Engineering Analysis and Finite Element Analysis Consultancy
Overview

The CREA Consultants engineering analysis consultancy is intended to provide the client with:

  • A full analysis of a structure or plant item subjected to defined loading;
  • Project support in terms of advising the client on the execution of the client's own analysis;
  • Expert review of the client's own analysis at any level from an advisory review through QA checking to an in-depth independent technical assessment or peer review; or
  • Advice on the verification and validation of analysis.

CREA can also run analysis in parallel with the client's own analysis to provide a checking or scoping analysis, perhaps aimed at getting early indications of the outcome of the major analysis.

Capability

CREA has the in-house capability to offer a wide ranging engineering analysis services to clients; we are able to analyse most civil and mechanical engineering structures and components subjected to a wide and varied set of loading conditions. We also have a proven track record in applying multi-physics loads to structures, such as combining wind, wave temperature and mechanical loads.

Our analysis capabilities include:

  • Basic analysis of structures and components
  • Design optimisation
  • Virtual Prototyping
  • Advanced Analysis
    • Linear and Non-linear
      • Material
      • Geometry
      • Contact
      • Ropes
    • Dynamic (Vibration)
      • Frequency Domain
      • Time Domain
      • Hybrid (Mode superposition)
    • Thermal
      • Steady State
      • Time Varying
Loading and Physics

CREA's analysis capability covers many physical domains. However, our primary capability is to be able to apply and interpret loads due to extreme or hazard conditions. Our analysis resources are designed to efficiently handle complex loading regimes, and as such we aim to provide a cost effective solution. Two examples of our capabilities in this field came from the analysis of a floating docking facility and it's approach structures sited at the Clyde Naval Base in the UK. The structures are designed to withstand seismic loading, with the structures variously sensitive to near field and remote (long period motion) events. The need to bound soil profiles; consider varying water levels; use both the near field and long period motion input; and to consider design basis and beyond design basis loading resulted in sixty-six non-linear (contact and material) transient analyses being necessary. Efficient parametric design of the model and use of the extensive capabilities of the UNIX and LINUX operating systems allowed us to analyse and post-process the runs largely automatically. The second example is the analysis of a steel truss bridge structure serving the floating structure. In analysing this the vehicular loads added to the external variations describe above. This resulted in over three-hundred transient analysis passes; the input seismic loads being extracted from the previous analysis.

Our philosophy is therefore to use the computing resources to make the analysis process more efficient; allowing high fidelity results without the cost of assembling individual runs. This approach will very often result in a detailed analysis for the same price or 10% to 15% additional price than the solution of one single load pass.

Examples of loading considered:

  • Seismic

    Earthquake loading to structures can be analysed in several ways, the most cost effective is the modal response method. The transient response methods are used where there is a design advantage in doing so; the primary drivers being the need to pass on seismic motions to other disciplines; or the need to analyse non-linearities. These techniques are suited to all classes of structures including nuclear and process safety related facilities.

  • Soil Structure Interaction (SSI) and Structure Soil Structure Interaction (SSSI)

    The most complete seismic analysis process allowing the supporting soils to play an active part in the analysis of the structure. CREA offers different levels of SSI analysis to suit the project demands, however all start with scoping hand calculation.

  • Thermal

    Thermal or temperature loads cover a wide range of loading scenarios, from the simple atmospheric temperature variations, through process temperature to fire. Thermal loads impinge on a structure by various physical mechanisms and CREA has the capability and experience to cover most of these. It may be that the temperature distribution is known, for instance from an external analysis source, from a project specification or from a code requirement. Here the temperatures will be applied as external loads. In other cases it may be necessary to determine the temperatures in a structure or component. This is performed using either steady state or transient thermal analysis. The resulting temperatures will then be transferred to the structural model to derive the stress results.

  • Wind

    Wind loading on structures can be characterised as simple pressure loads (when the structure response frequency is well separated from gust frequencies), or as a power spectrum. CREA has the capability and experience to analyse both of these scenarios. The other major wind loading scenario is vortex shedding, which affects flexible structures such as towers, masts and chimneys. CREA has the capability to consider vortex shedding based on standard approaches, such as those presented in the various civil engineering wind codes. For higher order analysis where Computational Fluid Dynamics (CFD) simulation would be required CREA would partner with others.

  • Vibration

    Seismic loading is one particular aspect of dynamic loading, vibration loading can be seen as a "catch all" description as it describes a multitude of dynamic loading scenarios. Vibration analysis of structures can be seen a nuisance loading. CREA has the capability and experience to study many dynamic loading regimes including:

    • Plant vibration on buildings
    • Equipment vibration on pipelines and supporting structures

    The only real requirement is that the vibration can be characterised using power or response spectra, steady state vibration, or time-histories. Once characterised the vibration can be analysed within the structure or system of interest.

