Torsional vibrations in differentials of Rear Wheel Drive vehicles are of major importance for the automotive industry. Hypoid transmissions, forming the motion transfer mechanism from the driveshaft to the wheels, suffer from severe vibration issues. The latter are attributed to improper mesh between the mating gear flanks due to misalignments, variation of contact load and shifting of the effective mesh position. For certain operating conditions, the gear pair exhibits high amplitude motions accompanied with separation of the mating surfaces. Ultimately, single or even double-sided vibro-impact phenomena evolve, which have been related to noise generation. This thesis attempts to address these issues by effectively analysing the dynamic behaviour of a hypoid gear pair under torsional motion. The case study considered is focused on a commercial light truck. The major difference of the employed mathematical model to prior formulations is the usage of an alternative expression for the dynamic transmission error so that the variation of contact radii and transmission error can be accounted for. This approach combined to a correlation of the resistive torque in terms of the angular velocity of the differential enables the achievement of steady state, stable periodic solutions. The dynamic complexity of systems with gears necessitates the identification of the various response regimes. A solution continuation method (software AUTO) is employed to determine the stable/unstable branches over the operating range of the differential. The ensuing parametric studies convey the importance of the main system parameters on the dynamic behaviour of the transmission yielding crucial design guidelines. A tribo-dynamic investigation aims at expanding the dynamic model from pure dry conditions to a more integrated elastohydrodynamic (EHL) approach. Analytical and extrapolated solutions are applied for the derivation of the film thickness magnitude based on the kinematic and loading characteristics of the dynamic model. The temperature rise is governed mainly by conduction due to the thin lubricant films. The generated friction is also computed as a function of the viscous shear and asperity interactions. The effective lubricant viscosity is greatly affected by the pressure increase due to the resonant behaviour of the contact load. The final part of this work is involved with a feasibility study concerning the application of Nonlinear Energy Sinks (NES) as vibration absorbers, exploiting their ability for broadband frequency interaction. Response regimes associated with effective energy absorption are identified and encouraging results are obtained, showing the potential of the method.

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Orientador: Anselmo Eduardo Diniz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-03T20:42:19Z (GMT). No. of bitstreams: 1 Fontana_Douglas_M.pdf: 10116872 bytes, checksum: 3a8e7469b54d02c31d22b732a5021bb1 (MD5) Previous issue date: 2003 / Resumo: A transmissão de movimentos mecânicos através de engrenagens é muito utilizado em todos os segmentos industriais.O corte de dentes de engrenagens é uma operação bastante importante dentro da usinagem. Apesar de sua importância, este é um processo pouco estudado, pois esta é uma área bastante restrita de atuação. Emfunção disso,a maior parte dos desenvolvimentos relacionados à tecnologia de corte de dentes de engrenagens ocorre no meio industrial, geralmente de forma empírica. A determinação do fim de vida das lâminas de corte Gleasonsão feitas,no chão de fabrica,pelos preparadores ou mesmo pelos operadores das máquinas.Tal decisão é baseada em critérios altamente subjetivos e portanto, faz com que o tempo de utilização da ferramenta apresente uma grande variabilidade,ou seja, em determinados momentos, a ferramenta é utilizada além de sua vida efetiva e, em outros momentos, esta utilização se dá a quém da mesma. Caso a ferramenta ultrapasse sua utilização ótima, ocorrem vários problemas, dentre os quais: maior volume de material retirado na afiacão da ferramenta com conseqüente redução do númerode vidas desta, a rugosidademédia (Ra) das peças toma-se muito elevada,fazendo com que a japidação do dentado (operação posterior ao corte) seja muito demorada e portanto, anti-econômica.Por outro lado, se a ferramenta for sub-utilizada. ocorre um desperdício de lâmina,bem como um aumento do tempo de processamento pois um maior número de trocas da ferramenta vai ocorrer. Este trabalho procurou estabelecer um parâmetro objetivo de fim de vida da lamina de corte do tipo Hardac, utilizandoo processo de corte denominado Completo (Completing). Para tanto, foi feito um trabalho junto a um fubricante de auto-peças, que usina engrenagens cônicas e