flow behaviour analysis inside a helmet

Flow Behaviour Analysis Inside A Helmet

Abhishek Pushkar1, Kunal Mehra2, Sahil Verma3, Chanakya Rajan4

UG Student1,2,3,4, Department of Mechanical Engineering, JIMS Engineering Management Technical Campus,

Greater Noida, Uttar Pradesh, India.

Ashutosh Singh5, Dhruv Kumar6

Assistant Professor5,6, Department of Mechanical Engineering, JIMS Engineering Management Technical Campus,

Greater Noida, Uttar Pradesh, India.

Devendra Jha7

Professor7, Department of Mechanical Engineering, JIMS Engineering Management Technical Campus,

Greater Noida, Uttar Pradesh, India

Abstract

A helmet is a defensive object used by riders for head

protection against injuries caused by road accidents. In this

paper, a standard helmet is designed using SolidWorks 2018.

The parametric based analysis is performed on the helmet

using SolidWorks Flow Simulation Tool. Parameters like

shear stress, vorticity, velocity, pressure, acoustic power and

temperature are assessed. Measured values obtained are

utilized to survey the defensive execution of the helmet.

Through the results, a comfortable as well as

protective structure of helmet can be planned and designed.

Keywords: Helmet, Shear stress, Flow Simulation, Vorticity,

Velocity, Temperature, Pressure.

Introduction In today’s world, the most common mode of transportation is

two-wheelers. We can find one in nearly every household

nowadays. Besides this, it is also used in Racing as a sport.

Head injuries as a consequence of road accidents are one of

the main reasons of death and disability among people. A

helmet decreases this danger of head and cerebrum wounds by

diminishing the effect of impact to the head.

During an impact, helmet works in a three-step mechanism:

1. It decreases the deceleration of the skull, and

consequently the cerebrum development, by directly

dealing with the effect. The delicate material

consolidated in the helmet assimilates a portion of the

effect and consequently, the head stops all the more

gradually. This implies the cerebrum does not hit the

skull with such extraordinary power. 2. It spreads the powers of the effect over a more

noteworthy surface zone with the goal that they are not

focused on specific territories of the skull. 3. It counteracts direct contact between the skull and the

affecting item by going about as a mechanical

boundary between the head and the article.

Figure 1: Parts of a helmet

In addition to meeting the antecedently delineated functions

and conforming to standards, a helmet must be designed to

suit the native weather and traffic conditions. The subsequent

unit covers few aspects typically addressed by helmet

designers:

1. Materials utilized in the development of a helmet

should not deteriorate due to weather change, should not

be harmful or cause hypersensitive responses and should

have a good life. Right now, the plastic materials regularly

used are Expanded Poly-Styrene (EPS), Acrylonitrile

Butadiene Styrene (ABS), Poly Carbon (PC) and Poly

Propylene (PP). While the material of the cap shell, for the

most part, contains PC, PVC, ABS or Fiberglass; the

crushable liner inside the shell is frequently made out of

EPS – a material that can assimilate stun and sway and is

generally economical. However, helmets with EPS liners

are required to be disposed off after an accident, and

International Journal of Applied Engineering Research ISSN 0973-4562 Volume 14, Number 10, 2019 (Special Issue) © Research India Publications. http://www.ripublication.com

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regardless of this, clients need to replace such helmets

after 3-5 years of usage.

2. Gauges regularly set the base inclusion of a helmet.

Half-head helmet offers negligible inclusion. Full-

face helmet guarantees that the wearer's fringe vision

and hearing are not traded off.

Literature Review

S.K. Biswal, S.M. Shahrukh Rais, K. Krishna considered

two materials – Acrylonitrile Butadiene Styrene (ABS) and

Poly Vinyl Chloride (PVC) for dynamic analysis of helmet.

They designed the helmet using CATIA V5.0 and did the

Impact test analysis using ANSYS software. They compared

Von Misses Stresses, Strain and Deformations of ABS and

PVC at 50, 60 & 70 km/h in front, right and back directions.

They concluded that PVC plastic material is better than ABS

in terms of stresses developed. So, if the shell part is made

using PVC, then it would be able to withstand large stresses.

However, ABS material is preferred over PVC to provide

lesser deformations during accidents.

V.C. Sathish Gandhi, R. Kumaravelan, S. Ramesh, M.

