Testing: Evaluation evolution
Development on screen, in the lab, or on the track always provides certain advantages but only a mix of tests delivers proven products on time and to cost. Leading engineers tell us how
- Published in Focus.
Digital development can tell engineers almost everything about the vehicle - except how it feels
James Mullineux
Manager of fluid dynamics and simulation at Ricardo
We go to considerable effort carrying out detailed research to understand key phenomena and system response. This allows process and method simplification for application within the design context without compromising the usefulness of the analysis and so enables a fast turnaround of results to support design at the right time. And we develop toolsets enabling efficient analysis workflow, ensuring that minimum time is spent in setting-up and post-processing analyses.
Coupled and more-detailed analyses are widely used where they add value. There are certain areas where we consistently use coupled analysis such as conjugate CFD analysis where the thermal and fluid domains are solved together – or coupled 1D-3D CFD, where we use 3D CFD for the detailed analysis of a particular region with more simple 1D models providing boundary conditions from the rest of the system.
At system level, integration is becoming increasingly significant. For example, ensuring that the thermal strategy works with the emissions and fuel consumption requirements, and now the increasing significance of energy management with the rise of hybrid powertrains.
Predictions that involve deterioration such as wear caused by soot in oil, or EGR fouling, are still a challenge. Whilst there are some empirical- or probability-based approaches, testing remains dominant. Another area where CAE tools are at their limits is where input data are difficult to obtain, such as detailed material properties which may vary spatially depending on the production process.
Many of the key elements of both engine and vehicle systems are tested on their own as hardware-in-the-loop (HIL), being subjected to a predefined test program to assess performance in an isolated environment. It’s likely that much of this will remain, to ensure robustness of critical components prior to integration into the engine or vehicle, and also to continue the process of validating the analysis.
The challenge is ensuring that the operating conditions the component is subjected to are realistic and representative. Often it’s a significant effort to replicate failure modes seen in the field. This is why reliability engineering is also a key tool.
CAE and HIL allow reductions in components failing to meet their requirements. But the final requirement is for system performance, be that a vehicle’s emissions over a drive cycle or an engine’s capability to achieve performance.
System testing will remain but with the focus on developing the full system rather than ironing out problems with individual components.
Globalisation of product often leads to increased testing as some components may be localised to take advantage of lower local costs and emissions legislation. This forces the requirement to test multiple variants covering the different component sourcing, environment and legislation.
