Mechanical Engineering

What happens to a structure when exposed to loads that vary in time? That is what the subject of structural dynamics is about. The structure in question may, for example, be an aircraft, a car, a house or a bridge. The load, which varies over time, can arise when an aircraft makes a manoeuvre, when a vehicle drives over a road bump or when someone walks on a bridge, but the source may also be wind, earthquakes or vibrations from a machine.

The response, that is, how the structure moves and the stresses that are created, depends on a combination of the structure's construction and the load. An unfortunate combination can cause lower precision in a manufacturing machine, discomfort to passengers, high noise levels, and shortening of the useful life of the structure in a controlled way, but may also result in breakdowns with devastating consequences.

In order to prevent or control these processes, knowledge about the dynamic behaviour of the structure needs to be learned. Either you rely on measurements or on calculation models. Increasing focus is on calculation models, as they can be used in the early stages of the product development phase, as they allow investigation of processes that can be dangerous to perform in reality, and as they are generally cheaper than measurements on prototypes.

However, the models used must be validated – checked to match the dynamic behaviour of the actual structure. If the model is not satisfactory, measurement data can be used to calibrate, i.e, improve, the model.

Good knowledge about modelling and validation through vibration testing saves money for companies and may also be a prerequisite for being able to compete, as product development in industry is moving faster and faster.

Both experimental and analytical research

The research in the domain of structural dynamics at Linnaeus University is about modelling, vibration measurement, validation, and calibration and is carried out in collaboration with companies and other universities. We do research both experimentally and analytically.

One of the research domains is the dynamics of wind turbines, where we have started by studying the rotor blades of the turbines. A finite element model has been created to describe the dynamics of the blades. Data from vibration and material tests have been used to correlate and calibrate the model, which will be used for further research. The research also includes calibration in nonlinear structural dynamics. This is done in a research project together with Saab and Chalmers University of Technology.

The research in structural dynamics at the Department of Mechanical Engineering has a close collaboration with the Department of Building Technology and with RISE (Research Institutes of Sweden).

Some of the research in the domain of terotechnology has been focused on identifying and modelling relevant information – such as lost revenue, breakdowns, production and production time, costs due to poor quality, maintenance costs, fixed and variable costs, storage and spare parts, etc. – needed to achieve the results you desire. But besides that, terotechnology can also be used in the design of new production processes, to establish an effective integration between, for example, production, quality, maintenance and production logistics. The target is then decreasing overlaps, frictions and losses, and thus lower lifetime costs (LCC).

A result of the research within the subject is MDSS, a software that will help companies reduce financial losses. This is done by mapping the production and maintenance process, following up, analyzing and controlling its results, as well as estimating the financial benefits of the maintenance in order to increase the performance of the maintenance and the production.

Research in Product Development (PD) and Design Theory and Methodology (DTM) gives an opportunity to deep and detailed gain insight into the advances in engineering design and product development research and practice. These areas combine skills and knowledge at the core of engineering design and use advanced methods and tools which are leading on an international level. The goal is not only to develop new theoretical models, but also to study their applicability in the industry and education. The field of DTM has attracted attention of academic researchers and yielded a considerable number of results.

The main topics in our research are:

• Design theory and other disciplines: engineering sciences, material science, data science and so on.
• Design theory and industrial practice.
• Design theory and education.
• Engineering design and product development theories and tools: Conceptual phase of product design; Product architecture modelling; Modular product development; Robust design methodology; Tolerance and quality engineering; Sustainable development and LCA; Sustainable systems design.

The goal of this research is to build a reliable "bridge" between theory, research, education and practice in the field of PD and DTM.