As you may have noticed we've had a makeover! NGCC now has a brand new, easy to navigate website along side a redesigned newsletter which will be sent out quarterly.

We welcome feedback on either aspect and members are welcome to contact us with ideas for content and what membership benefits we can offer to help them.

The redesign comes 12 years since the network's launch in 2000 and marks a new chapter within the association.

Should you wish to contact us you can do so on ngcc@netcomposites.com or call +44 (0)1246 266246.

Fire Engineering for New-Build FRP Structures Event - 22/11/11

This event, organised through the NGCC R&D group, aimed to identify and discuss the key challenges in meeting fire regulations when using FRP materials in new-build structures.

Key issues raised:
Why is FRP held to a higher standard with respect to Fire? FRPs are still considered “new” materials in construction and existing guidance is often incorrectly applied to FRP elements and systems.

The fundamental goals of fire safety engineering are:
• Reaction-to-fire properties e.g. ignitability, combustability, spread of flame
• Structural fire resistance i.e. a measure of the survivability of a structure
In general, engineers, regulators and approving authorities only know how to apply prescriptive requirements – is there an opportunity for performance based design?

The overall aim of fire safety engineering is to limit the probability of death, injury and property loss. All modern codes place an emphasis on ‘life safety’ objectives by providing adequate means of escape and using compartmentation to contro the spread of fire.

There are three main failure criteria that define fire resistance for structural members: 
• Loss of load-bearing capacity
• Loss of fire separation characteristics
• Unacceptable temperature rise at various locations

Fire resistance is set out by codes based on:
• Time for occupants to escape
• Time for fire-fighters to carry out rescue
• Time for fire-fighters to surround and contain the fire
• Duration of a burnout of the fire compartment without intervention

Prescriptive fire resistance requirements are the backbone of passive fire protection in buildings and are based on decades of standard furnace tests on materials and systems. The requirements depend on the type of construction material and the overall structural system.

FRPs are combustible and it is the resin that causes most issues, but there are special systems, fillers and coatings that can be used to improve fire resistance. Properties such as strength and stiffness are most affected, particularly at temperatures near the Tg of the resin. Loss of interaction between individual fibre occurs causing decrease in transverse, shear and bond properties.

Performance based design is the way forward. Modern fire safety codes allow determination of fire resistance by ‘suitable’ calculations. There are three essential components:
• Fire Model (e.g. BS EN 1991-1-2:20021)
• Heat Transfer Model (discretion)
• Structural Model (rational understanding of material and full structural response)
 
Action: The workshop session highlighted several issues requiring further research.
It was agreed to form an NGCC working group on Fire Engineering to draw up a strategy and work plan to move things forward. There is a desperate need for a coordinated approach to ensure better marketing and dissemination to educate the construction industry and also to enable the development of collaborative research programmes.

More information: ngcc@netcomposites.com

Steni Panels Play the Lord of the Manor

Seven colours of rainscreen cladding panels from Steni UK have helped a new exemplar centre for the performing arts become a landmark for the community sooner rather than later.

The Colour panels, in colours ranging from dark rich red through to a light yellow, were cut to size in Steni’s factory to save time on site, then installed in a stunning harlequin pattern to emphasise the main body of the new Creative Media Centre at the MCE Academy, a specialist Performing Arts College in York.

One of only 17 in the country to receive grant aid from the Department for Education, the £3million BREEAM “Very good” centre was built by main contractor Hobson & Porter over eight months, linked to the 900-place former Manor CE secondary school that was built on an unused agricultural field just two years earlier.

Architects Morgan Lloyd Jones were unaware of Steni’s cut-to-size capability when they involved the manufacturer in a review of rainscreen cladding materials for the project. It was the sheer size of Steni’s colour range - 44 standard colours and three gloss levels - that originally impressed them.

Steni’s cut-to-size capability means that panel sizes from 850mm to 3,500mm can be cut automatically to length at no extra cost and in section widths at a nominal charge – a facility which is believed to be unique to Steni. All contractors need to do then is attach the panels to the fixing system, either by screws or structural adhesive.

