ASOM Technical Reports
The need for solutions for kinematic systems in the automotive and engineering industry is constantly present while the requirements on development of appropriate multibar-systems are continuously increasing. In the meantime, the requirements are so complex that even experienced engineers need a great expenditure of time to generate solutions using ordinary CAD software. With ASOM, a software is now available which generates multibar solutions in a very short time. The developer is embedded into the synthesis process because of the interactive character of ASOM.
In automobile construction, four-bar hinges are well-established solutions for the task of guided opening of rear and front hatches. Requirements for a front hatch are, among others, a sufficient vertical and lateral rigidity, while occupying a minimal installation space at the same time. Forces resulting from the airflow towards the windshield are trying to lift the front hatch, i.e. they act vertically upwards. The elasticity of the system will in the worst case lead to oscillations of the hatch corners at high speed that can negatively impact the driving experience. To prevent this, the four-bar mechanism must be sufficiently rigid. This is one of the main requirements for the hinge system. Generally, a designer has to satisfy several opposing demands during the design process. To satisfy these demands while the available design time is reduced ever further, new strategies for the design of four-bar hinges have been developed in a joint research project. This lecture will present these new methods, which also encompass synthesis and computer-based optimization, by means of examples. In a computer-based design strategy, classical methods like the two- and three-plane design are used to determine valid hinge variants. The found variants are then rated with respect to well they satisfy the given catalogue of requirements and the best proposal is delivered to the designer. This way, the design process was shortened significantly while solution quality was increased at the same time.
In this presentation, it will be shown how to perform a kinematics design from specification to solution in real-time (i.e. during the presentation itself), taking as example the process of designing a passenger car's rear tailgate mechanism. Using this example, several methods of synthesis are presented (kinematic synthesis, force synthesis and geometric synthesis). It is shown that all of these can be solved virtually in real-time for the given type of problem. This includes taking into account the usual requirements and restrictions that are specific to work on car bodies. The example assumes the use of a multi-bar linkage with at least one energy storage element (e.g. a specific predetermined gas spring). It is also shown how the kinematic design solution interactively adjusts whenever the specifications are modified.
Optimization of the simulation of kinematic assembly groups for car bodies (hatches, hoods, doors, convertible roof systems) in the conceptual design phase, using highly interactive “multi-variant compressed-time simulations” in the kinematics software ASOM v7.