Test Technologies Contributing to Electrification - 1. Test technologies that support the competitiveness of electric vehiclesFig. 2 PG of Nissan’s Rikubetsu Proving Ground (Hokkaido)2.3 Bench test technologies of systems/componentsFig. 3 Photograph of the road simulator (as an example of bench test equipment)current models and competing vehicles, measuring surrogate characteristics that indicate the quality of each performance aspect. While it is sometimes evaluated through comparative test drives on public roads, ensuring reproducibility in real-world conditions is challenging due to the uncontrollable traffic environment. Therefore, closed test courses called "Proving Grounds (PG)" are constructed to run the vehicles. When establishing an in-house PG, the Test Department's engineers are involved in considering and planning the concept of the PG, working collaboratively with specialized design and construction companies to create the PG. This is an integral part of the responsibilities of the Test Department's engineers. To efficiently and effectively evaluate and measure various performance aspects, it is necessary to design courses that encompass a wide range of combinations of flatness, elevation, and road surfaces. Often, real-world roads and surfaces are replicated. These may include famous roads with poor ride quality, roads that challenge road noise and “squeak & rattles”, and roads that allow assessment of handling performance, among others. Determining which types of roads should be replicated in the Proving Ground (PG) is also part of test expertise.For example, Nissan Motor Hokkaido Rikubetsu Proving Ground in Japan is designed to replicate German autobahns and country roads. During winter, it becomes the coldest test facility in Japan, where surfaces such as compacted snow and ice are reproduced for test purposes.By testing in PG, we can freely control and replicate is not so the driving conditions. However, straightforward when it comes to climate and weather conditions. Furthermore, it is difficult to isolate and accurately measure various phenomena occurring in a moving vehicle and analyze them in detail. Therefore, it is necessary to establish bench test technologies that replace or supplement on-road tests, tailored to the performance, functionality, and system being evaluated. On the left side of the V-process, the phenomenon it mechanisms are analyzed for each performance, and performance allocation to each component is conducted. On the right side of the V-process, evaluation and achievement confirmation are carried out for the system and performance. An is determining what and to what extent should be replicated, depending on the objective, which showcases the skill of the bench test engineers. For example, to evaluate the durability of the vehicle body and chassis, a road simulator is used to replicate inputs from road surfaces during driving and inputs from driving and braking forces. It reproduces forces acting on the four wheels in the front, rear, left, right, up, and down directions, as well as rotational moments around the X, Y, and Z axes. Rather than replicating the input waveforms exactly as they occur during actual driving, the waveforms are manipulated to accelerate the tests, allowing for durability evaluations in a shorter time frame. The fatigue damage is reproduced to be equivalent to the market model. However, the replication of temperature and lighting conditions is excluded since the evaluation mainly targets the fatigue strength of structures made of metallic materials.In addition to on-road tests using actual vehicles or bench tests using the entire vehicle body, it is possible to extract specific components or systems and subject them to loads equivalent to those experienced in actual vehicles. This enables the elucidation of phenomena mechanisms that are difficult to observe and measure in vehicle conditions. Moreover, due to the smaller scale of tests, it becomes easier to compare and evaluate a larger number of specifications and increase the sample size for assessing variations. When constructing such bench tests for system-level evaluations, it is essential to determine how to replicate the vehicle conditions.By breaking down the performance requirements from the vehicle level to the system level and further to the parts it becomes possible to align vehicle performance targets with the required specifications of parts. In the confirmation stage of target achievement, the evaluation is conducted in the following order: first, evaluating whether the level, important aspect here individual parts meet 34
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