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Optimization of Front Suspension Uprights on a Three-wheeled Electric Vehicle - Ecoist

Ellerstrand, Oskar LU and Kilicasan, Erbay LU (2017) FME820 20171
Mechanics
Abstract
The master thesis was carried out as a part of the project Ecoist at Sirgomez Engineering AB, with the goal of reducing the complexity and mass of the current front suspension upright by designing a new upright from one piece, whilst also considering other aspects such as reliability and manufacturability. In order to achieve this, topology optimization was used. The inputs for the optimization needed from external programs were mainly two things; the loads acting on the upright and a generalized geometry allowing material to be removed.

In order to generate the loads acting on the upright, a multibody model of the Ecoist vehicle was built in Adams/Car, consisting of several different subsystems. The full vehicle assembly was then used... (More)
The master thesis was carried out as a part of the project Ecoist at Sirgomez Engineering AB, with the goal of reducing the complexity and mass of the current front suspension upright by designing a new upright from one piece, whilst also considering other aspects such as reliability and manufacturability. In order to achieve this, topology optimization was used. The inputs for the optimization needed from external programs were mainly two things; the loads acting on the upright and a generalized geometry allowing material to be removed.

In order to generate the loads acting on the upright, a multibody model of the Ecoist vehicle was built in Adams/Car, consisting of several different subsystems. The full vehicle assembly was then used for a number of different dynamic drive cases, from which the reaction forces and moments acting on the upright were exported. From all those different load steps, one was chosen as representative for the worst case, which was then used in the optimization.

The generalized geometry was created in Solidworks, using the old upright assembly as reference. The idea was to make it take up as much space as possible without interfering with the surrounding components. The important parts of the geometry, such as the contact surfaces and holes were kept the same, in order to be able to connect the adjacent parts without changing them.

The topology optimization was then performed in Ansys Mechanical with key areas, such as the contact surfaces and holes, excluded from the optimization since they need to retain the same size and shape. The objective function was to minimize the mass whilst the only constraint was a predefined stress limit not to be exceeded of 125 MPa, half of the yield stress for an arbitrary linear elastic material (steel in this case). Afterwards, the optimized geometry had to be smoothed in SpaceClaim in order to obtain a useful geometry, since the optimization output featured undesirably rough surfaces and sharp edges.

The final result is an upright geometry consisting of one piece rather than four pieces assembled by a number of screws. The new upright, proposedly made from aluminum alloy AlSi10Mg, has a mass of 0.9345 kg compared to the original upright assembly, which had a mass of 1.478 kg. This represents a decrease of mass with 36.8%. (Less)
Popular Abstract (Swedish)
Examensarbetet utfördes som en del av projektet Ecoist hos Sirgomez Engineering AB, med målet att reducera komplexiteten och massan av den nuvarande uprighten i främre hjulupphängningen, genom att ta fram en ny bestående av en komponent, samtidigt som hänsyn även tas till aspekter som tillförlitlighet och tillverkningsbarhet. För att uppnå detta användes topologioptimering. Indata till optimeringen som behövde tas fram från externa program var huvudsakligen två saker; lasterna som verkar på uprighten samt en generaliserad geometri som tillåter material att tas bort.

För att generera lasterna som verkar på uprighten byggdes en flerkroppsmodell av Ecoist i Adams/Car, vilken bestod av flera olika subsystem. Det sammansatta fordonet... (More)
Examensarbetet utfördes som en del av projektet Ecoist hos Sirgomez Engineering AB, med målet att reducera komplexiteten och massan av den nuvarande uprighten i främre hjulupphängningen, genom att ta fram en ny bestående av en komponent, samtidigt som hänsyn även tas till aspekter som tillförlitlighet och tillverkningsbarhet. För att uppnå detta användes topologioptimering. Indata till optimeringen som behövde tas fram från externa program var huvudsakligen två saker; lasterna som verkar på uprighten samt en generaliserad geometri som tillåter material att tas bort.

För att generera lasterna som verkar på uprighten byggdes en flerkroppsmodell av Ecoist i Adams/Car, vilken bestod av flera olika subsystem. Det sammansatta fordonet användes sedan för ett antal olika dynamiska körfall, från vilka reaktionskrafterna och reaktionsmomenten som verkar på uprighten exporterades. Utifrån samtliga utav dessa olika laststeg valdes ett ut som representant för det värsta lastfallet, och användes sedermera i optimeringen.