  • Impact

    Impact loading takes many forms and the solutions require very different tools. CREA has the capacity to consider those impact scenarios that do not lead to very large strain material responses. Otherwise the only real requirements are to be able to characterise the impact and having a clear view on the form of the outcome.

  • Blast/Explosion

    Blast and explosion response are clearly closely related and the terms are used interchangebly. The analysis techniques used to solve such problems will depend on the desired outcome and the type of load bing imposed. Often these loads are analysed using hand calculation as the inherent conservatism of the methods used leads to a design with a higher confidence. If the structure is complex, such as a blast wall, or if the material responses are of importance, then the Finite element Analysis method will be used. CREA has analysed the response of entire strucutres, such as an offshore oil production facility, local structures such as a fire.blast wall and items of equipment such as vessels and pipework.

  • Fire

    The response of structures and plant to fire is a case of combining thermal and structural analysis. A good way of analysing fire on any structure or component is to analyse the development of the structural temperatures with a thermal transient analysis and then to apply the resulting time-varying temperature profiles to the strucutre (but not necessarily as a transient analysis). If there is collapse or failure then this method will estimate the time to failure. It is interesting to note that large fires are oftem more survivable than smaller fires due to the stress distributions due to hot and cold areas of the strucutre.

  • General

    The loads described in the forgoing sections are all specialised in their nature. CREA will analyse any loading regime where either we have in-house experience in applying and understanding the loads, or the client can provide the interpretive experience.

Advice and Support

CREA is happy to provide expertise to analysis projects in support of the client's in-house capability. The input may be assistance with modelling or using analysis softwware, bolstering in-house quality assurance, or carrying out reviews and assessments to various levels. The clients in-house team may lack a skill or experience level that CREA can provide.

  • Analysis Advice
    • Advice on modelling structures, components and systems
  • Analysis Troubleshooting
    • Examining modelling that has failed to meet expectations
    • Expert witness with respect to FEA
  • Reviews
    • Project Reviews
    • Independent Peer Reviews (IPR)
    • Independent Technical Assessment (ITA)
    • Independent Nuclear Safety Assessment (INSA)
Using a Consultant

In any design project the capability of the team is the sum of the capabilities of the individuals in that team and the capacity of the hardware and software to be used. CREA's analysis only service allows design teams to buy in the analysis capability when it is required, without the overhead costs associated with supporting a full time analysis group. This is particularly valuable for advanced analysis, where the staff, hardware and software costs can be a burden if under-utilised. A consultant brings a full expertise, hardaware and software package to the project team. When the project is complete the consultant steps aside until the next opportunity arises. There is therefore no "requirement" to provide continuety.

As described on this page and our engineering consultancy page, a consultant will if necessary take an analysis project or sub project and complete the analysis task. The results can either be passed back to the clients for the design review, or CREA can review the analysis results. However, there are many cases where the analysis can benefit from the inclusion of design limits, here CREA will work closely with the design engineers to ensure that the model is set up as efficiently as possible. ANSYS in particular has the capability to take full account of the design requirements, including limiting stresses within the model definition.

It should be remembered that the consultant does not necessarily need to have detailed product knowledge, which almost by definition the client will have. A consultant can define an analysis model with the client's support, run the analysis, then work with the client to interpret the results. The consultant carries the analysis overheads, the client benefits from a reduced overhead.

Analysis Tools

One of our most valuable analysis tools comprises paper and pencil (or more often today MathCad). CREA's does not forget that the most important aspect of any analysis is understanding. In addition, there are many cases where hand calculation will provide a sufficiently detailed analysis of a product. Why build a complex analysis model when it isn't necessary?

Following hand calculation the CREA's analysis phylosophy is to build complexity, as the building process also buils understanding of the analysis and the results. Even if it is known that the analysis will require a non-linear transient, initial simple studies point towards what to expect from the final complex analysis.

MathCad aside, our principle analysis tool is the large scale multi-physics Finite Element Analysis suite ANSYS. We choose ANSYS because we have almost thity years of continuous use of the program. ANSYS is also a very versatile program and we can adapt it to solve many different problems.

We support all analysis with bespoke programming using FORTRAN, C/C++, UNIX/LINUX shell programming and more if necessary. A listy of the analysis tools that we use is to be found in the "About Us" page.


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2011 CREA Consultants Ltd, High Peak, UK
Last Updated 11 Jan 2011