A Methodology for Efficient Conceptual Design Analysis of Nonlinear Dynamic Structural Systems

There is a typical requirement conflict between fuel consumption and noise and vibrations in passenger cars. Obviously the combustion engine is a major source of vibration and has an influence on vehicle emissions. Similar properties apply to the power transferring mechanical driveline system. Many driveline design concepts that aim to reduce carbon-dioxide emissions intensify and add new vibration problems, since the majority of them affect vibration sources or system damping. In conceptual design of drivelines, many possible concepts proposals are studied in parallel. This situation calls for modelling and analysis that can meet the demand for rapid virtual prototyping. Conflicting to this is the trend in which models have become extremely detailed to meet demands from others than conceptual designers. The complex behaviour of the driveline system in combination with often highly specialised component models result in system models that at their best are valid only near a few specific stationary operating points. This makes is difficult to study the effectiveness of possible component design changes in early development phases. Instead, this is first revealed during system verification testing, when fundamental design changes since long are unrealisable.This work focus on models for conceptual design, \emph{i.e.} models that are not overparameterized. The aim is to find the balance when models are as simple as possible but as accurate as required by conceptual design studies. A methodology is proposed, based on knowledge of existing automotive methods and workflow, that with provided modelling tools has the potential to serve this purpose within the nearest future

Characterisation of Nonlinear Structural Dynamic Systems in Conceptual Design

The engine and driveline systems of passenger cars generates and distributes the necessary driving power and are major contributors to vehicle emissions, noise and vibrations, etc. More environmental friendly technologies under development are expected to intensify and add new comfort related problems, since most of them affect vibration sources or system damping. A successful balancing of fundamental system qualities requires a better use of simulation in early design phase. This work focus on virtual tools for analysis of low-frequency structural dynamic vibrations. In conceptual driveline design, many possible system solutions are studied in parallel and their often nonlinear behaviour requires robustness evaluation across full operating and design parameter ranges. This situation calls for virtual methods that are generally valid and meet the demand for rapid prototyping. Thus, models need to be as simple as possible and as accurate as required for capturing phenomena that occur in real drivelines. Further, analysis tools must efficiently process data sets from extensive parameter variations and extract fundamental system characteristics that can be used to reliably rate competing proposals. For this, a complementing design analysis methodology is proposed that improves current automotive development tools and workflow. A general and over-parameterised multi-body system model is constructed from detailed linear structural and schematic nonlinear parts. State-space reduction methods are then applied to modal components to balance prediction accuracy and evaluation speed of resulting conceptual design models. Parameter variations in fully known system models are simulated under ideal periodic loading and low noise conditions. A feature based frequency analysis approach is used to extract precise system characteristics and sort responses into qualitative classes. To efficiently process large amounts of generated data, statistical learning methods are used to automate the response classification

A Methodology for Efficient Conceptual Design Analysis of Nonlinear Dynamic Structural Systems

There is a typical requirement conflict between fuel consumption and noise and vibrations in passenger cars. Obviously the combustion engine is a major source of vibration and has an influence on vehicle emissions. Similar properties apply to the power transferring mechanical driveline system. Many driveline design concepts that aim to reduce carbon-dioxide emissions intensify and add new vibration problems, since the majority of them affect vibration sources or system damping. In conceptual design of drivelines, many possible concepts proposals are studied in parallel. This situation calls for modelling and analysis that can meet the demand for rapid virtual prototyping. Conflicting to this is the trend in which models have become extremely detailed to meet demands from others than conceptual designers. The complex behaviour of the driveline system in combination with often highly specialised component models result in system models that at their best are valid only near a few specific stationary operating points. This makes is difficult to study the effectiveness of possible component design changes in early development phases. Instead, this is first revealed during system verification testing, when fundamental design changes since long are unrealisable.This work focus on models for conceptual design, \emph{i.e.} models that are not overparameterized. The aim is to find the balance when models are as simple as possible but as accurate as required by conceptual design studies. A methodology is proposed, based on knowledge of existing automotive methods and workflow, that with provided modelling tools has the potential to serve this purpose within the nearest future