hipoidais, utilizada em diferenciais de caminhões e ônibus.O parâmetro escolhido foi a rugosidade média (Ra) do flancodos dentes das engrenagens. O comportamento e a dispersão da vida da ferramenta anterior e posterior à implantação do parâmetro proposto foram analisadas.Os resultados mostram uma maior uniformidade da vida das laminas de corte gleason,bem como dos tempos de afiação das mesmas e Iapidação do dentado. Além disso, as lâminas passaram a ser utilizadas de forma otimizadas em relação ao seu desgaste e à quantidades uperficial da peça. Um segundo objetivo do trabalho foi comparar a vida de ferramentas de aço rápido com algumas coberturas diferentes e também sem cobertura na superficie de saída, pois foram utilizadas após a afiação da ferramenta com cobertura total Pelo desempenho mostrado nos resultados a melhor cobertura foi aquela de nitreto de titânio originária do fabricante da ferramenta e do equipamento / Abstract: The transmission of mechanical motion through gears is very used in alI industrial segments.The cutting process of gears is a very important process in the manufacturing. Despiteits importance this is a process not so studied as it a very specific area. According to this, most part ofthe industrial field, usually in an empirical way. The determination to end the life of a Gleason Cutter Blade is made by machine operators. The decision is based on highly subjective criteria and as for this it makes the using time of this tool to presenta great variability. As resuh this tool is sometimes used longeror less than it should.If its use is longer exceedingits life time,many problems may occur, such as: bigger volume taken from the sharpening material of tools which results in a reduction of their lifetime, the average rougbness (Ra) of the parts becomes higher which makes lapping of the teeth (process which occurs after cutting) to take longer and as a resuh not economical.On the other hand,if the tool is used less there is a waste ofthe blade as well as an increasein the manutacturing process due to the change of tools. This work tried to establishan objetive parameteron the end ofthe life ofthe Hardac type ofblade, using a cutting process called Completing.For this reason this work was done together with an Automotive Company that produces beveland hypoidgears used on heavyduty drive axles for trucks and buses. The chosen parameter was the average rougtmess(Ra) ofthe teeth flankof the gears. The behavior and dispersion of the tool Jife before and after the setting of the proposed parameter were analized. The resuhs show a greater uniformity of the life the Gleason Cutter Blade as well as its sbarpeningtime and teeth lapping. Apart from it, the blades started to be used on an optimized way related to its wear and to the surlace quality of the piece. Another objetive of this work was to compare the high speed steel tool life with some different coats andalso no coating on theftont ceplane,as theywere used after the tool sharperning with total coat. For the result showed the best coating was the one with titanium nitrideoriginate dftom the tool and equipamentmanufacturer / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

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Det amerikanska företaget Meritor är en globalt ledande leverantör av lösningar för bland annat drivlinor, bromsning och rörlighet till både industri- och kommersiella fordon. Meritor HVS AB:s fabrik, belägen i Lindesberg, är främst inriktad på montering av kompletta hjulaxlar samt bearbetning av komponenter, inklusive kugghjul till hypoidväxlar, till tunga fordon såsom buss och lastbil. Hypoidväxlar används i bakaxlar då de klarar av höga vridmoment samtidigt som de har en hög hållbarhet och är relativt tysta i drift. Ett steg i monteringsprocessen för växlarna på Meritor är att passa in pinjong och kronhjul, två typer av kugghjul, så att de har god kontakt mellan kuggarna. En god kontaktyta behövs för att inte påverka kugghjulens livslängd samt säkerställa tyst drift. Kontaktytan verifieras bland annat genom okulär fläckanalys av montören. Syftet med examensarbetet var att utföra en undersökning om hur kvalitetssäkringen av fläckanalysen kan förbättras i Meritors centrumväxelmontering. Visionsystem är en metod som ansetts lämpad och extra intressant att undersöka.  