At MCE Academy, some 700m² of 595mm x 595mm squares of Steni Colour panels, which are manufactured from fibreglass reinforced polymer composite with a smooth surface of 100% acrylic that is electron beam cured without the use of solvents, were screw fixed by specialist sub-contractor Farracrest.

Will Jones, of Morgan Lloyd Jones, said: “Steni’s ability to cut the panels in the factory is an ideal scenario for a multitude of reasons and was certainly one of the contributory reasons why we specified Steni.

“Not only does it minimise waste and time on site, which is something all contractors are trying to achieve, but from our point of view, this cutting facility provides quality reassurance knowing it has been accurately manufactured in the factory under controlled conditions.”

He added: “It would have been impossible, given the number of different colours we are using at the creative media centre, MCE, for the panels to have been cut anywhere but the factory due to the sheer scale of the operation and the accuracy required to achieve our design requirements.”

Morgan Lloyd Jones’ brief was to provide an exemplar arts and media centre on the 6.5 hectare site – a range of suitable spaces providing diploma courses in the performing arts and industry-standard creative and media facilities for 14 to 19-year-old students, community arts groups and other schools.

The main component of the 1,650m² building is a 200-seat auditorium designed for drama, dance and music. Two rehearsal/dance studios are adjacent to this space, with support spaces. There are also creative media spaces, an Apple computer training centre, conference room, and public spaces such as a gallery and seating areas.

The lightweight, 7mm-thick Steni panels clad the central part of the building - the auditorium and public spaces, better known as The Hive.

Will Jones said: “The planning department was very enthusiastic about the approach to the design. It was viewed as a landmark building in York due to its location close by the ring road. The visual appearance was an important consideration for both the image of the city and also that of the end user.

“They project the symbol of The Hive, an image full of vitality, busy movement, colour and artistry, mirroring the users of the building. They sell the building and its function, acting as a metaphor for the host of activities taking place in and around. Externally, they can be used as a backdrop for performances and as enclosures for social and recreational activities.”

He added: “The visual impact of the Steni panels is balanced by more neutral finishes to adjacent areas of the building. The rendered panels to adjacent building blocks are secondary to the central area but reflect the Steni-clad area via the colour hues used.”

Website: www.steni.co.uk

Projects to rebuild America's roads and bridges have many goals – improving safety, traffic flow, reliability, and maintainability, and getting the job done with minimal impact on existing traffic. A recent project to replace the east half of Washington's Hood Canal Bridge and widen the entire structure shared all of these goals and heightened the challenges for the Washington State Department of Transportation (WSDOT) and Parsons Brinckerhoff.

Projects to rebuild America's roads and bridges have many goals – improving safety, traffic flow, reliability, and maintainability, and getting the job done with minimal impact on existing traffic. A recent project to replace the east half of Washington's Hood Canal Bridge and widen the entire structure shared all of these goals and heightened the challenges for the Washington State Department of Transportation (WSDOT) and Parsons Brinckerhoff.Projects to rebuild America's roads and bridges have many goals – improving safety, traffic flow, reliability, and maintainability, and getting the job done with minimal impact on existing traffic. A recent project to replace the east half of Washington's Hood Canal Bridge and widen the entire structure shared all of these goals and heightened the challenges for the Washington State Department of Transportation (WSDOT) and Parsons Brinckerhoff.

At a total length of 8,000 feet with a floating portion 6,530 feet long, the Hood Canal Bridge is one of the world's longest floating bridges. Composed of east and west approach spans, transition spans, and floating pontoon spans, the bridge also has a 600-foot center floating draw span, which provides a navigation channel for U.S. Navy ships passing to and from Bangor Naval Base.

As the only crossing of the Hood Canal, the bridge is a vital component of the highway infrastructure for residential, commuter, and commercial traffic in the South Puget Sound region, with an average daily usage of 15,000 to 20,000 vehicles.

Moreover, any detour during bridge construction would require costly emergency ferry service.
Replacing the east-half floating section involved a complex marine operation that required closing the bridge, yet this process was accomplished in just 34 days, enabling the bridge to reopen to traffic eight days ahead of schedule. Prior to that, only two weekend bridge closures were required for replacement of the west and east approach spans. The existing west half of the floating section was widened using staged construction to maintain traffic over the bridge.

