Traction and Stiffness Flashcards

0
Q

What effect does traction have on center of mass?

A

Sideways force T.r

Rotating action or moment T.r * h

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1
Q

What is the cornering efficiency?

A

The loss of relative traction.

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2
Q

Describe the change in weight distribution when going round a corner.

A

Vertical load on the outside corner increases

Vertical load on the inside corn decreases.

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3
Q

In what ways can car designers increase traction.

A

Keep all tires on the ground at all times by ensuring as even a load distribution as possible.

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4
Q

How does body stiffness affect the vehicle?

A

Keeps the tires on the ground at all times

Ensures weight distribution during cornering

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5
Q

What are the two most important types of loading?

A

Bending

Tortion

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6
Q

Why might bending occur on the body?

A

Weight of the passengers, engine (static load)

Dynamic effects when driving over imperfections in the road

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7
Q

What is the job of the beam?

A

To transfer applied loads to the foundations without deflecting too much.

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8
Q

How is a shear load applied?

A

Zig-zag pattern

Half the load is applies to each support

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9
Q

What force would cause a beam to bend?

A

Shear load
Tension at the bottom, compression at the top
Fd

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10
Q

Describe the engineer’s theory of bending?

A

Internal bending forces vary linearly.
Maximum tensile force on only one surface.
Zero force at the neutral surface
Maximum compressive force on the other surface.

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11
Q

How is the new iBeam better?

A

Makes more use of neutral surface.

Resistance to bending by the flanges (top & bottom)

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12
Q

Give some examples of beam section shapes.

A
Z
I
C (or channel)
Solid rectangles or circles
Hollow rectangles or circles
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13
Q

Describe the beam stiffness equations?

A

M=k.b*theta

K.b=E*I

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14
Q

How can bending stiffness be enhanced?

A

Change the material
Change the geometry
Increase the depth

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15
Q

What is the second moment of inertia?

A

Rotational weight.

Shows how the material is distributed about the neutral axis.

16
Q

Give an example of different beam stiffnesses (try 2/3)

A

Citroen 5CV Torpedo:
Low power, low weight
Light chassis
Shallow beam sections

Delorean DMC-12:
Heavy construction
Deep beam thickness
Besm intrudes into the car

Lotus Elan:
Thin sheet, light structure
Deep beam
Weight minimised by cutting holes

17
Q

How can sheet metal be strengthened?

A

Corrugating
Folding
Attaching stiffners/ribs

18
Q

What is tortional stiffness?

A

Ability of the body to resist twisting.

19
Q

What are the disadvantages of a low tortional stiffness?

A

Noisy and uncomfortable ride
Possible loss of tyre contact with the ground
^this mean loss of traction