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The Murtaya has been designed by leading engineers from the automotive world, ensuring that the latest technology and thinking being employed by the international motoring giants is incorporated into this car. The attention to detail is evident everywhere; from the striking styling, which manages to be menacing yet subtle from every angle; through to the composite monocoque, which provides a fantastic platform for the dynamic performance of the car.
The monocoque and front subframe have been designed using the very latest technology and methods. Cloud modelling of component parts and CAD modelling and analysis ensure that all parts are precision-fit and the chassis is not only perfectly suited for the intended purpose, but designed from the outset to be strong and capable of dealing with the stresses and strains to which it will be exposed in both road and motorsport applications.
The Murtaya features a composite monocoque with GRP clamshell, doors, boot lid, sill extensions and rear bumper. The engine and front suspension bolt onto a spaceframe that is multi pointed to the monocoque in areas specially designed to feed the loads into the structure in a controlled manner, while the rear suspension, propshaft centre bearing and gearbox mount directly to the monocoque.
The result is a very strong platform which allows the suspension to perform its job: keeping the wheels in contact with the road!
The running gear from the iconic Subaru Impreza donor vehicle is used in largely unaltered form, making for a straightforward build. Any necessary modifications (propshaft, gear selector rods and steering knuckle) are carried out by our engineers and included as exchange items in the kits that we offer.
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The use of the rally proven Impreza drivetrain ensures that the performance of the Murtaya is spectacular; not only does the turbocharged engine deliver astonishing straight line pace, but also the incredible levels of traction and cornering grip generated by the four wheel drive give the car simply astonishing ground covering ability, and, all this is backed up by the wonderful offbeat noise, created by the distinctive engine layout.
The exterior styling is the result of an extensive design process considering many factors, including the overall visual impact that the car should create (wow factor!) whilst taking into account practical matters, such as ensuring there is plenty of useable boot space and lots of room for the occupants.
The finished product combines stunning aesthetic appeal with everyday practicality; the Murtaya is a car that can be used for trips to work, the shops, weekends away and annual pilgrimages to Le Mans with no problems (as we did in June 2007) with bags, tents and soft top all happily finding sufficient storage.
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The Murtaya concept is one that has been thoroughly considered, carefully designed and beautifully executed by leading specialists to create an incredible mixture of style and substance, fantastic looks and perception-altering performance.
THE MURTAYA – AN EPIC EXPERIENCE!
Example of local structural analysis
As an illustrative example, this is an analysis report for the rear strut mounting area of the Murtaya. This area is the most heavily loaded point on the monocoque, where suspension loads are reacted directly into the composite structure. This example shows the worst load case for this particular area: a 3g (3 x gravity) bump - this is typical of hitting a large pothole or kerb at speed. The rear bulkhead has been removed from the screenshots to aid clarity.
A 3g bump for the rear corner represents a strut load input of:
3 x 9.81ms-2*(476kg/2 GVW corner weight)=7004N
The layup for the rear strut area of the monocoque is:
- Ply1 600g CSM all over
- Ply2 300g CSM all over
- Ply3: 400g +45deg WR all over
- Ply4: 400g -45deg WR all over
- Ply5: 300g CSM all over
- Ply6: 400g +45deg WR all over
- Ply7: 400g -45deg WR all over
- Ply8: 1000g UD, strut turret side walls layed vertically (0deg)
- Ply9: 300g CSM all over
- Ply10: 400g +45deg WR all over
- Ply11: 400g -45deg WR all over
- Ply12: 300g CSM all over
- Ply13: 400g +45deg WR all over
- Ply14: 400g -45deg WR all over
- Ply15: 600g CSM over strut 'cap'
- Ply16: 600g CSM all over
Screenshots of CAD model prior to FE analysis, with split into zones relating to the ply coverage as above:
Surface with FE mesh and loads/ restraints applied - note greater concentration of nodes/elements at corners and load input points:
Example output of FE analysis - shear stresses in 1st ply:
As can be seen from the above screenshot, the max stresses in this ply are around the strut bolt positions, but still only reach approx 12.8 MPa. The tensile strength of the material in this ply (CSM) is much higher at 86.2Mpa, giving a safety factor of 6.7 (the ratio of Ultimate Stress/Working Stress). A general rule of thumb for composites is that the factor of safety should be a minimum of 2.0 for this particular type of loading, e.g. the maximum working stress can be (86.2/2=43.1Mpa).
The strain levels are checked in a similar way, here showing a maximum 0.2% strain around the bolt holes:
Each of the other 15 plys are analysed in a similar way to ensure stress/ strain levels are well within the working envelope.
The strain energy (not shown here) is also used during the analysis to ensure each part of the structure is ‘working’ equally; this is particularly useful in optimisation of the structural rigidity.
While only a small example, this illustrates how stiffness has been the overriding factor in the design of the Murtaya monocoque. A by-product is that the structure is ‘over-engineered’ in terms of strength.
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