Consultancy: Durability

"What would you need to do to your product to double its life?"

This question is trickier than it first seems; its the sort of question MIRA's durability engineers have put a lot of thought into solving.  The answer is not to double the strength or thickness of its materials!  The route to finding the answer lies in first understanding what durability means, what factors contribute to it and how durable your product currently is.  To do this you need to know how your product is used.

What is durability?

Durability is the ability of something to perform its function repeatedly.

It is not performance; performance is what a product can do e.g. its speed, acceleration, braking, crash worthiness, strength, rigidity etc.

It is not robustness; robustness is its ability not to break, even if pushed somewhat beyond its expected performance.

Why is durability important?

In vehicle terms, performance is what stimulates customer interest but durability is what sells it.

Cars that will still perform after 3 years of use are the ones with high residual values.

How is your product used?

Do you know what your customers do with your product, where they do it , how hard, how fast, how often and for how long?

Without this information it is likely you are working towards the wrong set of targets!

Converting Product Life Aspirations into Meaningful Durability Targets

When were your durability test schedules established and what are they based on?  If you are unsure or the answer is "we've always done it like this" then you are not alone.  Many manufacturers are testing to old, long established specifications often based on historical best guesses.  Some of these have stood the test of time, so why challenge these specifications? 

• Tests that are too stringent can lead to over engineering and consequently over-weight, more expensive products
• Tests that are not rigorous enough could lead to products that fail in the field leading to warranty claims or worse!

MIRA's durability team offer a full durability engineering service:

• Vehicle target definition
• Usage profiling                                  
• New market correlation
• Global data collection
• Customised schedule
• Load case generation
• Rig drive generation

MIRA's experts in durability can help you to develop durability test schedules which reflect current customer usage and environmental conditions.  Consequently you can expect:

• Improved product quality
• Improved customer satisfaction
• Reduced prototype costs
• Reduced development and warranty costs
• More competitive products

Integrated Durability Engineering (IDE)

Whilst employing dedicated experts in the fields of durability engineering and fatigue analysis, MIRA has pioneered the integration of engineering for durability throughout the product design and development process.  This has meant developing new tools and investing in training but has enabled us to reduce development times but still deliver high quality products.

The overall aim of IDE is to bring together all the relevant engineering disciplines to ensure product designs are optimised for their durability performance, with the advantage that problems are found earlier in the design process, and changes made before investment in expensive tooling.

The key to IDE designing components and systems to last the life of the vehicle.  This necessitates bringing together FEA (Finite Element Analysis) and vehicle dynamics modeling then applying MIRA’s digital proving ground to accurately predict the life of the product.

With IDE, elements of the entire process, from concept through to product realisation and sale are all linked together as inputs and outputs at every stage in the cycle, and are interdependent. From the three areas of vehicle design – strength issues, robustness, and durability – aspects of what is now described as robustness were previously included.

Designing for Durability

For a long time durability has only been considered at the end of a product development programme, usually in the final weeks before it is due to go on sale.  Failures at this stage are very expensive to remedy and can even lead to the whole programme being cancelled.  MIRA has invested in developing methods enabling us to design with durability in mind.  Armed with accurate durability targets and using an integrated approach to durability engineering we are able to remove the uncertainty from the product development programme.

“The resolution achieved is unprecedented in the world of virtual proving grounds“

 Faster development & lower costs

• Confidence that major structural durability issues are resolved early
• All weak areas are identified through the FEA – not just single failure point as found
  in a real rig test
• Alternative designs can be assessed and selected much earlier in the development process
• Design can be optimised before any prototypes exist
• Save time and money by reducing number of prototypes

Virtual Proving Ground

MIRA’s virtual proving ground provides the ability to generate realistic Road Load Data (RLD) using an ADAMS/Car vehicle model. High-resolution virtual representations of the surfaces means that equivalent correlated durability schedules can be conducted without the need for prototype vehicles.

The resolution achieved is unprecedented in the world of virtual proving grounds. The virtual techniques can be combined with physical tests to suit the customers’ requirements and their access to either virtual models or prototype parts.

Virtual Test Rig

MIRA’s virtual test rig is multi-functional and can be driven by either real or virtual proving ground RLD generation. The rig can be used to perform:

• Wheel force transducer data durability analysis (hub-driven – removes the tyre effects)
• Traditional four-poster rig durability analysis (tyre-driven using wheel pads)
• Body fixed or free analysis (to negate or include body-stiffness influences)
  
  By combining virtual rig results with component FEA analysis, virtual durability tests can be performed to generate product life predictions.

Other uses for the Virtual Proving Ground & Test Rig

• Virtual 7-poster rig
• Virtual Kinematics & Compliance rig
• VPG surface profiles driving real 4-poster rig
• Virtual ride modeling 4-poster
• Suspension sensitivity studies – Nibble (wheel out of balance)
  – Shake (eg. powertrain vibration)
  – Judder (disc thickness variation)

Complementary Services and Facilities

Durability consultancy is part of MIRA's comprehensive capabilities for vehicle development and testing.  Further details of which can be found using the following links:

Vehicle Durability

Testing - Environmental Main

Key Life Testing

MIRA - Testing Facilities - Durability and Fatigue
Extensive Proving Ground test circuits

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