5 Steps Towards Lightweight
Creating lightweight structures seems very straight forward….step by step remove as much material as possible. It’s that simple, right?
I always use 5 steps: understand the product, define the production process, select the material, integration of parts and functionality and finally geometry optimisation. These steps are very intertwined and actually always executed in parallel. I will briefly discuss each of these steps using the lightweight upright as an example.
1. Design Intent
No matter if you start with a clean sheet design or create a lightweight version of an existing product or system, question number one is always: what should it do? What is it’s desired functionality? It’s intent.
Let’s take the motorsport upright as an example. The functionality of the motorsport upright is: transferring the various tire forces from the wheels via the upright, through the suspension arms and into the chassis. On top of that it also has to house a wheel bearing, braking system and various sensors. Key performance parameters are a high camber stiffness combined to a low un-sprung mass.
Benchmarking the original design gives us the suspension joint coordinates, information about the suspension envelope and the available design domain. Lastly, understanding how the parts are used will define the loads acting on the upright in a variety of conditions and situations.
2. Production process
The selection for a manufacturing method is strongly linked with the material selection. In fact in most cases the process and material is selected in parallel, simply because not all materials are available with all manufacturing methods, and vice versa.
For the motorsport upright we have chosen additive manufacturing as the production method of choice. The vision is to offer customer specific products for motorsport and high performance sports cars. For an upright these customisations can be for example a specific brake caliper orientation, or an optimised wheel bearing position. This results in products with a low production volume, often a series of just 1. Limited volume combined with complex lightweight geometries makes additive manufacturing suited for the manufacturing of the uprights.
As mentioned before, the material selection is linked to the manufacturing process and vice versa. Additive manufacturing is still a relative young manufacturing technology, the list of available materials is therefor still limited. Weight reduction and high stiffness are two of the main design drivers for the upright, so specific stiffness is a good starting point in the material selection. Other relevant material selection properties are ease of post processing, fatigue, corrosion resistance and thermal behavior.
Part and function integration reduces the number of joining interfaces. This safes on assembly time and effort, minimises the tolerance stack-up and safes weight associated with fasteners or other joining methods. The original upright consisted of 9 parts, with additional part and functional integration being in the works.
5. Geometry Optimisation
With steps 1 to 4 we have created the framework for geometry optimisation. We have the material properties, know the design rules related to manufacturing, defined the design domain and finally we understand the load cases.
We can define the optimisation targets. For the upright we specified a desired stiffness for the various suspension pick-up points, since this defines the all so important camber stiffness criteria. A generative design or topology optimisation tool can support the engineer in creating the optimal geometry with only material in those places where it contributes in achieving the optimisation targets.
The described steps can be applied to all products, in all industries, using all manufacturing methods and materials. Still need help with this? Contact me at firstname.lastname@example.org
Getting on and off an Adventure motorcycles is a skill on itself. The seat is often high to give good ground clearance and the luggage at the back makes it extra difficult to swing your leg over the seat. Once on it though I have a comfortable seating position with an unobstructed view. With your thighs clamping the bike, your other contact points are Apart from the haptic feedback through the seat, handle bars and foot pegs there it is only a digital on-off passive one-way interaction with the controls.
Riding a motorcycle is riding with all my senses. I can smell, hear and see the nature around me, while sensing the grip beneath the tires. I’m using my whole body to lean the bike through the corners as smooth and perfect as possible. I have never ridden a horse, but I can imagine a comparable feeling. It also requires a certain skill, and it gives a sense of comradery and responsibility. Take care of your horse and the horse will take you where you want to go, albeit way slower than a motorcycle can.
In the open air I’m subjected to the weather, sometimes suffering, often enjoying. Being able to go everywhere, no matter the road condition, gives me an incredible sense of freedom. On the same day you can enter a buzzing city centre, while hours later you are riding a forest trail. It can be intensive though, both physically and mentally, requiring frequent rest stops, where you discover that riding a bike happens to be an excellent conversation starter with the locals.
Why – Current context (2018)
To a baby, adventure is second nature. Everything is new and unusual, you are discovering your environment, testing physical limits while trying out new exiting things. For some of us, this urge remains when grown up, discovering beautiful places, experiencing cultures or meeting new people. Adventure is also a means to get away from everyday structured and organised life, and to experience ultimate freedom.
There are many ways to discover the world, but if you want to cover large distance quickly, you have to fall back to motorised transport. The western world is transitioning towards electrification, although gasoline is still the dominant fuel around the world. The influence of the oil industry is fading with investments being cut back and partially being diverted towards sustainable energy projects.
The transformation toward electric vehicles is mainly driven by incentives and emission regulation, practicality and cost of electric vehicles are still behind the classical combustion engine. State-of-art batteries don’t come near the energy density of gasoline and although hydrogen has a higher energy density, the limited availability, overall system efficiency and cost hold broad adoption of hydrogen fuel cells back.
Centralised mass manufacturing is the common way of making things. Large specialised factories pumping out goods which are distributed around the world. Generalised; Asia exports electronics, Western Europe high tech machinery, while Africa and South America are mining and selling resources. Business wise there is a trend towards vertical integration, meaning; companies possess almost the complete supply chain. Manufacturing, transportation, financing, maintenance and operation by one company. Instead of selling products, we are transforming into a service-based economy. A car as a service, software as a service, even friendship as a service.
The impact of technology is ever increasing. There are high expectations for augmented and virtual reality, although a mainstream use case is still not available. Digital personal assistants, like Amazon Alexa, are getting widespread in the household, taking over more and more simple tasks. It is regarded as the first successful artificial intelligence applications. Meanwhile, Additive Manufacturing or 3D printing, has developed from hype towards a productive industrial tool. For now, especially the aerospace industry is benefiting from the advantages that Additive Manufacturing brings.
In this blog we presented the deconstruction of the adventure motorcycle as we know it today. By analysing the context and interaction, we better understand the current adventure motorcycles. This knowledge helps and inspires us in defining and creating a future context, a future interaction and finally to design the future adventure motorcycle. More about that in the next blog.
I’m the founder and owner of Fransiscó. I have a passion for lightweight and high performance engineering. In this blogs you will find occasionally a write-up of things that keep me busy. I you want to know more about my background, please have a look here…