Venkatesan, M. Ponraj carried out the investigation of

Motor Cycle Helmet under Static and Dynamic Loading. The

Design and Investigation of head protector were done in

ANSYS software for both static and dynamic conditions.

S. Irfan Sadaq, Md. Abdul Raheem Junaidi, V. Suvarna

Kumar, Joseph George, Konnully,

Sirajuddin Qadiri completed Impact Test on Motor Cycle

Helmet for Different Impact edges using FEA. A limited

component demonstration depending on practical geometric

highlight of a bike helmet was set up, and a component,

COSMOS, was used to reproduce dynamic reactions at

various effect speeds.

V.C. Sathish Gandhi, R. Kumaravelan, S. Ramesh, M.

Venkatesan, M. Siva Rama Krishnan designed a helmet

using the concept of streamline shape with antiglare visor. In

this paper, they concluded that, for reducing the neck pain of a

rider after long traveling, we should use streamlined shape

helmet. Whereas, the polymer coated visor reduces the glare

and eliminates the opposite headlight glare during night

ridings in a better way as compared to the noncoated visor.

P. Viswanadha Raju, Vinod Banthia, Abdul Nassar,

Designed a Streamlined Motorcycle Helmet with Enhanced

Head Protection. Fluid stream investigations were completed

to review the stream conduct inside a helmet and alterations

were proposed to improve the stream inside the helmet to

provide more comfort to the rider. Effect examination was

done to check if the adjusted cap meets the BIS sway retention

test particular.

Methodology

The entire model was designed in Dassault systems

Solidworks, and the analysis was done in Solidworks Fluid

Simulation. The process of designing involved various

degrees of surface and solid modeling. Most important of

which included the freeform surface modeling tools which

were used to give the curvature and shape of the design. The

design utilizes the dimensions specified in the following

diagram.

Figure 2: 2D Drawing of the Helmet with Different Views

and Dimensions

Furthermore, as the helmet is subjected to various flow

simulations as in the case of it being used, it has to be

subjected to the flow of air. The flow of air is limited to a

speed of 100Km/hr since this is the most common and the

most frequent speed at which it is used. Both steady state and

transient analysis were carried out.

Figure 3: 3D Model of the helmet

Figure 4: Computational Domain


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Results and Discussions

From our simulation, the following results were observed in

the model :

Figure 5: Flow Trajectories

From Fig. 5, we can see the various flow trajectories of the air

flow. As observed, we can see a small amount of air is

forming a vortex feature at two points i.e. inside and behind

the flow model. This called for further vorticity analysis

which is discussed further in the project.

Figure 6(a): Side View Velocity

Figure 6(b): Top View Velocity

Figure 6(c): Front View Velocity

Fig 6(a, b, c), represents the flow speeds in different axes. The

maximum and minimum speed of flow for side, top and front

view are (36.857 m/s, 1.204 m/s), (33.023 m/s, 1.215 m/s) and

(37.153 m/s, 1.216 m/s) as shown in the figure respectively.

Figure 7: Temperature

Fig. 7, represents the various temperature regions developed

as a result of flow alone. It was observed that the internal

regions were heated by a certain temperature. Also, it was

noteworthy to note there are also certain regions where the

temperature is reduced. The maximum and minimum values

of temperature are 20.42 0C, and 19.75 0C respectively.

Fig. 8, represents the various regions of acoustic effects

created i.e. the maximum noise regions and their region of

effect. The entire effect created is because of flow only. The

maximum and minimum values are 0 dB and 49.53 dB.


Page 157 of 159

Figure 8: Acoustic Power

Fig. 9 represents the various shear stress regions and their

distribution on the surface of the helmet in various views. The

maximum i.e. 3.09 Pa and minimum i.e. 0.09 Pa regions of

shear stresses are seen from the image. The frontal region has

the maximum interaction with air and thus suffers from

maximum shear effects.

Figure 9: Shear Stress Analysis At Different Face Of Helmet

(Front, Back, Right, Isometric, Top & Bottom)

The group of pictures shown below i.e. Fig. 10 (A, B, C, D, E,

F, G) represents the vorticity and Table 1 represents the

maximum and minimum vorticity of the flow in rotations per

seconds at different positions.

