Analysis of Non-Pneumatic Tyre

. Mostly pneumatic tyres are used for fast moving vehicle and solid tyres are used in less load carrying slow moving vehicle. Conventional tyres are manufactured using materials like rubber, EVA plastic, etc. Based on the load carrying components of the frame body the number of tyres and the material of the tyre is decided for motion possibility and stability of the body. In this project we are going to analyze the non-pneumatic wheelchair tyre. The strength variation is analyzed by comparing existing tyre and non-pneumatic tyre pattern. And comparison is done for modification of existing design for improving properties like strength and durability.


Introduction to Non-Pneumatic Tyre
The tyre is a vehicle component which is used to have moving motion of the body based on the direction of rotation.The tyre has a line contact with the surface of ground and body to have minimal friction and move the body in motion, the tyre is load carrying component and force output in form of moment.The tyres are used in major applications, such as those for automobiles, bicycles, wheelchair and other applications provide traction between the vehicle and the ground surface.
Non-Pneumatic Tyre were developed which overcome the disadvantages of pneumatic tyre.When the non-pneumatic tyre is subjected to usual ground surface, the solid thick section tyre absorbs ground impacts, in the pneumatic tyre in the pressurized air does the same [2].Non-Pneumatic Tyre has the disadvantage of increase in weight which can be reduced by considering optimized pattern based on different structures.

Literature Review
Aravind Mohan et al. [1], performed analysis of non-pneumatic honeycomb structure tyres with same cell wall thickness and different angle, length, heights.Honeycomb spoke with larger cell angle showed minimum stress concentration and exhibit least stress, maximum deflection and minimum contact pressure and performance best under static condition.
Umesh G C et al. [2], examined hexagonal structure pattern designed for non-pneumatic tyre by applying uni-axial load.The spokes experience tension as well as compression while they are rolling.So, spokes required to have stiffness and rigidity.Hexagonal structure pattern is established to be superior in terms of fatigue resistance and durability.
Nimkar et al. [3], performed analysis on existing tires and compared with Non-Pneumatic Tyre.The stresses observed by the Non-Pneumatic Tyre are comparatively more but it has advantage of absorption of flexural load.
Sarma S R et al. [4], conformed tubeless tyre is better than tube tyre.The tube tyre and tubeless tyre is examined for different cases and the results observed is tubeless tyre has more benefits than tube tyre.
Lopes D et al. [5], compared the material strength of EVA plastic and rubber material.The rubber material has better strength and capability of the impact load stress absorption strength.
Ali M et al. [6], examined elastic deformations in tyre patterns of different structures and materials.The models are analysed for static conditions and based-on deformation of the honey comb structure with rubber material has high flexure and Tensile strength.
Routhier F et al. [7] analysed for different loads on wheel chair tyre.The tyre is analysed for rolling moment and fixing the joints, the critical section is analysed.The wheelchair tyre is analysed to different mass loads of 50Kg-123Kg, and tyre strength is analysed.
Kabakçi G C et al. [8] mechanical properties of rubber and reinforced rubber material are analysed using flexural loads and the results observed are reinforced rubber has less variation and also mass of the product can be reduced.

Tyre Modelling and Analyzation of the Pattern with Existing Condition
The wheelchair rear wheel is modelled as shown in Fig. 1(a) based on the Entros SC809B wheelchair model [3], which is designed based on the ISO 7176-8 standards.Wheelchair wheel tube is analysed to torque load of 15000Nmm i.e. 50N force for tyre of radius 300mm [7] in static condition as shown in Fig. 1  The wheelchair wheel has many parts, but major unusual surface vibrations needed to be reduce for the application and the tyre is used to reduce the flexural loads.So, it is analysed for different conditions.