The east-half replacement was designed by WSDOT in partnership with Parsons Brinckerhoff.

Built in 1960, half destroyed in 1979

In 1960, the existing two-lane, 1.5-mile concrete floating bridge was designed and built to extend Highway 104 between Kitsap and Jefferson counties over Hood Canal, a 340-foot-deep fjord-like arm of Puget Sound. A floating bridge design was selected because the canal is more than 300 feet deep and has a tidal variation of more than 16 feet, ruling out a fixed bridge design.

The Hood Canal is subject to frequent storms off the Pacific Ocean that generate large waves and fierce winds. In February 1979, a storm destroyed the west half of the Hood Canal Bridge. Although the east half of the bridge survived the storm with minor damage, the loss of this critical link from Seattle to the Olympic Peninsula resulted in a 100-mile detour and activation of costly emergency ferry service.
Parsons Brinckerhoff was the lead firm in a joint venture for the reconstruction of the west half of the bridge. In 1982, the program was completed with a new floating draw span replacing the floating portion of the west half of the bridge.

WSDOT had the joint venture complete plans the following year for future replacement of the east half. However, because of funding limitations and a predicted remaining life of approximately 20 years, the east-half replacement was not undertaken at that time.

Fast forward: Upgrading the entire bridge

In 1998, WSDOT retained Parsons Brinckerhoff to update the existing plans and specifications for the east-half replacement based on lessons learned from the 1979 bridge failure. It was determined that the bridge roadway should be widened from 30 feet to 40 feet to accommodate two 12-foot lanes and two 8-foot shoulders to improve traffic flow and safety for motorists and bicyclists. The wider roadway was needed to accommodate traffic growth in the region.

Widening a fixed bridge is a familiar challenge to bridge engineers. However, widening a floating bridge to accommodate a wider superstructure with a higher dead and live load is a much more significant challenge because the floating bridge's capacity is limited by its buoyancy.

The project team developed the bridge-widening design concept that was able to accommodate the wider superstructure while accommodating the increased displacement requirements for the pontoons that support the substructure. WSDOT completed the final design plans for the widening of the existing fixed-approach spans, existing west-half superstructure above the pontoons, and the new east-half superstructure above the pontoons; as well as the new parallel chord pipe transition span trusses, which will minimize ongoing maintenance.
To minimize the added weight of the superstructure, lightweight concrete was used in the traffic barrier, diaphragms, and the roadway shoulder for widening on the west half. For the east half, a more efficient girder was used together with normal-weight concrete.

Parsons Brinckerhoff, in association with Streeter Associates, designed a new east control tower and storage building and new east and west generator buildings. The control tower building was designed with fiberglass-reinforced concrete panels to provide an attractive, lightweight, durable surface, and building panels and concrete surfaces are coated for uniform color and improved durability. Plans were also prepared for new electrical, control, mechanical, and hydraulic systems for both the east and west halves of the bridge. These new systems improve the reliability of bridge openings.

Design challenge:

Increase load and hydrodynamic resistance

Adding weight to a floating structure is a challenge in and of itself. But in this case, the design of the east half needed to accommodate an increased dead and live load while resisting a complex set of hydrodynamic forces associated with major storms – forces that had caused the earlier bridge to fail.
The replacement bridge was designed to withstand sustained waves generated by 83-mph winds and wind pressure from 110-mph gusts. The design team used computer modeling for static analysis and for structural dynamic analysis of wave forces. Adding to design complexity, all construction materials were required to withstand a highly corrosive marine environment.

The replacement floating bridge structures consist of continuously linked longitudinal concrete pontoons held in place by half-mile-long anchor cables attached to concrete anchors weighing 1,500 tons each. The prestressed concrete pontoons, anchors, and anchor cables are 2.5 times stronger than in the original 1960s design.
 

The rebuilt 8,000-foot-long Hood Canal Bridge in Washington has a 6,530-foot-long floating portion and a 600-foot center floating draw span.

