Design of automobile front bumper for collision energy Attenuation
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This document presents research on designing an automobile front bumper to better attenuate collision energy. The study aims to reduce passenger and vehicle body damage from collisions. Three materials - ABS plastic, carbon fiber reinforced plastic, and glass fiber reinforced plastic - were modeled and analyzed using CATIA and ANSYS software. Dynamic impact simulations were performed with the bumper striking a fixed support at 10 m/s. Von Mises stress and deformation results from ANSYS were highest for carbon fiber, followed by glass fiber and ABS plastic. A mathematical model was also developed to calculate impact stress, and results closely matched those from ANSYS simulations. In conclusion, composite materials showed better energy absorption during impact testing compared to ABS plastic.
![INTERNATIONAL RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY (IRJET) E-ISSN: 2395 -0056
VOLUME: 04 ISSUE: 02 | FEB -2017 WWW.IRJET.NET P-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 819
DESIGN OF AUTOMOBILE FRONT BUMPER FOR COLLISION ENERGY
ATTENUATION
1. Bharat P. Patil, 2. Prashant N. Ulhe
1. M. E. Student, Mechanical Dept. SSBT’s COET, Bambhori, Jalgaon, Maharashtra, India.
2. Assistant Professor, Mechanical Dept. SSBT’s COET, Bambhori, Jalgaon, Maharashtra, India.
------------------------------------------------------------------------***-------------------------------------------------------------------------
Abstract – While designing the bumper in the automobile
considering an impact during collision is important. The
design must improve the ability to absorb more impact load,
reducing stress, and increase the protection of the front car
component. The method have been employed was study the
front bumper system, design using CATIA software, and
analyze the alternative front bumper material using ANSYS
software.
The aim of this work is to reduce the degree of damage to
passengers, and vehicle’s body caused by vehicle collisions.
Crash phenomena involving road vehicle were studied for the
purpose of developing an impact attenuation design that can
withstand specific speed.
Key Words: front bumper;composites;collision;ANSYS.
I. INTRODUCTION
In an automobile's structure bumper is the front-most or
rear-most part. It is used to sustain an impact and reduce or
prevent damage to the passengers, vehicle's frame or safety
systems of car during low speed collision. Generally steel
and Aluminum has been the dominant material for vehicle
body in old days. But, now a days the front of car bumper is
made by composite that suit for the commercial front
bumper (1). The bumper is use to cover the bumper beam
that connected to the car’s frame.
Even it could prevent a small damage for the car, the front
bumper important as an aesthetical value. Composite are
the best materials for bumper which are aesthetically
pleasant, lighter weight and offer many more substantial
advantages (2).
II. PROBLEM STATEMENT
Now a days accidents are frequent and cause damage to a
vehicle’s body and became threat to human life. Hence
crashworthiness of automobile bumper is essential. Also
the cost for replacing bumper is quite expensive especially
if surrounding area or part also damaged.
Customer also blame to the manufacture that the bumper
easily gets damaged although the collision was slow. The
material of the bumper should be analyzed to find the
alternative material that can improve the crashworthiness,
also have toughness.
III. LITERATURE SURVEY
Until now many research and experiment has done on
bumper design. Ramin Hosseinzadeh et al. [1] (2004), has
studied on parametric research of automotive composite
bumper beams subjected to low-velocity impacts and
concluded that fuel efficiency and emission gas regulations
are the main causes for reducing the weight of passengers’
cars by the use of composite material structures. Hence the
composite will probably the best material to produce an
effective bumper.
As per Marzbanrad J. M. et.al [2] the important parameters
considered for design and analysis of an automotive front
bumper beam to improve the crashworthiness design in
low-velocity impact are material, thickness, shape and
impact condition.
Gintautas Dundulis et al. [3], Static analytical and
experimental research of shock absorber to safe guard the
nuclear fuel assemblies. Ping Yang et al. [4], Design, test
and modeling evaluation approach of a novel Si-oil shock
absorber for protection of electronic equipment in moving
vehicles.
