beam guardrail is classified as semi rigid. It is designed suitably to withstand higher impact angle. To achieve its optimum function, the design of the guardrail should behave as follows: [2].

a) The W-beam barrier must be strong enough to withstand the high axial tensile and bending stresses that occur in the event of vehicle impact.

b) b) The W-beam first bends and then flattens out forming a wide tension band to contain the impacting vehicle

2. REAM, Guidelines on Design and Selection of Longitudinal Traffic Safety Barrier. 2006.

Computer Simulation StudyBorovinsˇek, et al (2007)

• Presented data of a computer simulation on European Standard EN1317 road safety barrier behaviour under impact crash for high containment level

• The studies were ran on a multiprocessor computer platform in order to conduct a simulation using explicit finite element code LS-DYNA

• Simulation data were compared to a large scale experiment of the same road safety design which illustrated a good correlation between the two

Computer Simulation StudyShen, et al (2008)

• Employed the ABAQUS/Explicit v6.5 software to simulate the dynamic response of the safety barrier under impacts

• Estimated the crashworthiness and optimized the design of the W- Beam guardrail system in terms of relative vertical distance from the vehicle centroid to the mounting height of the beam

These and other studies further proves that numerical crash simulation is viable in

designing a crashworthy safety barrier system

Finite Element Modelling of preliminary model

• Important stage in studying impact crash using the FE method• Ensure an accurate representation of the W-Beam Guardrail FE

model to the real model• This study, has simplified certain aspects to reduce modelling time

and simulation time due to time constraint• Results obtained should be well within the range of predicted data

1. Components are modelled using shell elements and general contact interaction is defined as distance between each part for the entire model

2. Verification of the W-Beam Guardrail FE model to determine the capability of general contact and the stability of the element in LS-Prepost for crashworthiness applications

Finite Element Modelling of preliminary model

• W-beam guardrail meets the AASHTO M180 design specification• It has W shaped profile with minimum length of 3180 mm• Designed to 3 mm thickness

Model W- Beam Profile

Parameter Dimension (mm)

Height 86 (+1.0, -2.0)

Width 310 (+5.0, -2.0)

Length 300(+5.0, -2.0)

Pre-Processing - Model has been constructed in Autodesk Professional 2012 and save in compatible format (.iges).

FE analysis of the W-Beam guardrail model has been analyzed by using LS-Prepost 4.2

Analysis Solver – FE model is analyze by using LS-Dyna Manager solver to get the important data such as resultant force, displacement, internal energy, kinetic energy etc

Post-Processing - for sorting, printing and plotting in evaluating and presenting the results using visualization tools

Development of W-Beam Guardrail FE Model

velocity = 10m/s

moving mass

stationary massW-BeamGuardrail

Construction of the W-beam Guardrail Model

Development of W-Beam Guardrail FE Model

Experimental Technique – Simulation(Discretization of FE Model)

Properties W-Beam Material

Material type Piecewise-linear-plasticity (Type 24)Element typeDensity

Shell7850 kg/m³

Modulus of elasticity 200,000 MPaPoisson’s ratio 0.3Yield stress 450.0 MPaFailure plastic strain 0.22

Effective True StressPlastic Strain (MPa)

0.000 450.00.025 508.00.049 560.00.072 591.00.095 613.00.140 643.00.182 668.00.750 840.0

Source from: Atahan, A.O., Finite element simulation of a strong-post W-beam guardrail system. Simulation, 2002. 78(10): p. 587-599.

Material Input in LS-Prepost

Properties Moving Mass Stationary Mass

Material type Rigid (Type 20) Rigid (Type 20)

Element Type Shell Shell

Density *0.000267kg/m³ 7850kg/m³

Modulus of elasticity 200,000 MPa 200,000 MPa

Poisson Ratio 0.3 0.3

Experimental Technique – Simulation(Discretization of FE Model)

Material Input in LS-Prepost

*Based on 200kg weight and material size 500mm x 500mm x 3mm

Based on the analysis, the W-beam was divided into two distinct sections: • Region primarily responded to the impact forces and stresses from the crash• Region that did not actively partake in resisting impact forces- represented

as boundary conditions

• Two types of contact interaction is used to define each of the part• Automatic Node To Surface

• Assigned to the stationary mass and W-Beam guardrail• To ensure there is no penetration between the parts during simulation

• Automatic Single Surface• Moving mass contact

Experimental Technique – Simulation(Discretization of FE Model)

* For the preliminary test, a 5mm element size with a total of 10,760 elements and 11,119 nodes has been created automatically by the software

The W-Beam is expected to deform without any penetration

Experimental Technique – Preliminary Result

Force Displacement Curve from the simulation

Experimental Technique – Preliminary Result

Internal Energy

Experimental Technique – Preliminary Result

Beam Design

Thickness, |(mm)

Width, (mm)

Angle, Ɵ

Output

(CFE), ƞ (SEA),J/kg

P MEAN,(KN)

P MAX,(KN)

W-Beam 3 310 10 11.86% 16.63 38.24 322.36

CFE = Crush Force Efficiency

SEA = Specific Force Absorption

PMEAN = Average force

P MAX = Maximum force

Experimental Technique – Preliminary Result

Experimental Technique – Compression Test

Quasi-Static Compression test by using universal testing machine (INSTRON 600DX)

to obtain the load (N) -displacement(mm) curve

Data will used to validate the FE model

Validation of FE Model

FE model is validate by load-displacement curve and the deformation of the model and from the compression test

To ensure that crashworthiness scenarios are performed as predicted

To verify whether the constraints and the boundary conditions that have been set are correct in order for the model to run successfully without any impending errors.

Parametric Study

To determine the effect of varying geometrical and material parameters during a crash and the energy absorption response.

Beam Design Thickness, |(mm)

Width, (mm)

Angle, Ɵ Output

W-Beam, Thrie Beam

2.5 280 10 -Crush Force Efficiency (CFE), ƞ-Specific Energy Absorption (SEA)-P MEAN-P MAX

2.67 290 12

3 300 14

3.5 310 16

4 320 18

Crush Force Efficiency (CFE), ƞ = PMEAN/PMAX , (0 < ƞ < 1)

Specific Energy Absorption (SEA) = E/m , E= energy absorb , m=mass

Conclusions

• Preliminary simulation show that the W-Beam Guardrail has the capability to absorb impact energy under axial loading

• In this study, an explicit three-dimensional nonlinear finite element code, LS-DYNA, was used to demonstrate how computer simulations can and should be used to supplement full-scale crash tests due to its cost-effectiveness

• Computer simulation technology is shown to be capable of evaluating and improving the impact performance of road-side safety barriers

Thank You For Your

Kind Attention