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Simulation-driven weight optimised design of fan hub

Loberg, Viktor LU (2015) MMK820 20141
Product Development
Abstract
In today’s competitive vehicle industry, fuel efficiency and weight plays a crucial role in performance and to maintain an attractive market position. The increasing technological development is opening new possibilities to design components with lighter materials. All components on Scania buses are favorably designed with as low weight as possible since the measured load on the back axis determines the passenger capacity. Because of the bus layout, the engine is located in the back of the bus and cannot be cooled by the slipstream in operation. The fan is powered by a hydraulic motor that sucks air through the radiator which cools the engine coolant.

The purpose of this project is to investigate the possibility for a material change to... (More)
In today’s competitive vehicle industry, fuel efficiency and weight plays a crucial role in performance and to maintain an attractive market position. The increasing technological development is opening new possibilities to design components with lighter materials. All components on Scania buses are favorably designed with as low weight as possible since the measured load on the back axis determines the passenger capacity. Because of the bus layout, the engine is located in the back of the bus and cannot be cooled by the slipstream in operation. The fan is powered by a hydraulic motor that sucks air through the radiator which cools the engine coolant.

The purpose of this project is to investigate the possibility for a material change to aluminum to reduce the weight of the fan hub which connects the fan with six bolted joints. The fan hub today is made of cast iron, a heavy structural material which creates the opportunity for a material change. Design optimisation will also be a part of the thesis, in order to remove material to save weight. Due to rear axle overhang, components in the engine compartment creates a torque load on the back axis and are substantial for maintain low weight.

The fan hub is exposed to static and dynamic loads and to be able to select a lighter material for the application, the hub needs to be simulated in order to establish the stresses generated from the different load cases. The load cases were simulated and evaluated in Abaqus and CATIA V5 GAS. The FE-results showed that preloading on the bolted joint which fixes the hub in axial direction, will be the most stressful in the keyway of the hub. Proposals came up to change the axis design in order to decrease the pressure inside the cone of the hub. The axis designs turned out to be critical in a fatigue perspective, since aluminum is a softer material than steel and when in contact with each other, wear would be inevitable due to play between hub and shaft.

A design model was established with a reduced mounting torque of the bolted joint and the keyway had to be removed, in order to reduce stresses in the cone of the hub. These measures made it possible for a material change to aluminum and the most suitable alloy would be sand cast T6 42100, a standard aluminum alloy at Scania. From the topology optimisation design proposals were generated and evaluated in CATIA GAS. The results showed that material in the periphery is unnecessary and the hub should be designed with three spokes. An optimised hub in aluminum resulted in 84% weight loss and if cast iron is kept as material, the weight is reduced to 62%. (Less)
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author
Loberg, Viktor LU
supervisor
organization
alternative title
Simulation-driven design of fan hub
course
MMK820 20141
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Cooling system, Fan hub, Simulation-driven design, Topology Optimisation
report number
ISRN14/5511 SE
language
English
id
5276752
date added to LUP
2015-04-21 14:06:49
date last changed
2015-04-21 14:06:49
@misc{5276752,
  abstract     = {In today’s competitive vehicle industry, fuel efficiency and weight plays a crucial role in performance and to maintain an attractive market position. The increasing technological development is opening new possibilities to design components with lighter materials. All components on Scania buses are favorably designed with as low weight as possible since the measured load on the back axis determines the passenger capacity. Because of the bus layout, the engine is located in the back of the bus and cannot be cooled by the slipstream in operation. The fan is powered by a hydraulic motor that sucks air through the radiator which cools the engine coolant.

The purpose of this project is to investigate the possibility for a material change to aluminum to reduce the weight of the fan hub which connects the fan with six bolted joints. The fan hub today is made of cast iron, a heavy structural material which creates the opportunity for a material change. Design optimisation will also be a part of the thesis, in order to remove material to save weight. Due to rear axle overhang, components in the engine compartment creates a torque load on the back axis and are substantial for maintain low weight.

The fan hub is exposed to static and dynamic loads and to be able to select a lighter material for the application, the hub needs to be simulated in order to establish the stresses generated from the different load cases. The load cases were simulated and evaluated in Abaqus and CATIA V5 GAS. The FE-results showed that preloading on the bolted joint which fixes the hub in axial direction, will be the most stressful in the keyway of the hub. Proposals came up to change the axis design in order to decrease the pressure inside the cone of the hub. The axis designs turned out to be critical in a fatigue perspective, since aluminum is a softer material than steel and when in contact with each other, wear would be inevitable due to play between hub and shaft.

A design model was established with a reduced mounting torque of the bolted joint and the keyway had to be removed, in order to reduce stresses in the cone of the hub. These measures made it possible for a material change to aluminum and the most suitable alloy would be sand cast T6 42100, a standard aluminum alloy at Scania. From the topology optimisation design proposals were generated and evaluated in CATIA GAS. The results showed that material in the periphery is unnecessary and the hub should be designed with three spokes. An optimised hub in aluminum resulted in 84% weight loss and if cast iron is kept as material, the weight is reduced to 62%.},
  author       = {Loberg, Viktor},
  keyword      = {Cooling system,Fan hub,Simulation-driven design,Topology Optimisation},
  language     = {eng},
  note         = {Student Paper},
  title        = {Simulation-driven weight optimised design of fan hub},
  year         = {2015},
}