| 1. |
- Mehrgou, Mehdi
(författare)
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Study The Transverse Vibration In A Pushrod Of A Diesel Engine Valvetrain Using Contact Element In Flexible Multibody Dynamics
- 2012
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Ingår i: Proceedings Of The ASME International Mechanical Engineering Congress And Exposition 2010, Vol 3, Pts A And B. - : ASME Press. - 9780791844274 ; , s. 121-126
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Konferensbidrag (refereegranskat)abstract
- Dynamic simulations of the engine valvetrain and detailed studies on the operating mechanisms have long been a centre of attention. In heavy duty diesel engines, heavier valvetrain parts lead to higher inertia force. On the other hand, the opening and closing of valves is very fast and high overlap in Valves lifts and necessity for increase the exhaust and inlet valve opening time by dwelling, individuates cam design basis of these engines, which cause to increase in inertia forces. A common practice in valvetrain dynamic analysis is to use rigid multibody dynamics model. However, some assumptions are to be considered to simplify the model, especially in attachments and joints. In this paper, an under development heavy duty medium speed diesel engine valvetrain system has been studied. The valvetrain mechanism has been modeled using ADAMS commercial software. The flexible valvetrain parts have been considered by means of Component Mode Synthesis (CMS) method. Instead of using simple joint assumption of rigid multibody dynamics model, contact has been employed to study the exact interaction between each two parts. In this method the clearances in the system could easily considered. The dynamic behavior of valvetrain has been investigated and the forces for the parts have been obtained and compared with rigid multibody dynamics model.
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| 2. |
- Michaloski, John, et al.
(författare)
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Push–Button Discrete Event Simulation for Analysis of Factory Floor Operations
- 2010
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Ingår i: ASME 2010 International Mechanical Engineering Congress and Exposition, IMECE 2010; Vancouver, BC; Canada; 12 November 2010 through 18 November 2010. - 9780791844274 ; 3:PARTS A AND B, s. 313-319
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Konferensbidrag (refereegranskat)abstract
- In manufacturing, Discrete Event Simulation (DES) can beeffectively used to model production and provide sustainability analysis of equipment and system operation by measuring throughput, capacity, and bottlenecks. DES allows analysis under different scenarios and conditions that can then be used to forecast more optimal system performance. For discrete parts production, DES is rarely used because of the difficulty in attaining timely and accurate statistical modeling of the equipment and process operation. In this paper we look at the use of the plant floor interoperability standard, MTConnect, as a means to improve the access to machine tool data. Given data access, we develop a Finite State Model in order to streamline Machine Tool and DES integration. A case study of a prototype Capacity Planning system using DES as a modeling back–end will be described to help in understanding resource allocation of shop floor machines to a batch of aerospace parts. Direct machine tool statistical parameterization into a Web–based DES leads to “Push–button” automated simulations.
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| 3. |
- Wärmefjord, Kristina, 1976, et al.
(författare)
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Including Assembly Fixture Repeatability in Rigid and Non-Rigid Variation Simulation
- 2010
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Ingår i: Proceedings of the ASME 2010 International Mechanical Engineering Congress & Exposition, Vancouver, British Columbia, Canada, November 12-18, 2010.. - 9780791844274 ; 3:PARTS A AND B, s. 355-361
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Konferensbidrag (refereegranskat)abstract
- The repeatability of the assembly fixtures influences the geometrical outcome of an assembly. To control the fixtures, capability studies are conducted. Those studies give however just information about the variability in a number of inspection points. In this paper, a method for transforming the variation in inspection data to variation in the contacts between workpiece and locators is described. By doing this, the fault localizing of the fixture is facilitated. Further, the accuracy of the variation simulations used to evaluate different concepts and designs can be improved. Usually, when data from a repeatability study are used as input to a variation simulation, the tolerances are only applied in the points that actually were inspected. The suggested methodology makes it possible to transform the tolerances containing the repeatability of the fixture to tolerances on the locating scheme, and they are thereby affecting every point in the simulation model, not only the inspected ones. The method is tested on a case study and the effect of including fixture repeatability in a variation simulation is investigated. ©2010 by ASME.
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| 4. |
- Wärmefjord, Kristina, 1976, et al.
(författare)
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Strategies for Optimization of Spot Welding Sequence with Respect to Geometrical Variation in Sheet Metal Assemblies
- 2010
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Ingår i: Proceedings of the ASME 2010 International Mechanical Engineering Congress & Exposition, Vancouver, British Columbia, Canada, November 12-18, 2010.. - 9780791844274 ; 3:PARTS A AND B, s. 569-577
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Konferensbidrag (refereegranskat)abstract
- During the assembly process of sheet metal parts, a lot of factors affect the final geometrical quality. It is important to have knowledge about the characteristics of as many as possible of those factors, not only to be able to reduce their effect, but also to be able to include those factors in variation simulations. Those tolerance simulations are crucial tools in early stages in automotive industry in order to predict the outcome in critical dimensions and it is of course important to have as good accuracy as possible in the simulations. One of the factors affecting the final geometry is the spot welding sequence. In this paper it is shown how the spot welding sequence affects the amount of geometrical variation in a sheet metal assembly. A method for including the welding sequence in tolerance simulations is described. Of course, it is desirable to find an optimal sequence, i.e. a sequence that minimizes the geometrical variation in the final assembly. Since this is a fast growing problem - the number of possible sequences for N welding points is N!, it is not practicable to test all possible sequences. In this work some different strategies for finding an optimal sequence are tested on several industrial case studies. The tested strategies are based on general guidelines, on minimizing variation in each welding step respectively calculations of the movements in unwelded points in each step. The strategies based on general guidelines was not successful, neither was the one based on minimization of the variation in each step. The strategy based on movements in the unwelded points seems however promising. It resulted in the best or one of the better sequences for all of the eight tested industrial case studies. ©2010 by ASME.
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