Simulation information - standardising data for modelling and simulation
The automotive industry is changing from a computer-aided design (CAD) approach, concentrating on product geometry, to a computer-aided engineering (CAE) approach, using analysis software to simulate expected performance. The European Thematic Networks, FENET and AUTOSIM, have, however, identified a lack of suitable materials data as an obstacle to the wider adoption of CAE in advanced engineering. Data representations that can be directly processed by the analysis and simulation software is required, as well as information that is authenticated to offer reliability and confer confidence in its use.
Such technical facts are an asset, and they have to generate a return on the cost of producing them. The problems of collecting and collating such relevant materials data are that the information is often incomplete and cannot be augmented from other sources. Most of it is used for short-term knowledge creation, so archiving is not practical.
Engineering principles need to be followed for the production and management of technical information to ensure that it is fit for purpose – information engineering. This includes established engineering practices for quality control and quality assurance to ensure records are standardised.
Standards for computerised representation and exchange of engineering data have been developed by the ISO TC184/SC4 Committee over the last 20 years in a global collaboration between the world’s manufacturing nations and sectors. These specifications will enable the management of product data and lifecycle information. Two families of standards are important for developing such resources in simulation and modelling:
• ISO 10303 Standard for the Exchange of Product (STEP) – a complete and unambiguous description of each unit of a manufactured product throughout its lifetime. This measure provides structure and meaning for product information using key models.
• ISO 13584 Parts Libraries (PLIB) – resources for reference dictionaries to constrain the meaning of terms and their definitions. These dictionaries can be referenced directly from the STEP standards.
The most recent addition to the STEP family of product data standards is ISO 10303-235. Conceived initially to meet the needs of the aerospace industry, Part 235 has been developed to achieve computerised representation of any property measured by any technique. This universal regulation is possible because of the general power of the resources of STEP and the capability of the PLIB dictionaries to name and define the test methods used and properties measured for any particular application domain.
Part 235 is based on ISO 10303-45 Materials that first established materials data representation in the STEP family of standards. ISO 10303-45 defined materials data as, ‘a property of a product, provided representations of the composition and structure of the product, ensured that the property value is accompanied by the data environment to establish its validity and by the uncertainty on a value to provide its reliability’.
The recent edition of Part 45 extends this capability to represent property values by the mathematical expressions needed for analysis and simulation, and also enables composition values to be described by mathematical expressions such as <, >, a+b<c. The uncertainty and reliability of the expressions can still be defined.
Some of the scope of ISO 10303-235 is shown in the table to the left. It specifies the processes involved in the measurement of technical properties and their results, alongside decriptions of the administrative and technical resources required to provide an audit trail for any subsequent analysis of product failure.
Dealing with data
The implications of such information management include data independence from proprietary systems, re-usability of resources without the expense of re-work, data integrity throughout the production cycle, data longevity and stability throughout the lifecycle of a product, increased return from R&D, and limitation of legal liability.
The benefits of using the structures set by ISO 10303-235 are – inclusion of the data exchange capability, integration of resources between dispersed sites and stages of design and manufacture, information represented to the same standard can be combined, and there is still the freedom to use existing management systems with standardised access interfaces.
Environmental results and nuclear de-commissioning
The benefits of standardised data representation and exchange also extend to other increasingly important areas such as the environment. This is because:
• Environmental data have to be conserved for longer than the lifetime of any computer system or software application.
• The data have to be shared and exchanged between many different organisations with varying systems and applications and alternative methods of working.
• The information needs to be used and understood by systems at unknown times in the future.
For nuclear de-commissioning, resources need to be stored pertaining to the disposal of radioactive components for possibly millennia, or at least longer than the lifetime of any conceivable computer system. This data must also be in a form that can be accessed by future systems. Conserving the specifications for data representation, as well as the data values themselves, is necessary for this to be achieved.