Transient Load Simulation of Forwarder Rear Frame
Sormunen, Juho (2016)
2016
Konetekniikan koulutusohjelma
Teknisten tieteiden tiedekunta - Faculty of Engineering Sciences
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Hyväksymispäivämäärä
2016-08-17
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201607014329
https://urn.fi/URN:NBN:fi:tty-201607014329
Tiivistelmä
One difficulty in the design of load bearing components of mobile machines is the transient and non-linear nature of loads acting on them. In addition to the dynamic characteristics of the machine, the magnitude of these loads also depends on the properties of the ground the machine is operating in. A common method for tracking these loads is to use strain gauges and force transducers on a physical test machine.
An alternative method for determining the transient loads by means of a mathematical model that intends to describe the response of John Deere 1010E forwarder as it crosses a test track is utilized in this thesis. The model is based on finite element method and it is solved using explicit time integration and LS-DYNA® software. The most challenging aspect of the simulation turned out to be the modeling of the tires, specifically the control of their high frequency vibrations.
The evaluation of the machine response using a mathematical model, at its best, is faster, cheaper and more versatile compared to physical testing. The model will be validated by comparing simulation results to measured results.
As a result of this thesis a model capable of replicating the real world with a reasonable accuracy was obtained. The forces acting on tires, which can be considered the most important results of this work, can be used as boundary conditions in consequent analyses, such as fatigue simulation. It was found out that the global stress state in the load space is dominated, at least at high loads, by the forces exerting from the cargo and not much affected by the tire forces. Tire forces do, however, affect the stress state of the welded frame itself.
In the future, this model can be used early in the design phase as a basis for a model that helps in determining the response of different machine configurations at different terrains and loading conditions.
An alternative method for determining the transient loads by means of a mathematical model that intends to describe the response of John Deere 1010E forwarder as it crosses a test track is utilized in this thesis. The model is based on finite element method and it is solved using explicit time integration and LS-DYNA® software. The most challenging aspect of the simulation turned out to be the modeling of the tires, specifically the control of their high frequency vibrations.
The evaluation of the machine response using a mathematical model, at its best, is faster, cheaper and more versatile compared to physical testing. The model will be validated by comparing simulation results to measured results.
As a result of this thesis a model capable of replicating the real world with a reasonable accuracy was obtained. The forces acting on tires, which can be considered the most important results of this work, can be used as boundary conditions in consequent analyses, such as fatigue simulation. It was found out that the global stress state in the load space is dominated, at least at high loads, by the forces exerting from the cargo and not much affected by the tire forces. Tire forces do, however, affect the stress state of the welded frame itself.
In the future, this model can be used early in the design phase as a basis for a model that helps in determining the response of different machine configurations at different terrains and loading conditions.