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Tractors are the self-propelled vehicle which finds its major application in agriculture, haulage and construction equipment. The product development cycle time of a tractor is more as compared to automobiles since it has to undergo rigorous field testing. Bringing more realistic component and system level validation in the test lab will drastically reduce the product development cycle time. Non-availability of standard usage pattern and customer-correlated proving ground pose a bigger challenge for bringing the field conditions to the lab. As a result, the tractor has to be instrumented with sensors and load-time history needs to be acquired as per real world usage pattern. Raw data from the field cannot be used directly for lab testing since the number of load cycles will be very high. Raw data have to be edited based on damage calculation and fatigue sensitivity analysis technique.

The objective of this paper is to demonstrate that frequency domain methods for calculating structural response and fatigue damage can be more widely applicable than previously thought. This will be demonstrated by comparing results of time domain vs. frequency domain approaches for a series of fatigue/durability problems with increasing complexity. These problems involve both static and dynamic behavior. Also, both single input and multiple correlated inputs are considered. And most important of all, a variety of non-stationary loading types have been used. All of the example problems investigated are typically found in the automotive industry, with measured loads from the field or from the proving ground.

Scania AB has opened the new CD7 climatic wind tunnel test facility, located at the Scania Technical Center in Södertälje, Sweden. This facility is designed for product development testing of heavy trucks and buses in a range of controllable environments. Having this unique test environment at the main development center enables Scania to test its vehicles in a controlled repeatable environment year round, improving lead times from design to production, producing higher quality and more reliable vehicles, and significantly improves the capability for large vehicle performance research. This state-of-the-art facility provides environmental conditions from -35°C to 50°C with humidity control from 5 to 95 percent. The 13 m2 nozzle wind tunnel can produce wind speeds up to 100 km/h. The dynamometer is rated at 800 kW for the rear axle and 150 kW for the front axle, which also has ±10° yaw capability.