In their study M. M. Davoodi et al. [5] studied on conceptual
design of polymer composite automotive bumper energy
absorber. It was observed that, major injury due to impact
velocity of around 20-30 km/h was affected to the knee
ligament. They proposed fiber reinforced epoxy composite
material for bumper as a pedestrian energy absorber. The
energy absorption capacity was sufficient for pedestrian
impact and it could possible to use as substitute for the
existing materials for low impact collision.
IV. SOLID MODELING
A solid model is better because for an object it provides
more complete representation than its surface model. It
provides more topological information in addition to the
geometrical information which helps to represent the solid
unambiguously. There are different software that are used
for generating these solid models like CATIA and Pro-E. In
this project the frame is modeled by using CATIA V5. All
the parts that are required for constructing the frame are
modeled in part module by using different commands like
extrude, loft, fillet, shell etc. as shown in Fig. 1.](https://image.slidesharecdn.com/irjet-v4i2160-171117093845/85/Design-of-automobile-front-bumper-for-collision-energy-Attenuation-1-320.jpg)
![INTERNATIONAL RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY (IRJET) E-ISSN: 2395 -0056
VOLUME: 04 ISSUE: 02 | FEB -2017 WWW.IRJET.NET P-ISSN: 2395-0072
© 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 823
6) Neglecting effect of bending and shearing of Pole
and Bumper for analysis.
Formulation:
Kinetic energy of bumper before collision,
KE = ½ M*S2…………………….. (Equation 1)
Strain Energy of bumper after collision
SE = ½ σ2V/E ……………………….. (Equation 2)
Since the total kinetic energy of Bumper is
converted into strain energy of Bumper, so according to
law of conservation of energy, total Energy of the system is
constant. So, balancing energies of the Bumper.
KE = SE
i.e. ½ M*S2 = ½ σ2V/E …………….…………… (Equation 3)
From equation 3, we can find stress generated in Bumper.
So, Stress generated by bumper is given by,
σ2 = M*S2*E/ V
σ = √ (M* S2*E/ V)………………. (Equation 4)
σ = Kf* √ (M* S2*E/ V)……………. (Equation 5)
Where, Kf = Ks* Ksz * Kc * Ke.
Kf = Resultant Factors corresponding to shape, size, stress
concentration, and endurance limit as shown in following
table.
Table 5. Values of Design Stress Factors for Materials
Sha
pe
Fact
or
(Ks)
Size
Facto
r
(Ksz)
Stress
Concentrat
ion Factor
(Kc)
Endur
ance
Limit
Factor
(Ke)
Resulta
nt
Stress
Factor
(Kf)
ABS
Plastic
1 1 2.5 1 2.5
CFRP 1 1 1.1 1 1.1
GFRP 1 1 1.8 1 1.8
Now, Applying Material conditions for Bumper,
1] For ABS Plastic
Mass, M = 9.2672 Kg,
Velocity, S = 10 m/s,
Volume, V = 8.9108*10-3 m3,
Modulus of Elasticity, E = 2300*106 N/m2,
Resultant Stress Factor, Kf = 2.5
So, from equation 5,
σ = Kf* √ (M* S2*E/ V)……………. (Equation 5)
σ = 2.5* √ (9.2672 * 102*2300*106 / 8.9108*10-3)
σ = 38665229.86 N/m2,
σ = 38.66522986 MPa
2] CFRP
Mass, M = 16.039 Kg,
Velocity, S = 10 m/s,
Volume, V = 8.9108*10-3 m3,
Modulus of Elasticity, E = 3.5*1011 N/m2,
Resultant Stress Factor, Kf = 1.1
So, from equation 5,
σ = Kf* √ (M* S2*E/ V)……………. (Equation 5)
σ = 1.1 * √ (16.039 * 102*3.5*1011 / 8.9108*10-3)
σ = 276097808.8 N/m2,
σ = 276.0978088 MPa
3] GFRP
Mass, M = 10.693 Kg,
Velocity, S = 10 m/s,
Volume, V = 8.9108*10-3 m3,
Modulus of Elasticity, E = 60000*106 N/m2,
Resultant Stress Factor, Kf = 1.8
So, from equation 5,
σ = Kf* √ (M* S2*E/ V )…………….(Equation 5 )
σ = 1.8 * √ (10.693 * 102* 60000*106 / 8.9108*10-3)
σ = 152735350.41 N/m2,
σ = 152.73 MPa
Comparison of results for Numerical Impact Stress and
ANSYS Impact Stress –
Table 6. Comparison of results
Sr.