Each pontoon weighs 8,300 tons and contains 36 watertight cells. The compartmentalized design of the east half, which is an improvement over the original design, keeps water from migrating in the event of cell flooding and improves safety should a ship strike the pontoons. Special submarine-type, screw-down hatch covers provide access to each compartment to facilitate inspections.

The pontoons – 10 feet wider and 4 feet deeper than the originals – support a two-lane roadway of 60-foot, precast, prestressed concrete spans. The roadway is supported on columns above the pontoons to keep it above storm waves and spray. The pontoons are post-tensioned vertically, longitudinally, and transversely. Precast segments were used in many of the west-half pontoons to speed construction while the east-half pontoons were almost entirely fabricated using cast-in-place construction.

Each lift-draw span combines a 300-foot-long steel deck and a floating draw span. To open a span, the deck is lifted hydraulically to create an open well into which the draw span is retracted beneath the deck. In addition to being more economical, the lift-draw design allows a safer and more efficient traffic flow than was possible on the original bridge, which required a sharply curved, split roadway to leave room for draw-span retraction.
The U-shaped pontoon structure for the draw span provides an open well into which the draw span can be retracted beneath the raised steel deck. When the draw span is extended, the deck is hydraulically lowered to roadway level. The draw span is operated by a rack and pinion mechanism with twin 432-foot-long rack gears. Both spans are electronically controlled from a single control house. This combination of hydraulic and mechanical drives with a floating, hollow, prestressed concrete structure involved a rare combination of civil, marine, mechanical, and electrical engineering.

The bridge construction also included a special hinged pontoon joint and flexible deck section. When dynamic analysis simulating storm forces showed high torsional moments about the pontoon joint at the draw span, the answer was a structural hinge: an 8-foot-diameter, steel-lined, concrete cylinder sliding on teflon-coated neoprene bearings within a steel-lined can – a "wrist" held together by cable. Across this joint, a flexible superstructure span of steel stringers with partially filled grating deck can twist with the pontoons yet maintain a smooth roadway.

The east half of the floating section was replaced in a complex marine operation that required closing the bridge. Of a total of 17 pontoons, all but three were fabricated off site in a graving dock; three pontoons that had been saved from replacement of the west half of the bridge in 1982 were retrofitted and reused. Ranging in length from 60 feet to 360 feet, the pontoons were outfitted with a new superstructure and assembled in units so that they could be floated into place.

At the same time, 26 new anchors were installed; and the existing east half of the floating section, including the east transition span, was removed. Finally, the replacement units were towed to the bridge site and anchored.
Since its reopening on June 3, 2009, the Hood Canal Bridge has provided motorists and ship traffic with improved safety, traffic flow, and reliability. The east-half replacement project earned a 2011 Engineering Excellence Award from the American Council of Engineering Companies of New York; it also was named Number 1 of the Top 10 Bridges of 2010 by Roads & Bridges magazine.

Website: www.pbworld.com

Pipex Wins a Prestigious IMeche Award for the Second Consecutive year

The Manufacturing Excellence Awards is the premier annual free award scheme for the UK manufacturing industry, supporting and honouring manufacturing success.  Run by The Institution of Mechanical Engineers for over 25 years, the Awards attract entries from manufacturing businesses in all sectors.

The assessment process for entrants involves completing an in-depth audit application.  Those who are successful at this stage then have onsite visits by a panel of business and manufacturing experts, who decide which companies progress to the next phase.

After the onsite visits the shortlist is announced and the companies who are chosen then go onto the final stage and  present to another panel of judges at the Institute Of Mechanical Engineers at Birdcage Walk,  London.
This years awards ceremony took place on the 23rd November at the Dorchester, Park Lane, London where compere Alistair Campbell – former Director of communications for Tony Blair announced the winners.

Pipex px® were proud winners of the Barclays Corporate Award for Financial Management
 
Pipex px® were also finalists in four other awards categories, Customer Focus; People Effectiveness; Business Development and Change Management; and Sustainable Manufacturing.

