Sunload Simulation Process

VARROC LIGHTING SYSTEMS is a leading global passenger car exterior lighting supplier. It provides complete solutions from design to manufacturing, which are supported by engineers and other experts in a worldwide network of modern R&D centers and factories.

Challenge

Modern automobile headlamps are complex optical components consisting of a large number of parts. The optics inside do not only work with the light shining out from the headlamp but also reflect sun rays coming from the outer world. In some cases, these might cause local overheating of certain areas inside the headlamp and lead to damage of used plastic materials. The presented study is a typical task of the optical department. Its purpose is to identify the sun direction leading to the highest concentration of sun rays on each part of the headlamp. The sun direction is defined by its azimuth and inclination, the sunlight intensity was set to a constant equal to the possible maximum. Thus, the results are always on the safe side regardless of the daytime or the orientation of the vehicle towards the Sun. The resulting maps of the sunload, created for each headlamp part, are an important input for further examinations using FEM computations studying the ability of a given sunload to create critical temperatures in headlamp parts.

Solution

The first step of the project was the coupling of the Uptimai tool with Varroc’s internal software for ray-tracing simulations. These two software use open-format files for communication, thus, there was no need to interfere with their codes. Within the created automatic loop, the Uptimai algorithm was preparing inputs for the ray-tracing software which supplied the algorithm with sunload results. Every other set of sunload computations was set to address sun directions leading to a significant response in the sunload of the examined headlamp part. There is no fixed grid of azimuth and inclination angles as in the standard process of sunload analysis. Contrary, the algorithm adaptively reacts to variations of results received from the ray-tracing software, actively predicting sun direction angles with the high possibility of an excessive value of the sunload. The step between sun direction angles is set automatically by the algorithm according to the actual needs of the solved problem without other interventions of the user. Thus, there is an optimal precision-to-cost ratio of the computation process. The resulting maps of the sunload can be depicted in the Uptimai function plot postprocessing tool. From the interpolation of the prepared surrogate model of the sunload, it can obtain results for any combination of azimuth and inclination angles within the examined domain. It also supports results generation based on a list of prescribed input combinations, so the user is able to prepare the usual analysis outputs presented on an even grid with the specified resolution.

Fig. 1. Resulting sunload maps generated for selected headlamp parts

Benefits

• Quick identification of peaks in sunload. The algorithm is capable of finding all important local extremities of sunload.
• Decreasing the computational time. Adaptive seeking for variances in the sunload is much more efficient than the analysis on a fixed grid.
• Comprehensive result review. From the surrogate model, it is possible to generate sunload maps on various grid resolutions.