No.
Material
Numerical
Impact
Stress
ANSYS
Impact
Stress
Percentage
Error](https://image.slidesharecdn.com/irjet-v4i2160-171117093845/85/Design-of-automobile-front-bumper-for-collision-energy-Attenuation-5-320.jpg)
Design of automobile front bumper for collision energy Attenuation
- 1. INTERNATIONAL RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY (IRJET) E-ISSN: 2395 -0056 VOLUME: 04 ISSUE: 02 | FEB -2017 WWW.IRJET.NET P-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 819 DESIGN OF AUTOMOBILE FRONT BUMPER FOR COLLISION ENERGY ATTENUATION 1. Bharat P. Patil, 2. Prashant N. Ulhe 1. M. E. Student, Mechanical Dept. SSBT’s COET, Bambhori, Jalgaon, Maharashtra, India. 2. Assistant Professor, Mechanical Dept. SSBT’s COET, Bambhori, Jalgaon, Maharashtra, India. ------------------------------------------------------------------------***------------------------------------------------------------------------- Abstract – While designing the bumper in the automobile considering an impact during collision is important. The design must improve the ability to absorb more impact load, reducing stress, and increase the protection of the front car component. The method have been employed was study the front bumper system, design using CATIA software, and analyze the alternative front bumper material using ANSYS software. The aim of this work is to reduce the degree of damage to passengers, and vehicle’s body caused by vehicle collisions. Crash phenomena involving road vehicle were studied for the purpose of developing an impact attenuation design that can withstand specific speed. Key Words: front bumper;composites;collision;ANSYS. I. INTRODUCTION In an automobile's structure bumper is the front-most or rear-most part. It is used to sustain an impact and reduce or prevent damage to the passengers, vehicle's frame or safety systems of car during low speed collision. Generally steel and Aluminum has been the dominant material for vehicle body in old days. But, now a days the front of car bumper is made by composite that suit for the commercial front bumper (1). The bumper is use to cover the bumper beam that connected to the car’s frame. Even it could prevent a small damage for the car, the front bumper important as an aesthetical value. Composite are the best materials for bumper which are aesthetically pleasant, lighter weight and offer many more substantial advantages (2). II. PROBLEM STATEMENT Now a days accidents are frequent and cause damage to a vehicle’s body and became threat to human life. Hence crashworthiness of automobile bumper is essential. Also the cost for replacing bumper is quite expensive especially if surrounding area or part also damaged. Customer also blame to the manufacture that the bumper easily gets damaged although the collision was slow. The material of the bumper should be analyzed to find the alternative material that can improve the crashworthiness, also have toughness. III. LITERATURE SURVEY Until now many research and experiment has done on bumper design. Ramin Hosseinzadeh et al. [1] (2004), has studied on parametric research of automotive composite bumper beams subjected to low-velocity impacts and concluded that fuel efficiency and emission gas regulations are the main causes for reducing the weight of passengers’ cars by the use of composite material structures. Hence the composite will probably the best material to produce an effective bumper. As per Marzbanrad J. M. et.al [2] the important parameters considered for design and analysis of an automotive front bumper beam to improve the crashworthiness design in low-velocity impact are material, thickness, shape and impact condition. Gintautas Dundulis et al. [3], Static analytical and experimental research of shock absorber to safe guard the nuclear fuel assemblies. Ping Yang et al. [4], Design, test and modeling evaluation approach of a novel Si-oil shock absorber for protection of electronic equipment in moving vehicles. In their study M. M. Davoodi et al. [5] studied on conceptual design of polymer composite automotive bumper energy absorber. It was observed that, major injury due to impact velocity of around 20-30 km/h was affected to the knee ligament. They proposed fiber reinforced epoxy composite material for bumper as a pedestrian energy absorber. The energy absorption capacity was sufficient for pedestrian impact and it could possible to use as substitute for the existing materials for low impact collision. IV. SOLID MODELING A solid model is better because for an object it provides more complete representation than its surface model. It provides more topological information in addition to the geometrical information which helps to represent the solid unambiguously. There are different software that are used for generating these solid models like CATIA and Pro-E. In this project the frame is modeled by using CATIA V5. All the parts that are required for constructing the frame are modeled in part module by using different commands like extrude, loft, fillet, shell etc. as shown in Fig. 1.
