https://repositorium.sdum.uminho.pt/bitstream/1822/23277/1/6.7.12%202009.pdf

Modeling and simulation of wear in revolute clearance joints in multibody systems

http://www2.mae.ufl.edu/nkim/Papers/paper34.pdf

Numerical integration schemes and parallel computation for wear prediction using finite element method

Simulation of wear and contact pressure distribution at the pad-to-rotor interface in a disc brake using general purpose finite element analysis software

Passenger car disc brakes are safety-critical components whose performance depends strongly on contact conditions at the pad-to-rotor interface. The interface can be classified as a conformal dry s ...

Experimental and numerical analysis of dry contact in the pin on disc test

In order to predict wear and eventually the life-span of complex mechanical systems, several hundred thousand operating cycles have to be simulated. Therefore, a finite element (FE) post-processor is the optimum choice, considering the computational expense. A wear simulation approach based on Archard's wear law is implemented in an FE post-processor that works in association with a commercial FE package, ABAQUS, for solving the general deformable–deformable contact problem. Local wear is computed and then integrated over the sliding distance using the Euler integration scheme. The wear simulation tool works in a loop and performs a series of static FE-simulations with updated surface geometries to get a realistic contact pressure distribution on the contacting surfaces. It will be demonstrated that this efficient approach can simulate wear on both two-dimensional and three-dimensional surface topologies. The wear on both the interacting surfaces is computed using the contact pressure distribution from a two-dimensional or three-dimensional simulation, depending on the case. After every wear step the geometry is re-meshed to correct the deformed mesh due to wear, thus ensuring a fairly uniform mesh for further processing. The importance and suitability of such a wear simulation tool will be enunciated in this paper.

http://iopscience.iop.org/article/10.1088/0965-0393/13/1/005/pdf

Finite element based simulation of dry sliding wear

A very efficient, incremental implementation of Archard’s wear model on the global scale for pin wear and disc wear in a pin-ondisc tribometer is presented. The results from the model are in good agreement with experimental results. The identified wear model is implemented in a finite element based tool (Wear-Processor) for 3D wear simulations and the results compare favorably with that from the global wear modeling scheme.

Modeling and simulation of wear in a pin on disc tribometer

Bars cyclically loaded by oppositely concentrated forces via rollers are appropriate test specimens for the determination of fatigue under contact loading. The contact strengths and numbers of cycles to failure under contact loading were determined for coarse-grained alumina. From theoretical considerations, it can be concluded that delayed failure in contact fatigue tests is caused by a reduction of the friction between the crack surfaces due to cyclic loading and the related increase of the effective stress intensity factor until the fracture toughness is reached.



Ermudungsversagen von grobkornigem Al2O3 unter Kontaktbelastung



Die beidseitige Zylinderbelastung stellt einen geeigneten Versuch zur Ermittlung des Ermudungsverhaltens unter Kontaktbelastung dar. Messungen an einem grobkornigen Al2O3 werden dargestellt. Theoretische Betrachtungen fuhren auf die Interpretation des Ermudungseffekts als Folge einer Veranderung der Rissflankenreibung mit der Zahl der Belastungszyklen.

Fatigue failure of coarse‐grained alumina under contact loading

Usual strength and fatigue experiments for ceramic materials determine the failure behaviour at simple stress states with small stress gradients. Recently, ceramics have been also used in applications like gears and pumps because of their outstanding tribological properties compared to metals. The resulting contact loading causes a multi-axial inhomogeneous stress state with high stress gradients, which have to be considered in the experimental characterisation and failure prediction. A new method for prediction of the contact strength and contact fatigue behaviour of ceramic components under normal, sliding, and cyclic contact loading has been developed [1]. The method is implemented in a fast Contact Design-Tool (CDT), that works independent from FEM methods and can be used to assess the lifetime and the failure probability of the loaded ceramic. Results obtained from the Contact Design-Tool for the friction contact of a continuous variable transmission gear [2] show an exponential dependency of the maximum allowed normal pressure in dependency of the friction coefficient of the system. The results indicate, that contact fatigue under spherical loading of alumina is expected only for radii lower than 15 mm.



Versagensbewertung von Aluminiumoxid im ungeschmierten einsinnigen Gleitkontakt



Gewohnliche Festigkeits- und Ermudungsmessungen an keramischen Materialien dienen der Ermittlung des Versagensverhaltens unter einfachen Spannungszustanden mit geringen Spannungsgradienten. In neueren Entwicklungen werden Keramiken aber auch in Getrieben und Pumpen eingesetzt, da sie im Vergleich zu Metallen ausergewohnliche tribologische Eigenschaften aufweisen. Die resultierenden Kontaktbelastungen bewirken einen mehrachsigen inhomogenen Spannungszustand mit hohen Spannungsgradienten, die bei der experimentellen Charakterisierung und Versagensvorhersage zu berucksichtigen sind. Experimentelle Methoden zur Messung der Kontaktfestigkeit und Kontaktermudung von Keramiken unter Normal-, Gleit-, und zyklischer Belastung und entsprechende Modelle wurden in [1] entwickelt. Diese Modelle wurden in ein schnelles Contact Design-Tool (CDT) implementiert, das unabhangig von Finite-Elemente-Methoden arbeitet und die Lebensdauer und Ausfallwahrscheinlichkeit der belasteten Keramik berechnet. Ergebnisse, die mit Hilfe des Contact Design-Tools fur den Reibkontakt eines CVT-Getriebes (continuous variable transmission, s. Ref. [2]) ermittelt wurden, zeigen ein exponentiell abfallendes Verhalten des maximal zulassigen Normaldrucks mit zunehmender System-Reibzahl. Daruber hinaus konnte gezeigt werden, dass Kontaktermudung fur Aluminiumoxid unter Kugelkontakt nur unter einem effektiven Radius von 15 mm zu erwarten ist.

Failure assessment of alumina in unlubricated unidirectional sliding contact

Common strength and fatigue experiments for ceramic materials determine the failure behaviour at simple stress states with small stress gradients. Recently, ceramics are also used in applications like gears and pumps because of, compared to metals, their outstanding tribological properties. The resulting contact loading causes a multi axial inhomogeneous stress state with high stress gradients, which has to be taken into account in the experimental characterisation and failure prediction. A new method for prediction of the contact strength and contact fatigue behaviour of ceramic components under normal, sliding, and cyclic contact loading has been developed. The method is implemented in a fast Contact Design-Tool (CDT), that works independent from FEM methods and can be used to assess the lifetime and the failure probability of the loaded ceramic. Results obtained from the CDT for the friction contact of a continuous variable transmission gear show an exponentially decreasing dependence between the maximum allowed normal pressure and the friction coefficient of the system.

O. Kraft

Papers

Finite element based simulation of dry sliding wear

Modeling and simulation of wear in a pin on disc tribometer

Fatigue failure of coarse‐grained alumina under contact loading

Failure assessment of alumina in unlubricated unidirectional sliding contact

5700 - a fast design-tool for ceramics under static and cyclic contact loading