Tom Smith CEO of Pipex px® said:

"To be announced  as a "winner" of a  prestigious MX Award, and for the second consecutive year, is both a huge compliment and motivation for our business and our people, and validates our ethos to place "producing excellence" at the heart of everything we do. The owners, staff, suppliers & customers of Pipex px® are delighted to receive our 2011 MX Award, and sincerely appreciate the efforts of MX and IMechE in providing such a challenging yet inspiring process, by which to continually assess, benchmark and improve our business performance within the British manufacturing and engineering sector."

In 2010 Pipex px® were the proud winners of the Best SME at the Manufacturing Excellence awards and are one of only three companies to gain an award for a second consecutive year.
Stephen Tetlow, Chief Executive of the Institution of Mechanical Engineers commented :
“Pipex’s win is hugely encouraging for manufacturing in Plymouth and UK manufacturing more generally.
“The Manufacturing Excellence programme is not just about celebrating manufacturing success around the country, but about providing practical advice for businesses to support them on their journey during these difficult economic times.”

Website: www.pipexpx.com

LimesNet (Low Impact Materials and innovative Engineering Solutions research Network) is an EPSRC supported research network based at the University of Bath. It aims to build a community of researchers and industrialists that will lead to innovative research into materials and technologies that will significantly reduce the environmental impact of new and existing infrastructure.

LimesNet (Low Impact Materials and innovative Engineering Solutions research Network) is an EPSRC supported research network based at the University of Bath. It aims to build a community of researchers and industrialists that will lead to innovative research into materials and technologies that will significantly reduce the environmental impact of new and existing infrastructure.

LimesNet has awarded over £50,000 to its members for a first round of international missions that will support knowledge gathering from international centres of research excellence, build sustainable research partnerships and identify new challenges for construction materials research. The missions will follow up with workshops for network members to develop potentially transformative research projects. LimesNet will also host an international conference in Bath on the 12th and 13th July 2012 – a date for your diary.

Initially LimesNet will fund six missions supporting 30 members. One mission to Portugal and Spain, led by Dr Martin Ansell of the University of Bath, will work with researchers to develop innovative technologies utilising waste fibres in novel composite materials. Another mission, led by Prof. David Muir Wood of Dundee University, will travel to the Netherlands and USA to develop work on biological routes (bacteria) for the improvement of geo-materials.

Dr Julie Soden, a Reader in Textiles at Ulster University, is to lead a mission to North America to develop novel textile formwork solutions. Julie’s visit will include a visit to Prof. Mark West in Winnipeg, a leading expert in fabric formwork concrete structures.  Dr Jacqui Glass, Loughborough University, will be leading a mission to MIT in the USA to work on whole life cycle impact of cement and concrete structures. Her visit will include workshop sessions with leading experts in low carbon concrete solutions from across North America.

Dr Tim Stratford, University of Edinburgh, will lead a team to North America to develop collaborative working on low impact concrete structure through efficient structural form. Improving efficiency of concrete elements, such as beams, columns and floor slabs, will lead to significant materials savings and carbon reductions. Concrete is the second most consumed material by humankind after water, and worldwide the production of cement alone is responsible for some five to ten per cent of all carbon emissions.

Lightweight high strength fibre reinforced polymer (FRP) structures have been common place in the aerospace and automotive industries, but are still rare in structural engineering. Dr Mark Evernden, University of Bath, is intending to lead a team to France, Switzerland and Italy to learn from leading multi-disciplinary experts working with FRP.

Professor Walker, LimesNet Principle Investigator, said: “The international missions are an exciting opportunity for UK researchers to collaborate with leading experts worldwide, providing basis to develop transformative research on construction materials and technologies. Following the missions we will host workshops in the UK for members to further develop their research within a multidisciplinary community comprising a large number of leading industry stakeholders.”

LimesNet membership comprises over 100 leading researchers and sector stakeholders, including product manufacturers, building designers, contractors, and clients. The network is now seeking to recruit research members who generally work outside the traditional fields of construction materials to develop multidisciplinary solutions for challenges of low carbon construction materials and technologies. 

Membership of LimesNet is free; anyone interested is encouraged to contact LimesNet for further details.

