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Sammanfattning

SAAB Automobile AB

is a car manufacturer within General Motors corporate group. SAAB

Automobile AB

has a big part of the responsibility for the brake development in the corporate

group. The car industry is facing harder environmental requirements, which influence the brake

development. The focus is to develop brakes with low drag and sustained brake feeling and

performance. Important characters for the brake caliper are high stiffness and low weight, high

stiffness results in high performance and low weight is important because it is unsprung mass.

This thesis investigates the possibility to improve the performance of the brake caliper for a

GM

project. The aim is to design a caliper with less amount of material but with the same stiffness.

The delimitations are that the manufacturing costs should be unchanged and the design should

work without modifications of the surrounding parts.

Computer aided design models (CAD- models) are built in

Solid Edge, which are evaluated with

finite element analysis (FEA) in

Ansys Workbench. An organized design of experiments is used

to find the optimal geometry of the caliper. A free form fabrication model of the concept is built

which are used as a probe when moulding a cast iron prototype of the concept. Two types of

practical tests to measure the stiffness in brake calipers are evaluated. One test where the

displaced amount of brake fluid is measured and one test where the deformation is measured

with dial indicators.

The results from the FEA show that the concept has a weight of about 3.2 kg, compared to the

weight of the original caliper at about 3.6 kg. The stiffness in the concept is about the same as

the original, even marginally better. The stress in the concept is more evenly distributed which

indicates a better use of the material.

The stiffness in the prototype does not reach the same levels as the original caliper according to

the practical tests. Possible reasons are the small scale production and insecurity of the material

properties. The methods to evaluate the stiffness in the calipers are working properly and seem to

be good methods for practical evaluation of stiffness in calipers.