- 2. INTERNATIONAL RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY (IRJET) E-ISSN: 2395 -0056 VOLUME: 04 ISSUE: 02 | FEB -2017 WWW.IRJET.NET P-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 820 Figure - 1: Modeling of components in CATIA V5 V. IMPACT ANALYSIS OF BUMPER A. Organization Of The Ansys Program For analysis of bumper we are using ANSYS software. The begin level acts as a gateway in to and out of the ANSYS program. It is also used for certain global program controls such as changing the job name, clearing (zeroing out) the database, and copying binary files. When we first enter the program, we are at the begin level. At the processor level, several processors are available; each processor is a set of functions that perform a specific analysis task. For example, the general preprocessor is where we build the model, the solution processor is where we apply loads and obtain the solution, and the general postprocessor is where we evaluate the results and obtain the solution. An additional post processor enables us to evaluate solution results at specific points in the model as a function of time. B. Performing typical ANSYS Analysis The ANSYS program has many finite element analysis capabilities, ranging from a simple, linear, static analysis to a complex, nonlinear, dynamic analysis. In this project we have done dynamic analysis of bumper, using bumper model designed in CATIA software. The analysis guide manuals in the ANSYS documentation set describe specific procedures for performing analysis for different engineering disciplines. A typical ANSYS analysis has three distinct steps: The following table shows the brief description of steps followed in each phase. Table - 1. Steps in ANSYS analysis PRE-PROCESSOR SOLUTION PROCESSOR POST-PROCESSOR Assigning element type Analysis definition Read results Geometry definition Constant definition Plot results on graphs Assigning real constants Load definition View animated results Material definition Solve Mesh generation Model display The solid model is used in ANSYS software to simulate impact analysis as shown in fig. 2. It is considered that bumper is striking against fixed support. E.g. Pole. At a velocity of 10 m/s. Figure - 2: Simulation of Impact phenomenon in ANSYS In this way impact analysis of bumper has been done using following materials. D. Material properties The suitable materials are selected on the basis of previous research data which are as follows. Table - 2. ABS Plastic Material Properties Young's Modulus MPa Poisson's Ratio Bulk Modulus MPa Shear Modulus MPa Density 2300 0.33 1916.7 884.62 1040 Kg/m^3
- 3. INTERNATIONAL RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY (IRJET) E-ISSN: 2395 -0056 VOLUME: 04 ISSUE: 02 | FEB -2017 WWW.IRJET.NET P-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 821 Table - 3. Carbon fiber reinforced Plastic Material Properties Young's Modulus MPa Poisson's Ratio Bulk Modulus MPa Shear Modulus MPa Density 350000 0.3 291670 134620 1800 kg/m^3 Table - 4. Glass fiber reinforced Plastic Material Properties Young's Modulus MPa Poisson's Ratio Bulk Modulus MPa Shear Modulus MPa Density 60000 0.3 50000 23077 1200 kg/m^3 VI. RESULTS After doing Impact analysis of bumper in ANSYS software we got following results – A. ANSYS Results for ABS Plastic Considering Bumper material as Acrylonitrile Butadiene Styrene Plastic (ABS Plastic) and pole material as Structural Steel as shown in