Den generaliserade geometrin skapades i Solidworks med den gamla uprighten som referens. Idén var att låta den ta upp så mycket utrymme som möjligt utan att komma i vägen för de angränsande komponenterna. De viktiga delarna utav geometrin, såsom kontaktytor och hål, behölls som tidigare för att koppla samman de angränsande komponenterna utan att förändra dem.

Topologioptimeringen utfördes sedan i Ansys Mechanical med nyckelområden såsom kontaktytor och hål exkluderade ifrån optimeringen eftersom dessa skulle bevara samma storlek och form. Målfunktionen var att minimera massan medan det enda bivillkoret var en fördefinierad spänningsgräns som inte fick överskridas på 125 MPa, halva sträckgränsen för ett godtyckligt linjärt elastiskt material (stål i detta fall). I efterhand var den optimerade geometrin tvungen att jämnas ut i SpaceClaim för att erhålla en användbar geometri, eftersom geometrin från optimeringen innefattade oönskade grova ytor och skarpa kanter.

Det slutliga resultatet är en geometri av uprighten som består av en enda komponent istället för fyra komponenter som är sammansatta av skruvar. Den nya uprighten, förslagsvis tillverkad av aluminiumlegeringen AlSi10Mg, har en massa på 0.9345 kg jämfört med 1.478 kg för den tidigare uprighten. Detta representerar en minskning av massan med 36.8%. (Less)
Please use this url to cite or link to this publication:
author
Ellerstrand, Oskar LU and Kilicasan, Erbay LU
supervisor
organization
alternative title
Optimering av upright på trehjuligt elfordon - Ecoist
course
FME820 20171
year
type
H2 - Master's Degree (Two Years)
subject
keywords
Suspension, Upright, Multibody dynamics, Topology Optimization
language
English
id
8917847
date added to LUP
2017-06-21 10:37:41
date last changed
2017-06-21 10:37:41
@misc{8917847,
  abstract     = {The master thesis was carried out as a part of the project Ecoist at Sirgomez Engineering AB, with the goal of reducing the complexity and mass of the current front suspension upright by designing a new upright from one piece, whilst also considering other aspects such as reliability and manufacturability. In order to achieve this, topology optimization was used. The inputs for the optimization needed from external programs were mainly two things; the loads acting on the upright and a generalized geometry allowing material to be removed.

In order to generate the loads acting on the upright, a multibody model of the Ecoist vehicle was built in Adams/Car, consisting of several different subsystems. The full vehicle assembly was then used for a number of different dynamic drive cases, from which the reaction forces and moments acting on the upright were exported. From all those different load steps, one was chosen as representative for the worst case, which was then used in the optimization.

The generalized geometry was created in Solidworks, using the old upright assembly as reference. The idea was to make it take up as much space as possible without interfering with the surrounding components. The important parts of the geometry, such as the contact surfaces and holes were kept the same, in order to be able to connect the adjacent parts without changing them.

The topology optimization was then performed in Ansys Mechanical with key areas, such as the contact surfaces and holes, excluded from the optimization since they need to retain the same size and shape. The objective function was to minimize the mass whilst the only constraint was a predefined stress limit not to be exceeded of 125 MPa, half of the yield stress for an arbitrary linear elastic material (steel in this case). Afterwards, the optimized geometry had to be smoothed in SpaceClaim in order to obtain a useful geometry, since the optimization output featured undesirably rough surfaces and sharp edges.

The final result is an upright geometry consisting of one piece rather than four pieces assembled by a number of screws. The new upright, proposedly made from aluminum alloy AlSi10Mg, has a mass of 0.9345 kg compared to the original upright assembly, which had a mass of 1.478 kg. This represents a decrease of mass with 36.8%.},
  author       = {Ellerstrand, Oskar and Kilicasan, Erbay},
  keyword      = {Suspension,Upright,Multibody dynamics,Topology Optimization},
  language     = {eng},
  note         = {Student Paper},
  title        = {Optimization of Front Suspension Uprights on a Three-wheeled Electric Vehicle - Ecoist},
  year         = {2017},
}