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Zaletelj H.,University of Ljubljana | Haesen V.,Bosal Emission Control Systems | Dedene L.,Bosal Emission Control Systems | Fajdiga G.,University of Ljubljana | Nagode M.,University of Ljubljana
Materials and Design | Year: 2013

Fatigue loading appears frequently at many machine parts and it can, under certain conditions, cause a failure. Many parts of an internal combustion engine are subjected to a raised temperature where the fatigue properties are different than they are at room temperature. The exhaust system is one of the parts that are loaded with fatigue at different temperatures, known as thermo mechanical fatigue (TMF). Welds are used frequently in the exhaust system and present critical locations for crack initiation. During loading initial crack can propagate through a section to a final failure, so if the lifetime of the exhaust system is determined by the results of a base material, it can be misjudged. In the paper it is presented that the fatigue degradation regards to the weld influence. Test sample preparation, material and special high cycle fatigue testing manner are also presented. Test specimens without weld, with weld and additionally with aging influence are used. The material exposure to increased temperature over time affects the stress-strain response and other mechanical properties. This effect is known as aging and the results of this influence on the fatigue of welded parts are presented and discussed. © 2012 Elsevier Ltd.

Seruga D.,University of Ljubljana | Hansenne E.,Bosal Emission Control Systems | Haesen V.,Bosal Emission Control Systems | Nagode M.,University of Ljubljana
International Journal of Mechanical Sciences | Year: 2014

A damage operator approach for random non-isothermal loading is demonstrated in this paper. The approach is then used to predict the damage of a thermomechanically loaded exhaust muffler. Material properties of the basic material and the weld have been treated separately. The results from thermal and structural analyses using FEA have been applied to the exhaust muffler in LMS Virtual.Lab and both fatigue and creep damages predicted. Tested exhaust mufflers were then subjected to the same loading conditions as in the calculation, and load cycles were repeated up to the point of failure or 2 million cycles. Simulated and test results are comparable. © 2014 Elsevier Ltd.

Cloudt R.,Bosal Emission Control Systems
SAE International Journal of Passenger Cars - Electronic and Electrical Systems | Year: 2014

A particulate matter On-Board Diagnostics method based on temperature sensing is demonstrated. The concept applies a detection filter downstream of the main particulate filter and a flow diversion pipe. A small fraction of the main exhaust flow is diverted through the detection filter. In case the main soot filter has some leakage, soot will collect on the detection filter where it reduces the filter's permeability. As a result the diverted flow is reduced. This effect is sensed by a temperature sensor placed downstream of the detection filter because the change of diverted mass flow results in a change of heating rate. This principle allows particulate filter diagnostics based on cost-effective and readily available sensing technology. Comprehensive diagnostics software is developed to interpret and assess the temperature signal. The developed diagnostics software detects particulate filter filtration inefficiency and performs plausibility checks. The concept is demonstrated using an instrumented test vehicle with purposely damaged particulate filter. The diagnostics prove successful in detecting a filtration inefficiency fault that leads to particulate matter emissions close to the 12 mg/km 2017 Euro 6 OBD Threshold Limit. © 2014 SAE International.

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