lightweight ambulance report 2015 - … · by working from a clean sheet of paper ... as such felt...

T h e D e v e l o p m e n T a n D T e s T i n g o f a l i g h T w e i g h T

a & e a m b u l a n c e

© Niche Vehicle Network 2015

T H E D E V E L O P M E N T A N D T E S T I N g O F A L I g H T W E I g H T A & E A M B u L A N C E

partners

Oughtred and Harrison Facilities Ltd

J & A Kay Ltd

Panel Systems


Table of contents1 Introduction .............................................................................................................................................. 3

1.1 Project Objectives ...................................................................................................................... 4

1.2 Project Partners.......................................................................................................................... 4

1.2.1 Oughtred and Harrison Facilities Ltd............................................................................. 4

1.2.2 J & A Kay Ltd ................................................................................................................. 4

1.2.3 Panel Systems .............................................................................................................. 5

1.3 Project Scope ............................................................................................................................. 5

2 Project Delivery ....................................................................................................................................... 6

2.1 Concept Layout and Ergonomic Evaluation ............................................................................... 6

2.2 Construction Method Evaluation ................................................................................................ 7

2.3 Physical Testing of Sub Components ....................................................................................... 12

2.4 Doors Hinges and Latches ....................................................................................................... 13

2.5 Front Bulkhead ......................................................................................................................... 15

2.6 Offside Structural Layout .......................................................................................................... 16

2.7 Nearside Structural Elements................................................................................................... 16

3 Summary & Conclusions ....................................................................................................................... 17

3.1 Future Work .............................................................................................................................. 17

3.2 Acknowledgements .................................................................................................................. 18


© Niche Vehicle Network 2015 3

1. introductionuK Frontline Ambulances carry the technically advanced equipment in the world. The ambulance crews and the equipment they carry are focused on stabilising persons at the scene. This vastly increases the survival rate. This means uK ambulances carry a lot of equipment with an ambition to carry more. unfortunately using our current design we have now reached the gross Vehicle Mass of the Fiat Ducato van on which the ambulance conversion is based.

A number of O&H’s existing customers have expressed interest in the lightweight A & E vehicle concept as the expected reduction in fuel consumption would result in significant running cost savings.

The new design is a direct replacement for the existing model, of which O&H sells approximately 100 examples per annum. It’s hoped that the lightweight ambulance will also garner significant interest from healthcare trusts not currently working with O&H and, thanks to whole vehicle type approval, new clients based in the European union.

The present offerings in the market from both O&H and its competitors have evolved over time to incorporate a number of additional customer and regulatory requirements such as equipment storage, hygiene and crash testing. As a result the ambulances have become heavier, the handling has been compromised, running costs have increased, fuel economy has decreased and, crucially, emissions have increased. By working from a clean sheet of paper to reduce vehicle interior weight, O&H can address these market failings and offer a significantly better solution to both its existing and potential clients.

In addition the Care Quality Commission (The independent regulator of health and social care in England) suggests that the front line ambulance in many cases is people’s first contact with the NHS system. And as such the environment presented inside the ambulance should reflect the sterile environment of an operating theatre. The CQC also suggest the interior should be “easy to clean” to reduce possible transmission of infections such as RSA.

The purpose of this project was to develop a workable solution for a lightweight, cost effective accident and emergency ambulance in order to reduce vehicle emissions, improve fuel economy, and reduce running costs whilst meeting legislative requirements.

The present offerings in the market from both O&H and its competitors have evolved over time to incorporate a number of additional customer and regulatory requirements such as equipment storage, hygiene and crash testing. As a result the ambulances have become heavier, the handling has been compromised, running costs have increased, fuel economy has decreased and, crucially, emissions have increased. By working from a clean sheet of paper to reduce vehicle interior weight, O&H addressed these market failings and offer a significantly better solution to both its existing and potential clients.

O&H is proud of its reputation for safety and, as such felt that a significant programme of research and development would be required; comprising both computed aided analysis and physical testing, in order to ensure the end product is built to O&H’s exacting standards and most importantly, that it is safe.


1.1 project objectives• Thorough understanding of Materials.

• gain Virtual and real life Crash Testing Experience.

• 100Kg Total Weight Saving.

• Create a modern environment similar to that in modern A & E departments.

• Eliminate dirt/bacteria traps and design for easy cleaning.

• Cost Reduction (2-5%).

• Maintain and improve ergonomics.

• Consider specification features of key customers including West Midlands Ambulance service, East Midlands Ambulance service.

