Subjectively, road-based vehicular operation is one of the tough assessments of how a vehicle endures the forces it encounters during its operational life cycle. A vast combination of dynamic forces act upon the vehicle that puts the product life and durability to its proof.
Road load data acquisition and analysis, RLD(A) is an excellent method for measuring precise vehicle response to such varying loads. It considers many types of essential vehicle and driving parameters such as mass, inertia, air and rolling resistance, road characteristics, engine loads, vehicle speed and much more.
There are multiple validation tests for a given vehicle, from crash testing to vehicle stability, from break force distribution to proving the vehicle for elements and so on. While each variant of vehicle is a product of all these checks and validations, the overall endurance and product life estimate only happens when the FBU (fully built unit) is put to actual road testing over its real-life exposure scenario.
The final intent of such an elaborate testing protocol and its validation is to summarise the vehicle performance and durability to a set of manageable data that can be further consolidated for accelerated testing.
Sample data sets obtained from RLD acquisition
In a nutshell, the durability testing process follows the following steps
- Determine the physical quantities required for RLD, these may include vibration, forces, strains, temperature, wind incidence, engine loads, road-wheel interactions etc.
- Configure the vehicle with all the required sensors and instrumentation, use appropriate multi-mode data acquisition hardware platforms to acquire a variety of data. This is the crucial stage of the activity as much of the care of fixing the sensors, their calibration, wiring and connections, instrument specific settings are to be done to acquire the most possible correct data all through the testing schedule.
- The drive duration and road / route profile selection are another important consideration to make as this sets the operational limits and endurance estimates based on the known exposure of the considered vehicle during its projected service life.
Typical parameters assessed in a RLD(A) test
Load Data Compilation
For many reasons, the plan of gathering comprehensive Road Load Data is to do a first hand validation of the vehicle's durability. That said, the gathered data from a real life testing needs to be reduced to manageable numbers for benchmarking the load criteria determination. In specific cases, some of the data thus generated will also be used for accelerated testing such as PSD based vibration testing, 4 post road load simulation etc.
Accelerated testing approaches using RLD data
Derivatives and End goals
The output data of a RLD and its interpretation greatly helps in assessing the product durability and fatigue life for the considered type of vehicle, its sub-systems and the type of loading and road conditions. In addition, the scope extends to understanding the failure modes and conduct effect analysis (FMEA) that bring up a closed loop design and optimisation cycle. The matrix of considered type of variables both in terms of physical quantities and road load conditions decides the accuracy and effectiveness of the improvement cycle and designing improved vehicles that endure fully to their operational cycle.
NV Dynamics actively works on conducting RLD with multiple combinations of inputs data as applicable and relevant to the case. Our experience in conducting such tests ranges from new generation electric 2/3 wheelers to missile carrier trucks to cargo vehicles and more.