Fig. 3 Equivalent stress in ABS Plastic Maximum Equivalent stress = 39.18 MPa Figure - 3: Equivalent Stress Distribution in ABS Plastic Deformation in ABS Plastic Maximum Total Deformation = 38.158 mm Figure - 4: Deformation in ABS Plastic B. ANSYS Results for carbon fiber reinforced composites Considering Bumper material as Carbon fiber reinforced composite and pole material as Structural Steel as shown in Fig. 5 Equivalent stress in Carbon fiber reinforced Plastic Maximum Equivalent stress = 256.21 MPa Figure - 5: Equivalent Stress Distribution in Carbon fiber reinforced Plastic
- 4. INTERNATIONAL RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY (IRJET) E-ISSN: 2395 -0056 VOLUME: 04 ISSUE: 02 | FEB -2017 WWW.IRJET.NET P-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 822 Deformation in Carbon fiber reinforced Plastic Maximum Total Deformation = 24.842 mm Figure - 6: Deformation in Bumper with Carbon fiber reinforced Plastic C. ANSYS Results for Glass fiber reinforced Plastic Considering Bumper material as Glass fiber reinforced composite and pole material as Structural Steel as shown in Fig. 7 Equivalent stress in Glass fiber reinforced Plastic Maximum Equivalent stress = 152.4 MPa Figure -7: Equivalent Stress Distribution in Glass fiber reinforced Plastic Deformation in Glass fiber reinforced Plastic Maximum Total Deformation = 22.514 mm Figure - 8: Deformation in Bumper with Glass fiber reinforced Plastic. D. Mathematical modeling and Results Parameters: Let, M = Mass of Bumper in Kg, S = Velocity of Bumper in m/s, V = Volume of Bumper in m3, E = Modulus of Elasticity of Bumper in N/m2, σ = Stress generated in Bumper in N/m2, KE = Change in Kinetic Energy of Bumper in J, SE = Change in Strain Energy of Bumper in J, Assumptions Made: 1) The collision is perfectly elastic so that Momentum is conserved. 2) The system is loaded within elastic limit to apply theories of failure. 3) The time for collision is very less, that stresses generated rapidly and distribute in fraction of second. 4) The whole kinetic energy of Bumper is converted into strain energy of Bumper only. 5) The friction between Pole and Bumper is neglected.
- 5. INTERNATIONAL RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY (IRJET) E-ISSN: 2395 -0056 VOLUME: 04 ISSUE: 02 | FEB -2017 WWW.IRJET.NET P-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 823 6) Neglecting effect of bending and shearing of Pole and Bumper for analysis. Formulation: Kinetic energy of bumper before collision, KE = ½ M*S2…………………….. (Equation 1) Strain Energy of bumper after collision SE = ½ σ2V/E ……………………….. (Equation 2) Since the total kinetic energy of Bumper is converted into strain energy of Bumper, so according to law of conservation of energy, total Energy of the system is constant. So, balancing energies of the Bumper. KE = SE i.e. ½ M*S2 = ½ σ2V/E …………….…………… (Equation 3) From equation 3, we can find stress generated in Bumper. So, Stress generated by bumper is given by, σ2 = M*S2*E/ V σ = √ (M* S2*E/ V)………………. (Equation 4) σ = Kf* √ (M* S2*E/ V)……………. (Equation 5) Where, Kf = Ks* Ksz * Kc * Ke. Kf = Resultant Factors corresponding to shape, size, stress concentration, and endurance limit as shown in following table. Table 5. Values of Design Stress Factors for Materials Sha pe Fact or (Ks) Size Facto r (Ksz) Stress Concentrat ion Factor (Kc) Endur ance Limit Factor (Ke) Resulta nt Stress Factor (Kf) ABS Plastic 1 1 2.5 1 2.5 