• Minimise number of panels used to form vehicle interior thus reducing number of panel joints.

• Modular design including pre-defined options and allow sub assembly of Bulkhead, Roof, side walls.

• Minimise modifications to OE vehicle structure.

• Must be compliant to BS EN 1789:2007 - Medical Vehicles and their Equipment - Road Ambulances.

• Investigate availability of materials with antibacterial properties.

• All materials in construction must be 100% recyclable.

1.2 project partners1.2.1 oughtred and harrison facilities ltd O&H Vehicle Conversions (the trading name of Oughtred and Harrison Facilities Ltd) are one of the leading vehicle converters in the uK. O&H Vehicle Conversions have been an established converter since 1988, specialising in Patient Transport Service (PTS) ambulances, front line A & E ambulance vehicles, Wheelchair Access Vehicles (WAV’s) and Welfare vehicles. O&H main customers are the 13 uK ambulance trusts, private ambulance operators, local councils and Motability operations. O&H are also proud to be partnered with the Independent Ambulance Association (IAA) and support them wherever possible.

The O&H engineering team were responsible for the ambulance interior design and all sup components from concept to completion. As project leader, O&H assigned a dedicated Lead Project Engineer to be responsible for day to day management of the project and to ensure the identified plan is adhered to. The Lead Project Engineer was also responsible for ensuring that the assigned resources within O&H, J & A Kay and Panel Systems meet the identified project milestones.

The programme of work was led by O&H Vehicle Conversions who are one of the key players in the vehicle conversion industry. O&H have identified a requirement for an improved ambulance product as a result of feedback from both existing and potential new customers.

1.2.2 J & a Kay ltd J & A Kay Ltd held responsibility for engineering designing and manufacturing moulds. The moulds were then used by J & A Kay to manufacture the moulded panels. J & A Kay also provided the components for prototype testing. J & A Kay have experience in thermoplastics and the latest manufacturing technology. J & A Kay provided quality components made via Plastic Forming - Thermoforming, Vacuum Forming, Drape Forming, Press Forming, CNC Trimming, and plastic fabrication in ABS and polycarbonate.

J & A Kay also provided advice to the O&H design team on the design and manufacture of thermoformed components including limitations in manufacture and possible design improvements. J & A Kay Ltd dedicated one Engineer to assist with the design of tooling and advise with regards to design for manufacture for the duration of the project. The Engineer reported to the O&H Lead Project Engineer on a weekly basis to advise on progress throughout the project.



1.2.3 panel systems Panel Systems is the exclusive uK Distributor of Thermhex polypropylene honeycomb cores and manufacturer of Thermhex composite panels. A strong, light material, Thermhex is used for the production of lightweight construction components in a variety of applications and industries, ranging from car parts to furniture and fibreglass swimming pools. Panel systems introduced the project team to a new generation of polypropylene honeycomb cores now available from new producer Thermhex. The use of a Sandwich structure using honeycomb core enabled significant weight reductions in components. The resultant energy savings will help to end user lower their carbon footprint and the minimized fuel consumption helps to build a more sustainable business.

Panel systems offered a comprehensive CAD design service, which included accepting partners own drawings in a range of file formats and producing a workable panel or component to meet the bespoke requirements. Their in-house CAD/CAM facilities ensured they provided rapid prototyping to suit partner’s needs and undertook both large and small production runs. This expertise was invaluable when the O&H design team begun to work with their new generation of Polypropylene honeycomb core panel technology.Panel Systems extensive facilities include two large CNC machines and sophisticated sanding equipment, which offered a close tolerance machining service to the other project partners. Panel Systems also offered experience of the design and manufacture of sandwich panels to meet a wide range of performance criteria not available in current single material structures.

1.3 project scopeThe project aims to combine 3D CAD design, Finite Element Analysis techniques and physical testing of subsystems to verify that the proposed, novel, fully moulded plastic honeycomb panelling system will be suitable for its proposed purpose which is to form the vehicle’s interior structure. It should also prove that the composite panelling system is able to meet the required 150kg weight saving.

The existing O&H Fiat Ducato based ambulance has been approved by the VCA and associated approval documentation shows the ambulance emits 287g/CO2 per km with an urban cycle fuel economy figure of 10.9L/100km (EC Type Approval No: e11*2007/46*0844*01). On average, an ambulance travels around 100,000km per annum and O&H has so far built 109 vehicles. Each vehicle will therefore produce 28.7 tons of CO2 per year which equates to 3130 tons per year for the entire fleet. The specific aim of this programme is to reduce the converted vehicle weight by 150kg in order to obtain an improvement in fuel efficiency of 3% (Cenex, December 2012), a reduction in CO2 emissions of 10gCO2/km (Cenex, December 2012) and a combined fleet total of 100 tons CO2/yr.