LimesNet is supported for 12 months by the Engineering & Physical Sciences Research Council (EPSRC). Initial membership is much larger than similar research networks, comprising researchers from over 30 leading UK universities.

Non-academic membership is drawn from across the construction sector including material and product manufacturers; ground and structural engineering consultants; construction contractors and subcontractors; architects and building environment engineers; and clients, property owners and procurers. Members at the workshop included representatives from: Arup, Buro Happold, Carillion, CIRIA, Expedition Engineering, Forestry Research, Ibstock, Kier, Mineral Products Association, NHBC, Ramboll, and URS Scott Wilson.

Interested individuals and organisations from a wide range of backgrounds, with the potential for developing collaboration within the construction industry, are encouraged to contact LimesNet Network Coordinator, Eloise Spark at e.spark@bath.ac.uk.

Freyssinet Appoints Repairs Manager for London and the South East

Freyssinet Limited is pleased to announce the appointment of Gary McKenzie as their new Repairs Manager for London and the South East.

With over 30 years experience in the industry, and extensive knowledge in all aspects of concrete testing, survey and repair, Gary was the perfect candidate to assist Freyssinet in their ambition to initiate a local proximity network in London in order to capitalise and better service the southern market.

Freyssinet is already well established within the repairs market, particularly in working on highways infrastructure throughout the UK. Their wide range of skills and technical expertise are transferable to new and developing market sectors.

Freyssinet offers proven solutions for the repair, reinforcement and protection of structures. Their unique approach blends years of hands-on experience with expertise at the cutting edge of engineering. With practised designers, a corrosion consultancy company and hydrodemolition team all available in-house, Freyssinet is continuing to grow and develop, despite recent economic conditions.

Website: www.freyssinet.co.uk

New Training Courses for 2012

Having updated the UK’s National Occupational Standards for Composites in 2011, Dark Matter Composites Ltd (DMC) has taken the opportunity to update its training course content accordingly along with new courses to meet the demands of industry for 2012.

 

Resin Infusion & Light RTM
Considering the current requirement to reduce costs, improve quality and exposure limits/concerns relating to styrene, the new ‘Resin Infusion & Light RTM’ course includes the full range of infusion technologies and low cost closed moulding technologies in a one week intensive course.  As industry sectors such as marine recover and general industry grows in its use of composites, this course is ideally placed to address current and future industry needs for low cost consistent composite products.

Advanced Composite Repair
With the increased use of composites and the need for acceptance of structural composite repairs, Dark Matter Composites have revised their ‘Repair of Composites’ course and introduced an ‘Advanced Composite Repair’ course.  Composite repair is often an afterthought or conducted as a maintenance activity, whereas Dark Matter Composites considers it as a process in its own right.  It is a multi-disciplined process that requires extensive control to ensure reliability.  Key process stages such as dust generation/control, surface preparation, material identification and laminate specification are often taken for granted.  However, this is not necessarily the case and Dark Matter Composite’s cross sector course highlights and addresses these issues.

Laminate & Tooling Design
The move from metal to composite parts across a number of industry sectors, as well as the continual advances within the composites industry, requires accelerated training in order to address shortfalls in the experience of personnel.  Over the last 5 years Dark Matter Composites engineers and designers course has proved to be the most widely used and accepted course to fulfil this need.  To meet industry needs, the ‘Laminate and Tooling Design’ course follows on from previous courses.  Delegates address further issues relating to composite engineering by applying key theory to design problems to achieve solutions in a structured manner.  For those familiar with the pre-requisite courses, the new course sets the bar even higher.

‘Anticipating industry needs keeps us at the forefront of composite training.  The level of investment required to develop and run these new courses in terms of technical content, course structure, tutor training and tooling is extensive, but it is an investment that we are committed to which makes our provision world class and second to none.’ Rodney Hansen, Managing Director, Dark Matter Composites.

Full course information is available on the company website www.darkmattercomposites.co.uk. 

 

IDAC performs CFD and Structural FEA Analyses on a Pump Case

Background

IDAC’s client Hayward Tyler was required to design and provide a pump casing which was able to withstand a temperature increase of 56ºC in 3 seconds.  The casing was for a 500MW double discharge pump used to circulate water into a boiler, being used in the power generation industry. 

