Disc brakes, which are essential safety components in automobiles, are profoundly affected by conditions at the pad-to-rotor interface. In this research, 3D modeling of the brake system was conducted using CATIA, supplying a comprehensive visual representation crucial for our analysis. The finite element analysis (FEA) was performed with ANSYS Workbench, allowing for an in-depth examination of wear mechanisms and their associated temperature history. To closely mirror real-world scenarios, tests were conducted using the Bruker UMT system equipped with a heating chamber, adhering to the SAE J2522 standard. Despite the robust methodologies employed, achieving the desired wear performance proved challenging. A significant inconsistency was observed between experimental and the simulation results. This disparity underscores potential inadequacies in the current simulation models and highlights the need for a more precise inclusion of material properties. This study recommends refining these models, addressing their inherent limitations, and optimizing testing parameters. A pivotal suggestion is incorporating enhanced material properties into the 3D models to improve accuracy. With these enhancements, the aim is to bridge the gap between simulated and real-world brake wear performances, thereby promoting more reliable braking systems.

Friction brakes represent the most important safety feature literally in all vehicles and their rigorous “friction testing” is usually performed on several platforms/scales and completed with field tests. Since friction and wear are system properties, it is not trivial to design “small scale” tests and to correlate data generated at different levels of testing complexity. Nevertheless, the economy of the brake materials development process could be improved, when interpretation of friction and wear test data is based on a deeper/proper understanding of physics and chemistry of ongoing friction phenomena. This contribution follows the two series previously presented at SAE Brake Colloquia and compares the data generated in the full-scale brake dynamometer SAE J 2522 performance test (Link Engineering 2800M dynamometer) with data generated in bench-top (small scale) friction tester (Bruker UMT) equipped with environmental chamber controlling temperature. Scaling laws of physics were adopted for design of the small-scale testing procedure, however, a different scaling philosophy as well as different friction materials were used when compared to the previously reported findings. Identical commercial OEM brake pad samples containing biodegradable environmentally friendly fibers and commercial OEM cast iron rotors were used in both dynamometer and scaled-down bench-top friction tests. Friction and wear surfaces/mechanisms were studied by using scanning electron microscopy (Quanta FEG 450 by FEI) equipped with the energy dispersive X-ray microanalysis (Inca System), and 3D optical microscope (NPFLEX by Bruker). Major conclusions proposed for this study can be summarized as follows: 1) Proper scaling by using physics principles allows for reasonable correlation of dynamometer and bench-top test data, although the results differentiate, particularly during fade and high temperature tests. These findings further support the previously published data and indicate that differences in scaling philosophy neither the types of tested materials have considerable impact on the generated data. 2) It is very important to properly select representative pad samples, as their size is considerably smaller compared to full pads. When the identical rotor materials are used, the repeatability of data is excellent and the sensitivity to typical differences of the bulk microstructure of cast iron is minimal. 3) When the testing results generated on dynamometer and bench tester matched well. the friction surfaces of full pads tested in dynamometer and the friction surfaces of small pad samples exhibited identical topography and chemistry.

Syftet med detta examensarbete var att bestämma enhetstider som används för prissättning och produktionsplanering av ytterväggar vid LB-Hus AB. Syftet var också att utforma en standard för kommande tidmätningar vid förtaget. Som hjälpmedel vid tidmätningarna har programvaran Umt-Plus använts. För att underlätta vid kommande mätningar vid företaget har enklare instruktioner för de vanligaste funktionerna i programmet tagits fram och arbetsgången noggrant dokumenterats. Under genomförandet av tidmätningarna har produktionsprocessen granskats och de problem som har uppmärksammats är bl a. oklarheter i ritningsunderlagen som snabbt orsakar störningar i produktionen och att de beredningsmissar som förekommer ofta resulterar i onödigt dubbelarbete. De uppmätta enhetstiderna stämmer väl överens med de tider som i dagsläget används av företaget. Dock har bara en linje undersökts och vidare undersökningar bör göras vid de andra linjerna för att med säkerhet kunna bekräfta de tider som används. Vid studien har verkningsgraden vid linjen uppmätts till 74 % och det är lägre än vad LB-Hus AB använder sig av vid sin kalkylering. Skillnaden mellan verklig verkningsgrad och den antagna kan vara en orsak till att det i nuläget behövs en hel del övertid för att hinna med den produktion som läggs ut i fabriken.