Figure 10: Vorticity side view

(A) INITIALLY (B) JUST BEFORE CONTACT

(C) DUAL VORTEX (D) MAXIMUM CONTACT

(E) POST CONTACT (F) VORTEX SUBSIDING


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Positions

Maximum

Vorticity

(1/s)

Minimum

Vorticity

(1/s)

Initial 11.25 1.30

Just Before Contact 125.17 0.97

Dual Vortex 108.78 0.76

Maximum Contact 419.46 0.86

Post Contact 225.53 1.20

Vortex Subsiding 73.66 0.77

Table 1: Maximum & Minimum Vorticity

Fig.11 represents the various pressure regions and their

distribution on the surface of the helmet in various views. The

maximum i.e. 1.09 atm and minimum i.e. 0.99 atm regions of

pressure are front and side of the helmet respectively as

shown in the image. The frontal region has the maximum

interaction with air and thus suffers from maximum pressure

force. There is some weight also applied on the due helmet

mass and gravity which is under consideration for the

analysis.

Figure 11: Pressure Contours at different faces of helmet

(Front, Back, Left, Isometric, Top & Bottom)

Conclusion

Fluid flow Analyses were carried out in SolidWorks to study

the flow behavior inside a helmet and results were discussed

to improve the flow within the helmet to improve the comfort

of the rider. The following points were concluded: -

Vortices generated in the region between chin guard

and face due to insufficient air flow which results in

exhaled air recirculation, which may cause discomfort

to the rider. This can be improved by proper ventilation

at the front side.

The maximum and minimum speed of flow for side,

top and front view are (36.857 m/s, 1.204 m/s), (33.023

m/s, 1.215 m/s) and (37.153 m/s, 1.216 m/s)

respectively.

The temperature variation in the helmet was too small.

Similarly, noise creation inside the helmet was not so

problematic.

When we talk about shear stress and pressure force

then we see that the frontal region has the maximum

interaction with air and thus suffers from maximum

shear effects as well as maximum pressure force.

References [1] S.K. Sharma “ Objective Zoology ” 19th edition 2008 p.p

3.291-3.293

[2] B D Chaurasia “ Human Anatomy, vol-3 Head And Neck Brain ” 5th edition 2010, p.p 3-49.

[3] Gandhi, V.S., Kumaravelan, R., Ramesh, S., Venkatesan, M. and Ponraj, M.R., 2014. Performance Analysis of Motor Cycle Helmet under Static and Dynamic Loading. Mechanics and Mechanical Engineering, 18(2), pp.85-96.

[4] Raju, P.V., Vinod, B. and Abdul, N., 2009. Design of streamlined motorcycle helmet with enhanced head protection. SASTech J, 8(2), pp.1-8.

[5] Sadaq, S.I., Junaidi, A.R., Kumar, V.S., Konnully, J.G. and Qadiri, S.S., Impact Test on Motor Cycle Helmet for Different Impact angles using FEA. International Journal of Engineering Trends and Technology.[Online], 12(6), pp.278-281.

[6] Gandhi, V.S., Kumaravelan, R., Ramesh, S., Venkatesan, M. and Krishnan, M.S.R., 2014. An Aerodynamic Design and Analysis of Motor Cycle Helmet with Anti-Glare Visor. World Academy of Science, Engineering and Technology, International Journal of Mechanical, Aerospace, Industrial, Mechatronic and Manufacturing Engineering, 8(3), pp.628-631.

[7] Saroj Kumar Biswal, S.M.Shahrukh Rais, Karanamkrishna,2016, Impact test analysis on a 2-wheeler helmet using 3D modeling and analyzing software for two different materials. International Journal of innovative research in technology, pp. 249-253.

[8] Google Image https://www.bestbeginnermotorcycles.com/ultimate-motorcycle-helmet-guide/helmet-protective-diagram/

[9] Mills, N.J. and Gilchrist, A., 2008. Finite-element analysis of bicycle helmet oblique impacts. International Journal of Impact Engineering, 35(9), pp.1087-1101.

[10] Chang, L.T., Chang, G.L., Huang, J.Z., Huang, S.C., Liu, D.S. and Chang, C.H., 2003. Finite element analysis of the effect of motorcycle helmet materials against impact velocity. Journal of the Chinese Institute of Engineers, 26(6), pp.835-843.


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flow behaviour analysis inside a helmet

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