Hayward Tyler designed a pump for this application and as a part of the design process required IDAC to carry out Computational Fluid Dynamic (CFD) analyses and subsequent Finite Element Analyses (FEA) in order to verify that there would not be any excessive stresses in the structure due to the thermal stress and the internal pressure of 211bar.

This required a Fluid Structure Interaction (FSI) solution to be performed.  The ANSYS range of products allows the interaction between fluids and surrounding structures to be solved.  Products within the ANSYS Suite can be combined to perform one-way and two-way FSI.  For the purpose of this project a one-way FSI solution was carried out.  ANSYS CFX was used to carry out the fluid/thermal analysis and this was followed by an FEA analysis carried out in ANSYS/Mechanical in order to obtain an accurate stress solution.

Analysis

The pump casing was made of carbon steel, and the branches of the pump were connected to pipes. The geometry of the pump-motor assembly along with the sealing gasket between the pump and motor was supplied by Hayward Tyler as a single 3D model STEP file.

The CFD model was created by importing the 3D geometry into ANSYS DesignModeler and creating a volume of ambient air around it. For the FE model, fine details deemed to be inconsequential to the analysis were removed from the geometry, in order to produce a more efficient mesh.

The pump inlet and outlet pipes were extended at either end to ensure an adequate representation of the natural convection flow around the assembly, and also to accurately capture the axial stresses in the pipes.
The geometry was meshed with 3D tetrahedral elements for both the fluid and the structural regions using ANSYS Workbench version 13.0.  The graphic to the left shows the mesh used. The areas near the external air and pump interface were locally refined to obtain a high density of elements leading to an accurate resolution of the heat transfer coefficient calculated at the pump walls.

The design temperature of the pump was 370ºC and the design pressure 211bar.  The pump could be subjected to situations when water (maintained at temperature of 367°C) sat inside the pump for weeks together. Hence the internal walls of the pump were given a boundary condition of the water temperature instead of modelling the water flow through the pump. The objective of the analysis was to check the stresses on the branches of the pump case at the design condition. As the pump was located at a place where there would be just still air around it without any externally driven (fan) cooling, the external heat loss was only through natural convection. This was modelled within ANSYS CFX.

The project was split into two stages as follows:

1. The first stage involved solving a thermal analysis within ANSYS CFX, where the analysis type was considered to be steady state, incompressible, thermal, single fluid CFD analysis including heat transfer through the solid components of the assembly.  The ambient air fed into the fluid domain was set at 40°C. However, the local air temperature in the domain would vary depending upon the heat gained from the pump-motor assembly. A fixed temperature of 367ºC was set for the inner wet surfaces of the pump wall. The analysis calculated the temperature distribution through the casing wall and the convection film coefficient on the outer surfaces. 
The graphic to the right top shows the temperature distribution on the outer walls of the pump.

2. The second stage used the thermal results from stage 1 of the solution in an FEA model in order to accurately obtain stress results.  The temperature distribution derived from the first stage CFD analysis was imported and applied to the body as a load along with the internal pressure load of 211bar on the inner wet surfaces of the pump walls.

The analysis type considered was a steady state analysis with stresses being computed both due to the thermal load as well as the pressure load on the pump walls. The graphic to the right bottom, shows the equivalent stress distribution.

Linearised stress distributions were obtained in critical locations and the radius of the pump casing was also changed by Hayward Tyler in order to see its effect on the stress distribution and hence lead to a better design of the pump casing.

It was concluded from the analyses that the design requirements to increase the design ΔT of 56ºC in 3seconds for the pump casing, met the design criteria. Over the life cycle of the pump it was found to be fit for purpose.

Design Benefit

Rupert Knowles of Hayward Tyler says: “Working with IDAC has enabled us to complete a complex and detailed analysis which met the design criteria.  We have used IDAC on a number of occasions over the last six years, and have always been pleased with the response and performance of IDAC.  We have always been confident with the output received from IDAC which gives credibility to our designs.”

Website: www.idac.co.uk