Analysis of different type tyres
The different types of tyres are tube tyre, tubeless tyre, full solid tyre and different pattern material tyres.As tyre is symmetrical component, so 600sector analyzation results can be followed for analysis [4].The tube tyre, tubeless tyre and full material tyre are modelled as shown in Fig. 2. The modelled tyre is analysed for rubber material condition and the static load of force 1000N (i.e.100kg force applied) and 15000Nmm is applied based on the application [7] as shown in Fig. 3.For wheelchair application tube tyre compressed air pressure is applied 0.0689476MPa (i.e.15psi pressure) in Fig. 3   Table 1 indicates type of tyre vs stress for rubber material.It is observed that full material tyre has more strength when compared with tube and tubeless tyre, but it has disadvantage of more weight.Table 1.Type of tyre vs stress for rubber material.

Analysis of tyre for different materials
The full material 600sector tyre is analysed using materials EVA plastic, rubber and reinforced rubber [5][8].The loads are applied [7] as shown in Fig. 3(a).Table 2 indicates tyre of different material vs stress for full material tyre.It is observed that rubber tyre has more strength when compared with EVA plastic and reinforced rubber, but it has disadvantage of more weight and cost.So reinforced rubber material is preferred for less mass and better strength when compared with EVA plastic.Reinforced rubber 90.81

Analysis of tyre for different pattern
The 600 sector reinforced rubber tyre of full material is compared with hexagonal reduction pattern and circular reduction pattern.The parameters analysed for reduction of hexagonal pattern with variable hexagon dimension (width) and constant spacing of the pattern is 15mm and parameters analysed for reduction of circular pattern with variable circular dimension (diameter) and constant spacing of the pattern is 15 mm.The reduced hexagonal pattern with variable hexagon dimension is shown in Fig.

Results & Conclusion
The existing tires are different type's tube tyre, tubeless tyre, full material tyre and different pattern material tyres.The tube tyre, tubeless tyre and full material tyre are analysed based on static load application for rubber material.It is observed that full material tyre has more strength when compared with tube and tubeless tyre, but it has disadvantage of more weight.The wheelchair tyre is analysed for EVA plastic, rubber and reinforced rubber materials.It is observed that rubber tyre has more strength when compared with EVA plastic and reinforced rubber, but it has disadvantage of more weight and cost.So reinforced rubber material is preferred for less mass and better strength when compared with EVA plastic.The reinforced rubber tyre of full material is compared with hexagonal reduction pattern with variable hexagon dimension and circular reduction pattern with variable circular dimension.
It is observed that hexagonal reduction pattern has optimal stress when compared with circular reduction pattern.Mostly hexagonal pattern is recommended for easy manufacturing and better product quality.
(b) to observe the stress concentration location shown in Fig. 1(c) &1(d).Wheelchair wheel is subjected to torsional load condition to check the failure condition of the rotation.

Figure 1 .
Figure 1.(a) Front view of wheelchair rear tyre (b) Torsional load applied on wheelchair tyre (c) Stress observed on wheelchair tyre (d) Critical location of the wheelchair tyre.

Figure 2 .
Figure 2. (a) Isometric view of full solid tyre (b) Isometric view of tube tyre (c) Isometric view of tubeless tyre.

Figure 3 .
Figure 3. (a) Load applied on full solid tyre (b) Load applied on tube tyre (c) Load applied on tubeless tyre.

Figure 4 .
Figure 4. a) Hexagonal reduction pattern tyre of width variable hexagon dimension b) Circular reduction pattern tyre of diameter variable circular dimension /doi.org/10.1051/e3sconf/202343001274274 430 The patterned non-pneumatic tyres are advantageous to rough terrain surface.

Table 2 .
Tyre of different material vs stress for full material tyre S. No.

Table 3
indicates type of tyre pattern vs stress for reinforced rubber material.It is observed that hexagonal reduction pattern with variable hexagon dimension has optimal stress when compared with circular reduction pattern with variable circular dimension.But it varies with the dimension and spacing of the pattern as shown in Graph 1. Mostly hexagonal pattern is recommended for easy manufacturing and better product quality.

Table 3 .
Type of tyre pattern vs stress for reinforced rubber material Mass of the tyre Vs Stress obtained for variable dimension