Search Results

Gasketed bolted joint analysis tools are gaining importance as the market place demands superior product performance, reduced cycle time, and lower cost. Design analysis tools can be used to predict product performance over the life of the joint. Numerous design concepts under a range of operating conditions can be simulated. The optimal designs can be determined before a prototype is manufactured and tested. The reduction in prototyping and testing results in cost savings and a reduction in design time. The customer is provided with a product with superior sealing performance at a lower cost. This paper presents a design analysis technique which uses a non-linear finite element program in conjunction with a spreadsheet. The spreadsheet functions as a user friendly input and output interface to the finite element program. Parametric models are used to define the geometry of standard sealing system components that include gaskets, flanges, and fasteners.

Many gaskets have constructions that combine structures of varying compressive stiffness. Low stiffness features may be used for coolant and oil seals; while, extremely stiff components could be used around a fastener as a load stop or around a combustion opening as part of a combustion seal. The use of a high stiffness stopper as part of a combustion seal has a significant effect on the overall behavior of the gasket. The stopper influences the distribution of total bolt load over the entire gasket by concentrating load toward the combustion opening. In the case of multi-layer steel gaskets, fluctuating loads on the combustion seal such as the head lifting force that is generated from the cylinder firing pressure are split between high stiffness stoppers and lower stiffness embosses that surround the combustion opening. In this paper, we will look at the basic mechanics of combustion seal stoppers and consider the effect of the stopper on combustion seal performance.

A bolted joint mathematical model is presented which includes flange bending effects. The approach simulates the behavior of a system of elastic flanges, a one component non-linear gasket, and linear elastic bolts subjected to assembly and pressurization loadings. Flange distortion is introduced to the joint diagram to predict the overall, midspan, and under the bolt gasket loads.