The final output of the project is a thorough understanding of the new design the materials proposed and the required manufacturing techniques. It will also prove that the prototype design meets cost and weight targets and confirm that the interior is strong enough to withstand a 10g impact as per the European regulation number EN 1789.


2. project DeliveryThe programme of work was led and managed by the Lead Project Engineer allocated to the project at O&H Vehicle Conversions and in accordance with the project plan. The overall objective of the project is to deliver a viable design solution for a lightweight A & E Ambulance. The first stage was to agree the layout with the management team and potential customers. The next stage was to evaluate construction methods though manufacture of sample lockers. Then go on to perform physical testing of sub components to ascertain structural integrity. The plan was split into key areas of the vehicle interior, starting with the front bulkhead and working around the vehicle to define all the hard points such as cupboard and seat locations. These items are classed as subassemblies, as follows:

• Concept Layout and ergonomic evaluation.

• Construction method evaluation.

• Physical testing of sub components.

• Doors hinges and latches.

• Front Bulkhead structural elements.

• Offside structural elements.

• Near Side structural elements.

Each subassembly was referenced in the plan as a milestone and split into subtasks; initially starting with the general concept for the layout. This concept work took 3-4 weeks for each area. Priority was given to the load bearing, long lead time subassemblies, specifically the Front Bulkhead, OS Rear Cupboard, NS Rear Cupboard, OS Top Locker and NS Top Locker which will be designed in parallel by a team of three O&H engineers. This concept work was performed in 3D CAD along with 3D models of the Ducato chassis which were already supplied by the FIAT for a previous project. Once completed, Steve Hammond conducted initial FEA analysis in conjunction with conventional hand calculations to prove out the design prior to manufacture. At this stage the design approach was aimed at a conservative factor of safety Figure (5) with a view to ensuring that the crash test provides data which is both useful and representative. A further two week period was allocated to each sub-assembly in order to allow for design corrections and refinements prior to building the prototypes.

2.1 concept layout and ergonomic evaluation



Work Completed 18.09.14, elements agreed: 1. Cupboard Sizes

2. Seating positions

3. Equipment Layout

2.2 construction method evaluation


evaluate:

• Design Suitability

• Supplier Communication

• Construction Method

• Construction Weight

• Construction Strength

• ease of use

• Suitability

• Repeatability

lessons learned:

• BIB Option too Complicated with no Signature Advantages

• Big Learning Curve for J&A Kay

• Ease of use - Door Mechanism Needs Work

• Suitability - Excellent Weight, Strength and Cleanliness Characteristics

• Repeatability - Questions Surrounding Accuracy of ABS Vacuum Forming Process

ConstructionMethod One:Box in a Box

ConstructionMethod Two:Conentional



Both methods of construction proved almost impossible to manufacture accurately examples shown below.

This lead to a complete rethink resulting in a number of actions:

1. The capping and internal must be produced as one continuous element from a single sheet of ABS.

2. To test and perfect the manufacturing process we selected what was considered the most complex element of the design. This was found to be the front section of the offside overhead locker.

3. The team then focused its efforts on finalising the design, producing tooling designs, manufacturing soft tooling, and ultimately manufacture of a locker using a single mould design.

issue 1 - internal skin:

• Rear corners creased and very thin

• Does not fit the surround

• J&A Kay advised issue with mould

• Recessed flange cut off

• Fouls doors

• Capping and internal skin do not sit flush

• gap has not been welded

• “Packers” added to construction

issue 2 - external skin:

• undulations in skin indicate adhesive applied unevenly

• gap should be 3mm

• Actual 15mm

• 1090mm wide at the top

• 1085mm wide at the bottom

• Corners do not follow requested profile

• Skin peeling from upper core


os locker example construction

front capping front view

front capping Rear view



front capping - Test forming

Six test form pieces were produced. Each time the forming method was modified to achieve the desired results.

finished prototype locker section – front view

finished prototype locker section – Rear view


2.3 physical Testing of sub componentsSamples tested:

1. Sandwich panel comprising of 20mm Thermhex core with 6mm ABS face.

2. Sandwich panel comprising of 20mm Thermhex core with 6mm ABS face.

3. 20mm Thermhex panel.

