**6.2 Calculations of stress and failure**

Forces on a wheelchair casters and wheels, when the assumption is that the operator weighs 100 kg (**Figures 9–12**) (Eqs. (1)–(3)).

$$\text{Considering:}\,\text{Fperson} = \text{Fp} = \text{981N} \text{ (100 kg)}\tag{1}$$

$$Lcaster = Lc = \text{\textquotedbl{}15.81 \, mm} \tag{2}$$

$$\text{Ltotal} = \text{Lc} + \text{Lw} = \text{448.11 mm} \tag{3}$$

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*Development of a Rough Terrain Wheelchair Design DOI: http://dx.doi.org/10.5772/intechopen.91267*

**Figure 10.** *Ratchet set up [13].*

**Figure 11.**

**Figure 12.**

*Bending moment diagram [13].*

*Shear force diagram on the ratchet lever [13].*

**6.3 Internal moments and forces in a wheelchair axle**

for the axle to take note of the critical points.

**6.4 Bending stress in a wheelchair axle**

The forces and moments acting on the back hub of a wheelchair were determined a similar path as above. The greatest moment exits where the hub is welded to the frame. There are vertical forces applied on the wheel starting from the ground, there likewise might be horizontal forces that act on the wheel when the wheelchair tips over, these forces cause moments on the axle. Von Mises stresses were analyzed

At the point when a section is twisted the applied moment creates stresses in the material. On one side of the part the material is extended and in this way has tensile

The findings are that each rear wheel will take a weight force of 345 N. While the caster wheel takes 144.815 N.

**Figure 9.** *Force analysis [3, 13].*

**Figure 11.** *Shear force diagram on the ratchet lever [13].*

*Public Health in Developing Countries - Challenges and Opportunities*

of composite bodies this was considered in the detailed design.

operator weighs 100 kg (**Figures 9–12**) (Eqs. (1)–(3)).

**6.2 Calculations of stress and failure**

caster wheel takes 144.815 N.

The center of gravity (CG) is the focal point of a body's weight appropriation, where the force of gravity can be considered to act. It is the point in any object about which it is in perfect balance regardless of how it is turned or pivoted around that point. For a limited arrangement of point masses, CG might be characterized as the normal of positions weighted by mass. For its figuring a few parameters were viewed as, for example, the thickness of the material, the volume of the piece and the good ways from the origin arrange around the focal point of the piece. This is critical for the stability of the wheel chair. Thus considering x, y and z axis the center of gravity of the point masses will be given, and to find the center of gravity

Forces on a wheelchair casters and wheels, when the assumption is that the

*Lcaster* = *Lc* = 315.81 *mm* (2)

*Ltotal* = *Lc* + *Lw* = 448.11 *mm* (3)

The findings are that each rear wheel will take a weight force of 345 N. While the

Considering: *Fperson* = *Fp* = 981*N* (100 *kg*) (1)

**6.1 Center of gravity**

**166**

**Figure 9.**

*Force analysis [3, 13].*