CFRP 1 1 1.1 1 1.1 GFRP 1 1 1.8 1 1.8 Now, Applying Material conditions for Bumper, 1] For ABS Plastic Mass, M = 9.2672 Kg, Velocity, S = 10 m/s, Volume, V = 8.9108*10-3 m3, Modulus of Elasticity, E = 2300*106 N/m2, Resultant Stress Factor, Kf = 2.5 So, from equation 5, σ = Kf* √ (M* S2*E/ V)……………. (Equation 5) σ = 2.5* √ (9.2672 * 102*2300*106 / 8.9108*10-3) σ = 38665229.86 N/m2, σ = 38.66522986 MPa 2] CFRP Mass, M = 16.039 Kg, Velocity, S = 10 m/s, Volume, V = 8.9108*10-3 m3, Modulus of Elasticity, E = 3.5*1011 N/m2, Resultant Stress Factor, Kf = 1.1 So, from equation 5, σ = Kf* √ (M* S2*E/ V)……………. (Equation 5) σ = 1.1 * √ (16.039 * 102*3.5*1011 / 8.9108*10-3) σ = 276097808.8 N/m2, σ = 276.0978088 MPa 3] GFRP Mass, M = 10.693 Kg, Velocity, S = 10 m/s, Volume, V = 8.9108*10-3 m3, Modulus of Elasticity, E = 60000*106 N/m2, Resultant Stress Factor, Kf = 1.8 So, from equation 5, σ = Kf* √ (M* S2*E/ V )…………….(Equation 5 ) σ = 1.8 * √ (10.693 * 102* 60000*106 / 8.9108*10-3) σ = 152735350.41 N/m2, σ = 152.73 MPa Comparison of results for Numerical Impact Stress and ANSYS Impact Stress – Table 6. Comparison of results Sr. No. Material Numerical Impact Stress ANSYS Impact Stress Percentage Error
- 6. INTERNATIONAL RESEARCH JOURNAL OF ENGINEERING AND TECHNOLOGY (IRJET) E-ISSN: 2395 -0056 VOLUME: 04 ISSUE: 02 | FEB -2017 WWW.IRJET.NET P-ISSN: 2395-0072 © 2017, IRJET | Impact Factor value: 5.181 | ISO 9001:2008 Certified Journal | Page 824 1 ABS Plastic 38.6652 39.18 -1.3313 2 CFRP 276.0978 256.21 7.2031 3 GFRP 152.7350 152.40 0.2193 From above table we can say that ANSYS results are confirming to mathematical model and maximum error is +7.2%. VII. CONCLUSION From this report it can be concluded that computer model can be used to predict impact analysis of bumper and stress pattern within bumper system has been studied. Also mathematical model results provides validation for ANSYS simulation model results. Depending on outcome, composite materials for bumper are selected for impact strength analysis. From, impact analysis of bumper it is suggested that Glass fiber reinforced composite bumper is suitable from repairing cost point of view, because it has minimum deformation. But Acrylonitrile Butadiene Styrene Plastic (ABS Plastic) is having minimum stress, hence it is best material from impact point of view and can absorb maximum collision energy. VIII. ACKNOWLEDGMENT The authors expresses their deepest gratitude to Department of Mechanical Engineering of SSBT’s COET, Bambhori, Jalgaon, for providing their valuable time and full-fledged support to accomplish this research work. REFERENCES 1. Hosseinzadeh RM, Shokrieh M, and Lessard LB, “Parametric study on automotive composite bumper beams subjected to low-velocity impacts”, 2005. 2. Marzbanrad JM, Alijanpour M, and Kiasat MS, “Design and analysis of automotive bumper beam in low speed frontal crashesh”, Thin Walled Struct., P P 902-911, 2009. 3. Gintautas Dundulis et al, Static analytical and experimental research of shock absorber to safe guard the nuclear fuel assemblies. Elsevier, Nuclear engineering and design, 239, 2009, 1-8. 4. Ping Yang et al, Design, test and modeling evaluation approach of a novel Si-oil shock absorber for protection of electronic equipment in moving vehicles. Mechanism and Machine Theory, 43, 2008, 18–32. 5. M. M. Davoodi, S. M. Sapuan and R. Yunus “Conceptual design of polymer composite Automotive bumper energy absorber” (2007).