Under arbetet har nuläget kartlagts genom bland annat observationer, intervjuer och interna dokument såsom arbetsinstruktioner. Undersökning av kvalitetssäkringslösningar har utförts genom bland annat studiebesök. Fem stycken lösningsförslag har tagits fram varav en kombination av några av dem skulle ge en mer fullständig kvalitetssäkring. För att bestämma exakt vilken lösning som är mest lämpad så behövs en kravspecifikation tas fram vilket i sin tur kan kräva att flera olika tester behövs genomföras för att kartlägga behov och önskemål. / he American company Meritor is a globally leading provider of solutions for drivetrain, braking and mobility for both industrial and commercial vehicles. Meritor HVS AB's factory, located in Lindesberg, is primarily focused on the assembly of complete wheel axles and gears but also machining of components, including gears for hypoid gears, for heavy vehicles such as busses and trucks. Hypoid gears are used in rear axles as they can handle high torque while having a high durability as well as begin relatively quiet in operation. One step in the assembly process of the gears at Meritor is to fit the pinion and ring gears, two types of gears, so that they have good contact (mesh) between the gears. A good contact surface is necessary to not impact the life-span of the gears and to ensure quiet operation. The contact is verified through ocular contact spot analysis by the assembly worker, where the assessment may be a difficult task as well may differentiate between the assembly workers, which is a risk of false assessment. The aim of this project was to carry out a study regarding how quality assurance of the contact spot analysis can be done in Meritor's gear assembly. Vision systems are a method that is considered suitable and of extra interest to investigate. During the work, the current situation has been mapped through observations, interviews and internal documents such as operation instructions. Investigation of quality assurance solutions has been done through e.g. study visit. Five proposals for solutions have been developed where a combination of some of them would provide a more complete quality assurance. In order to determine exactly which solution that is most suited, a specification of requirements is needed to be determined. Several tests could be required to establish requirements and requests.

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This PhD thesis deals with elastohydrodynamic lubrication (EHL) under the conditions that occur between mated hypoid gear teeth. The aim is to describe experimentally the behaviour of lubricating film and mechanisms of its formation. The focus is mainly placed on clarifying the influence of direction and magnitude of sliding velocity in circular and elliptical contacts. Generally, it is still assumed that the direction of sliding velocity has no effect on the resulting lubricant film. In this study optical interferometry is used to determine distribution of lubricant film thickness. This work includes new and original results which clarify the studied problem. It was found that the direction of sliding velocity affects shape of the film at high speeds. This relates to the effect on heat flow through the contact. The results have an impact on the development of general EHL theory and provide knowledge applicable in film thickness prediction in the design of real tribological nodes.

Gears are an integral part of devices ranging from simple wrist watches to complex systems like automotive and wave energy converters. They play a very important role in the transfer of torque. There are several types of gears to be chosen from, depending on the application. This thesis work deals exclusively with hypoid gears. A hypoid gear is a type of bevel gear, that transmits torque between two non-parallel shafts. It is similar to a spiral bevel gear, except that the pinion axis can be oset. It is this ability to offset, that renders hypoidgears as highly sought-after gears for automotive applications. It is crucial that these hypoid gears are designed efficiently and that their life before failure is predictable, to a reasonable degree of accuracy. To enable such predictions, this thesis makes an effort to build a finite element (FE) model. With the developed FE model, a study of the effect of press-fit on the ring gear's root bending stresses, that is present in a hypoid gear set of a car's Rear-Drive Unit (RDU), was carried out. The FE model was built on three different software - Transmission 3D (T3D), Hypoid Face Milled (HFM) and MSC Marc (Marc). The effect of press-fit on root bending stresses of the ring gear was first analyzed on T3D. To determine if the press-fit was correctly induced, the model was rebuilt and analyzed on Marc. HFM was used to determine the effect of inclusion of different components on the root bending stresses. Additionally,the HFM model was also replicated on Marc and a press-fit of 100m was induced. This was done to see if modelling the press-fit on HFM gave similar results to that of T3D and if using HFM in conjunction with Marclead to a better modelling procedure. It was found that the maximum root bending stresses increased linearly with