Computer Analysis Support for Northstar
The Structural Systems Performance Group of Current Product Engineering Staff (CPE) allocated two engineers to perform Finite Element analysis support during the initial design process. This is a copy of one of the monthly reports describing progress made.
PROJECT TITLE: Northstar Engine Design Support NUMBER SPSPOO11
PROJECT SPONSOR: BOC - Cadillac NamePlate
PROJECT LEADER: David McLain.
CPE PARTICIPANTS: Masoud SattarIpour"
DIV'L PARTICIPANTS: BOC Powertrain. Contact: Marv Thomson.
Assigned: John Fisher/ Bill Lychuk
PROJECT DESCRIPTION: Perform finite element analysis to aid in design decisions being made correctly
START DATE: 01/12/86 COMPLETION: 12/31/89 (Current Estimate); 08/30/89 (Original Plan)
OBJECTIVES/BENEFITS: To avoid extensive design changes being required as a result of first engine build dyno testing. Establish a base of computer models to be readily available to assist in understanding test results and guiding future design modifications.
PROGRESS ACHIEVED in Jan 1990:
CYLINDER BLOCK DEVELOPMENT: Attended meeting #10 at the Precision Engine Lab in Flint on 12/4. Presented some preliminary results of the ABAQUS solidification analysis that I am using to understand the effect of several product and process variables on the stresses in the aluminum around the cast-in liners. Attended a meeting at Central Foundry in Bedford, Indiana on 1/9 to review the development of the cast-in liner. It was decided at this meeting that cast-in liners will be mainstream for production. This decision was based on the results of all the development work that has been completed over the last year via PEL. The major remaining issue is to finalize the liner o.d. configuration so that CFD can select a supplier for the liners. The next meeting at the Precision Engine Lab is scheduled for 1/18. The first Northstar block die is ready and waiting to be shipped from Japan. First castings off this die should be shot in early March.
MAIN BEARING DEVELOPMENT: Attended select fit study group meetings at the Livonia engine plant on 12/8 and 12/15. Ken Jotzke presented the latest block bore process capabilities obtained off the Livonia block line. The process was stable and showed significantly better process capability than we recorded last spring. Ken attributed the improvements to everyone on the line identifying and eliminating many sources of variation. Improvements to the Livonia crank process appear to be more limited due to the design of the tooling. Significant variation has been attributed to the dressing of the grinding wheels which may be correctable by reprogramming the compensation algorithm. However, the machine is still limited because the grinding wheels cannot be adjusted. Individually. Northstar crank tooling will be similar to Saturn’s. We have obtained run-off data from their process and the capability appears to be very good. This newest data will be fed into the select fit simulation. The simulation results are to be reviewed at the next study group meeting on 1/15. A decision on select fit should be made in February or March.
CYLINDER HEAD AND HEAD GASKET: The structural modifications made to the prototype head reduced the stresses from 214 MPa to 92 MPa. The strength of the premium grade material in these heads is 137 MPa; therefore, the latest design should be satisfactory. The gasket loading is still biased toward the intake side, but the minimum sealing pressure is increased to 9273 psi from 7357 psi. Analysis indicates a more uniform pressure distribution with “flat” profile combustion seals. Goetz is making some gaskets with these profiles and they will be sent to the fastening lab in Flint for Fugi and tissue impressions. An analysis of the effect of the front engine mount loads on gasket sealing has been started with ADT in Flint. Initial results indicate that the gasket may not tolerate rock cycle loads which has led to some discussion with the development group at Cadillac to see if these loads can be applied on one of the dyno engines.
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