Neste trabalho foi desenvolvido o material e o processo de fabricação, que possibilitasse a fabricação de grampo de feixes de mola para veículos comerciais leves, médios e pesados, sem a necessidade de aplicação de tratamentos térmicos como têmpera e revenido. Assim, foram desenvolvidos/analisados cinco tipos de aço com adição de cromo, níquel e silício que possibilitassem a conformação a frio do grampo, garantindo as propriedades mecânicas requeridas pelos grampos, tais como: resistência à tração (900 MPa mín.), limite de escoamento (720 MPa mín.), alongamento(10% min.) e dureza(24-32 HRC). Os aços desenvolvidos exibiram uma microestrutura composta de grãos de perlita e ferrita, sendo que o tamanho de grão perlítico (ASTM) entre 9 a 11 foi obtido pela adição dos elementos de liga alumínio e vanádio que atuaram como refinadores de grão. A avaliação das propriedades mecânicas foram realizadas segundo a norma ASTM A-370 e os corpos de prova foram ensaiados em um sistema dinâmico MTS 810. As análises microestruturais dos aços, após a deformação a frio, foram realizadas por meio de microscopia ótica e eletrônica de varredura, com o objetivo de se identificar a deformação a frio nas áreas desejadas. A validação final do aço e do processo de fabricação do produto foi obtida após a conclusão do ensaio de fadiga que foi realizado em temperatura ambiente, sob carregamento cíclico tração-tração com R = 0,1 e freqüência de 30 Hz, onde a metodologia Probabilidade acumulada da falha (Weibull) foi utilizada para auxiliar na conclusão final do projeto. Foi observado que o aço tipo-4 com adição de cromo (0,21%) apresentou o melhor resultado em fadiga. / In this present work the steel and the production process was developed, in order to produce U-Bolts to light, medium and heavy commercial vehicles, without any heat treatment, such as heating and tempering. Thus, this search of five types of steel with chrome, nickel and silicium addictions for the U-Bolts cold forming, assuring the mechanical properties required, as, strength (900 MPa min), yield stress (720 MPa min), elongation (10% min) and hardness (24-32 HRC). The developed steel exhibited a microstructure composed by perlite and ferrite, with the perlite grain size (ASTM) from 9 to 11, as aluminum and vanadium acted as grain size refiners. The evaluation of the mechanical properties was made according to ASTM A-370 and the samples tested in a dynamic system MTS 810. The microstructure analyses of the steel after cold forming were made using optical and scanning eletronic microscopic, in order to identify the cold forming process. For the steel and the production process validation a techniques fatigue test. They were carried out under a load-controlled (tensile-tensile), R = 0,1 and 30 Hz frequency, using the Weibull statistic method, to the final conclusion of he project. Type-4 steel with chrome addiction (0,21%) presented the best result in the fatigue test.

Simulations are a powerful tool used to reduce development time and cost in the vehicle industry. However, the models used in simulations are simplifications of reality, and there are commonly contradicting requirements between accuracy and computational efficiency. Vehicles are constructed with a large number of parts joined together with bolts, welds and other joints. At these locations and other places where different surfaces come in contact, the contact can have a considerable effect on the dynamic behaviour of the part and capturing this effect in simulations can be difficult because of their nonlinear nature.  This thesis aims to evaluate different methods for simulating contacts and their effects under dynamic conditions. The thesis is performed at Scania, one of the top commercial vehicle manufacturer, which aims to increase the use of simulations in the design of their vehicles to have better designs with lower cost and time investments.  This thesis uses the multibody simulation software Adams Car to evaluate two different contact simulation methods, one developed by Adams and the other is the softwareMamba developed by Magna. Mamba defines special modes called Joint-interface modes, which capture the deformation in the vicinity of the contact. The contact simulations are compared with some of the existing simulation methods and physical test data by implementing it on cases where contact plays an important role in dynamic behaviour. Two such cases are identified as the leaf spring and the frame-subframe assembly. For the leaf spring example, the stiffness and energy dissipation were compared for Mamba simulations with the Adams built-in multi-beam model and physical test data. The stiffness with the Mamba contact model better matched the test data, but the energy dissipation was better modelled with the Adams leaf spring model. For the frame-subframe assembly, the effect of the Mamba contact modes was evaluated for random vibration tests by comparing acceleration Power Spectral Density (PSD), relative displacement and Operating Deflection Shape (ODS) analysis. The Adams contact model was also implemented for this case but could not converge to a solution. Improvement in accuracy was observed with Mamba contact simulations compared to simulations which ignored contact, but with the drawback of significantly higher simulation times. / Simuleringar är ett kraftfullt verktyg som används för att minska utvecklingstiden och kostnaderna i fordonsindustrin. De modeller som används i simuleringar är dock förenklingar av verkligheten, och det finns vanligtvis motstridiga krav mellan noggrannhet och beräkningseffektivitet. Fordon är konstruerade med ett stort antal delar sammanfogade med bultar, svetsar och andra skarvar. På dessa platser och andra platser där olika ytor kommer i kontakt kan kontakten ha en avsevärd effekt på delens dynamiska beteende och att fånga denna effekt i simuleringar kan vara svårt på grund av deras olinjära karaktär. Detta examensarbete syftar till att utvärdera olika metoder för att simulera kontakter och deras effekter under dynamiska förhållanden. Examensarbetet har utförts hos Scania, en av de främsta tillverkarna av kommersiella fordon, som har som mål att öka användningen av simuleringar i utformningen av sina fordon för att få bättre konstruktioner med lägre kostnads och tidsinvesteringar. Detta examensarbete använder multikroppssimuleringsprogramvaran Adams Car för att utvärdera två olika kontaktsimuleringsmetoder, en utvecklad av Adams och denna andra är Mamba som är utvecklad av Magna. Mamba definierar ‘Joint interface modes’, som fångar upp deformationen i närheten av kontakten. Kontaktsimuleringen med Mamba jämförs med några av de befintliga simuleringsmetoderna samt fysiska testdata genom att implementera den i fall där kontakt spelar en viktig roll i det dynamiska beteendet. Två sådana fall identifieras som bladfjädern och ram-subramenheten. För blad-fjäder exemplet jämfördes styvhet och energiförlust för Mamba simuleringar med Adams inbyggda multi-balksmodell och fysiska testdata. Styvheten med Mamba-kontaktmodellen stämde bättre överens med testdata, men energiförlusten modellerades bättre med Adams bladfjädermodell. För ram-subramenheten utvärderades effekten av kontaktmoderna i Mamba för slumpmässiga vibrationstest genom att jämföra spektraltätheten för accelerationerna Power Spectral Density (PSD), relativ förskjutning och Operating Deflection Shape (ODS) analys. Adams kontaktmodell implementerades också för detta fall men kunde inte konvergera till en lösning. Förbättring i noggrannhet observerades med Mamba kontaktsimuleringar jämfört med simuleringar som ignorerade kontakt, men med nackdelen med betydligt längre simuleringstider.