Power and Pressure Systems

This industry ranges from the relatively demanding safety-challenged nuclear power sector to the manufacturers of industrial pressure vessels. The industry is characterised by codes of practise which seek to embody contemporary experience and which to some extent have yet to be adapted to take account of modern CAE capabilities. Thus for example much design is by “rule” – although “design by analysis” is being introduced in some codes.

In this environment the role for analysis and simulation is the traditional one of post design demonstration of structural integrity. In common with many industries there are demands in various sectors (e.g. nuclear power) to extend the life of existing plant, while at the same time improving operational efficiency. These demands introduce particular challenges in respect of the characterisation of ageing material (where the ageing process can involve corrosion and material degradation, fatigue and irradiation) and how to treat the uncertainties that arise. In some sectors (notably nuclear) the end-of–life decommissioning process can be dominated by safety concerns and simulation plays an important part in developing the associated safety case. Again long term material behaviour and the characterisation of other epistemic uncertainty are important issues. There is considerable interest in probabilistic models in respect of the latter.

Currently FE packages have the capability to perform cyclic loading analysis for fatigue and have material models for creep. There are standard methods available to assess fatigue damage and creep damage but techniques for assessment of combined fatigue/creep damage, seen in long period load cycles, using FE analysis have not been standardised.

Also, different users have developed material models to take account of degradation due to irradiation or corrosion. The FE community will benefit if this information is exchanged. Of particular interest are damage mechanics models which can use the stress strain state predicted from an FE analysis to indicate material damage.

There is also the important issue of regulatory certification in areas such as the nuclear industry, including the movement of nuclear materials by transport containers and systems.

There is a need to identify specific methods for conducting analysis and methods of validation to reduce variation and uncertainty. Interest in future research includes topics such as fracture mechanics for life extension and  repair, analysis of welded and bolted joints and probabilistic analysis.

The business drivers include a need for the design by analysis, compliance with design codes and evaluation of limit loads. Barriers include difficulty with validation of FEA results, terminology, insufficient awareness of the DBA manual and difficulty with incorporation of empirical knowledge into the FEA.

Summary of the Project Findings relating to the Power and Pressure Systems Sector (as presented at the project review meeting in Malta, May 2005) (PDF Format)