All had Ejot friction welded inserts assembled in accordance with Ejot EPPSys RSD system recommendations.

sample pull-out Test Results

The tests showed a significant increase in the force require to cause yield in samples laminated with a 6mm ABS skin. The load required to cause failure in the sandwich panel was 2.8 times the load required to cause failure in the 20mm Thermhex panel.



sample shear Test Results

The combined results were then used to calculate the number of fixing points in each structural element.

2.4 Doors hinges and latchesFeedback from customers told us transparent doors were preferred to easily identify the contents inside. Three proposals were put forward to the project team for evaluation:

evaluate:

• Proposed EJOT Fixings

• Panel Deflection

• Mathematical Replication

Door DevelopmentExtrusion (Option 1)

Side Mounted Hardened Steel Pinsgas Struts Still Required

Aluminium Extrusions Sprung Loaded Latches


Door DevelopmentComposite Design (Option 2)

Southco Fiction Hinges

Moulded ABS Front Southco Push to Close, AluminiumPush to open Spring Latch Frame

Aluminium PlateBonded to Southco Friction orPolycarbonate Counterweight Hinges

ABS CoversSouthco CatchesRecessed

Door DevelopmentComposite Design (Option 3)



2.5 front bulkhead

using a combination of an aluminium frame and sandwich panel construction produced a structure with equal integrity to our current design. A significant reduction of 29kg or 45%.

6kg Reduction in frame mass (42%)23kg Reduction in cupboard mass (45%)overall Reduction 29kg (45%)

100000

90000

80000

70000

60000

50000

40000

30000

20000

10000

0Current Prototype Pre-Production Production

Frame Mass (g)Design Mass (g)Total Mass (g)


2.6 offside structural layout

33.8kg Reduction in frame mass (70%)21.3kg Reduction in cupboard mass (24%)overall Reduction 55kg (40%)

160000

140000

120000

100000

80000

60000

40000

20000



using a combination of aluminium pressed components and sandwich panel construction produced a structure with equal integrity to our current design. A significant reduction of 55kg or 40%.

2.7 nearside structural elements



using a combination of aluminium pressed components and sandwich panel construction produced a structure with equal integrity to our current design. A less significant reduction of 19.76kg or 19%. The figures are better than the figures suggest when we consider the volume of the rear cupboard has considerably increased over our current design. Bracketry has also been added to house components previously mounted elsewhere on the vehicle.

3. summary & conclusionsAll members of the consortia agreed the work was more challenging than first anticipated. Initial prototype lockers proved a simple sandwich panel type construction method to be the most cost effective. The work also proved the front surround and the internal skin was extremely difficult to assemble. This lead to a significant rethink in the design and manufacturing process. Following a number of meetings between the consortia and tooling manufacturer the solution was found. The solution lay in producing the complex shape part of the lockers and cupboards through the vacuum forming process. Then bond simple shapes to the vacuum formed part to form the finished locker or cupboard. Developing the tooling and a production process to vacuum form the components proved beyond the scope of conventional methods. J & A Kay and their tooling suppliers proved invaluable to the project in developing the tooling and manufacturing processes around the new designs. The whole team feel we have broken new ground in the design and manufacture.

Once the construction method was agreed the O&H design team were tasked with detail design of the other lockers and cupboards within the vehicle interior. This allowed full working models to be created and performance metrics to be evaluated. The project achieved the 100kg weight reduction. The smooth curves achieved through the vacuum forming process realised the modern environment similar to that in modern A & E departments. Dirt and bacteria traps were also eradicated.

3.1 future workFollowing the successful completion of the crash testing and FEA validation, the design will be optimised with a view to further weight reductions.

8.6kg Reduction in frame mass (23%)11kg Reduction in cupboard mass (17%)overall Reduction 19.76kg (19%)

120000

100000

80000

60000

40000

20000




3.2 acknowledgementswww.cenex.co.uk/wp-content/.../RASE-Re-Fuelling-the-Countryside.pdf

ZENKERT, D. - An Introduction to Sandwich Construction Emas Publishing, London (1997)

BITZER, T. - Honeycomb Technology Chapman & Hall, London (1997)

Niche Vehicle NetworkInnovation CentreHolywell ParkAshby RoadLoughboroughLE11 3TU

Tel: 01509 635 750Email: [email protected]

www.nichevehiclenetwork.co.uk

lightweight ambulance report 2015 - … · by working from a clean sheet of paper ... as such felt...

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