They can be quite effective for comparing the load-carrying capability, scuff resistance and several other variables between two bearings. However, simulating the actual operating conditions inside an internal combustion engine is far more difficult.

—Kevin Hoag, staff engineer in SwRI’s Engine, Emissions and Vehicle Research Division

Those evaluations currently require an engine test cell, which means high costs, limited instrumentation capabilities and a complex operating environment in which oil degradation can occur from many sources, making it difficult to isolate a particular variable for study.

SwRI engineers, using internal research funding, have already completed preliminary design work and concept evaluation on a dynamic bearing test rig that allows the operator to specify and control the load and engine speed-versus-time (crank angle) to which the bearings are subjected.

The dynamic bearing test rig will:

• Duplicate the dynamic loading seen in the engine, especially the rate of main and rod bearing load increase during combustion;

• Duplicate the shaft speed versus time seen during engine start-up; and

• Include through-the-shaft lubrication, further replicating the environment seen by the connecting rod bearings.

Under the aegis of the new consortium, researchers will construct a test rig based on that initial design, demonstrate its operation and ability to meet measured parameters that mirror engine operating conditions, and further develop it into a useful tool for designing and testing engine bearings as well as lubricants.

The test rig developed under this endeavor will be supported by a full-service tribological laboratory and an experienced engine development organization. Testing conducted with this rig will be complemented with standard tribological interface testing and analysis, motored friction engine testing, in-situ engine wear measurement using radioactive tracer technology, and detailed engine lubrication and bearing system modeling. SwRI is also active in diamond-like coatings (DLC) and nanocomposite coating and process development targeted at internal combustion engine applications.

Intended test types include:

• Engine start-up and shutdown wear quantification
• Scuff onset under various conditions
• Bearing fatigue life under various conditions
• Depending on client interest, rig will be sized for automotive or heavy-duty applications. It is anticipated that two rigs will be constructed to best optimize for each.

Intended bearing types include:

• Connecting rod “big end” bearings
• Further plain hydrodynamic bearings – mains, cam bearings, others
• Dependent on client interest: Roller bearings and non-hydrodynamic bushings

Membership in the consortium means that manufacturers and suppliers of engines, bearings and lubricants can share pre-competitive research results without having to shoulder the full price for developing a new-generation bearing test rig.

A kickoff meeting for the consortium is scheduled 24 Sept. at SwRI’s headquarters in San Antonio. Membership is $49,900 per year for the multi-year consortium.