<p>Syftet med detta examensarbete var att bestämma enhetstider som används för prissättning och produktionsplanering av ytterväggar vid LB-Hus AB. Syftet var också att utforma en standard för kommande tidmätningar vid förtaget.</p><p>Som hjälpmedel vid tidmätningarna har programvaran Umt-Plus använts. För att underlätta vid kommande mätningar vid företaget har enklare instruktioner för de vanligaste funktionerna i programmet tagits fram och arbetsgången noggrant dokumenterats.</p><p>Under genomförandet av tidmätningarna har produktionsprocessen granskats och de problem som har uppmärksammats är bl a. oklarheter i ritningsunderlagen som snabbt orsakar störningar i produktionen och att de beredningsmissar som förekommer ofta resulterar i onödigt dubbelarbete.</p><p>De uppmätta enhetstiderna stämmer väl överens med de tider som i dagsläget används av företaget. Dock har bara en linje undersökts och vidare undersökningar bör göras vid de andra linjerna för att med säkerhet kunna bekräfta de tider som används. Vid studien har verkningsgraden vid linjen uppmätts till 74 % och det är lägre än vad LB-Hus AB använder sig av vid sin kalkylering. Skillnaden mellan verklig verkningsgrad och den antagna kan vara en orsak till att det i nuläget behövs en hel del övertid för att hinna med den produktion som läggs ut i fabriken.</p>

As urban development in the 20th century has become the issue of global concern, more and more new territories have been occupied due to high intensity of the development. International conferences devoted to the regulatory issues of city development held within the current decade (such as HABITAT II held in Istanbul, 1996, ATHENS’98 – in Athens, 1998, URBAN 21 – in Berlin, 2000, and a conference in Brussels, 2001, etc) emphasized the majority of developmental aspects including the great focus on the necessity to further form urban structures with the priority of internal city development looking for more effective and more universal functional uses of the territories, restoration of the existing downtown areas and preservation of their original character. As other post-soviet countries, Lithuania has been also facing the need to reorganize various spheres including urban development. Urban territories have been dangerously expanded, especially during the soviet period, due to the increased general city building-up areas, mostly expressed by the territorial expansion rather than gradual and consistent development (by the use of internal reserves of the city). After the restoration of Lithuanian independence, privatisation, changed character of housing construction, return of land and real estate to the previous owners and increasing value of land under the free market conditions remarkably modified the nature of urban development in Lithuania, at the same time revealing the... [to full text]

As urban development in the 20th century has become the issue of global concern, more and more new territories have been occupied due to high intensity of the development. International conferences devoted to the regulatory issues of city development held within the current decade (such as HABITAT II held in Istanbul, 1996, ATHENS’98 – in Athens, 1998, URBAN 21 – in Berlin, 2000, and a conference in Brussels, 2001, etc) emphasized the majority of developmental aspects including the great focus on the necessity to further form urban structures with the priority of internal city development looking for more effective and more universal functional uses of the territories, restoration of the existing downtown areas and preservation of their original character. As other post-soviet countries, Lithuania has been also facing the need to reorganize various spheres including urban development. Urban territories have been dangerously expanded, especially during the soviet period, due to the increased general city building-up areas, mostly expressed by the territorial expansion rather than gradual and consistent development (by the use of internal reserves of the city). After the restoration of Lithuanian independence, privatisation, changed character of housing construction, return of land and real estate to the previous owners and increasing value of land under the free market conditions remarkably modified the nature of urban development in Lithuania, at the same time revealing the... [to full text]