increasing press-fit dimension. It was also found that the inclusion of different parts does not cause a significant increase in root bending stresses, except for the inclusion of differential cage. The effect of press-fit could not be quantified despite knowing that it affects the root bending stresses. When the same analysis done on HFM or T3D was done on Marc, there wasa 10% increase in stresses at highly stressed zone in Marc model of T3D; there was 10-15% increase in stresse sat highly stressed zone in the HFM model of Marc. Hence, quantification remained an impediment. It was not possible to quantify the error that occurred during the migration of analysis from HFM or T3D to Marc. However, potential causes of these errors could be the error in computation of bearing forces and difference in the definition of contacts in the software. Owing to large computational time and limited working period, all the analysis on Marc was carried out for one position and for the first time step of the gear mesh. If the errors in migration of analysis from one software to another could be quantified, then this modelling can be used to estimate the contribution of press-fit to rootbending stresses on the ring-gear. Although the contact pattern comparison between the virtual models andthe physical test suggests that HFM is a more trustworthy software, it is recommended to conduct some straingauge measurements on different ring gear teeth and then compare the results with those of the virtual model. / Kugghjul är en integrerad del av utrustningar som sträcker sig fråan enkla armbandsur till komplexa system som bilar eller vågfrakftverkomvandlare. De spelar en mycket viktig roll vid överföring av vridmoment. Det finns flera typer av kugghjul som man kan välja från, beroende på applikationen. Detta projekt handlar exklusivt om hypoidväaxlar. En hypoidväxel är en typ av vinkelväxel som överför vridmoment mellan två icke parallella axlar. Det liknar ett spiralformat växel, förutom att kugghjulets axel kan förskjutas. Det är denna förmåga att kompensera, vilket gör hypoidväxlar en mycket eftertraktade redskap för fordonsapplikationer. Det är avgörande att dessa hypoid-redskap är konstrueras effektivt och att deras liv före misslyckande ar förutsägbart, i en rimlig grad av noggrannhet. För att möjliggöra sådana Förutsägelser gör denna avhandling ett försök att bygga en finita-element (FE) modell. Med den utvecklade FE-modellen utfördes en studie av effekten av presspassning pa ringvaxelns rotböjspänningar, som finns i en hypoid växelsats av en bilens Bakre enhet (RDU). FE-modellen byggdes på tre olika programvaror: Transmission 3D (T3D), Hypoid Face Milled (HFM) och MSCMarc (Marc). Effekten av presspassning på riggböjspänningarna hos ringväxeln analyserades först på T3D. För att bestämma om presspassningen var korrekt inducerad, byggdes modellen och analyserades på Marc. HFM användes för att bestämma effekten av inkludering av olika komponenter på rotböjspänningarna. Dessutom replikerades HFM-modellen också på Marc och en presspassning på 100 microns inducerades. Detta gjordes för att se om modellering av presspass på HFM gav liknande resultat som T3D och om man använde HFM i kombination med Marc leder det till ett bättre modelleringsförfarande. Det visade sig att de maximala rotböjspänningarna ökade linjärt med ökande presspassningsdimension. Det konstaterades ocksåa att införandet av olika delar inte orsakar en signifikant ökning av rotböjspänningar, utom införandet av differentialbur. Effekten av presspassning kunde inte kvantifieras trots att man vet det påverkar rotböjspänningarna. När samma analys gjord på HFM eller T3D gjordes på Marc, fanns det en 10% ökning av späanningar vid starkt stressad zon i Marc-modellen av T3D; det var 10-15% ökning av spänningar vid starkt stressad zon i HFM-modellen av Marc. Därför förblev kvantifiering ett hinder. Det var inte möjligt att kvantifiera felet som inträffade under analysanalysen från HFM eller T3D till Marc. Dock kan potentiella orsaker till dessa fel vara felet vid beräkning av bärkrafter och skillnad i definitionen av kontakter i programvaran. På grund av stor beräkningstid och begränsad arbetstid utfördes all analys på Marc för bara en position och för det forsta steget av växelns nät. Om felen i migration av analys från en programvara till en annan kunde kvantifieras, då kan denna modellering användas för att beräkna bidragen från presspassning till rotböjspänningar på ringväxeln. Även om kontaktmönstersjämforelsen mellan de virtuella modellerna och det fysiska testet föreslår att HFM är en mer pålitlig programvara, rekommenderas det att utföra en viss belastning Mätmätningar på olika ringväxeltänder och sedan jämföra sedan resultaten med dem från virtuella modellen.