Freeform Optimization

7th March 2016

FREEFORM OPTIMIZATION

Freeform optimization (or topology optimization) is a mathematical approach used in finite element analysis to determine the optimum material layout for a given design space which takes into any number of design constraints. By defining a design space that the engineer has to work in and applying boundary conditions such as predefined loads and fixture positions, topology optimization can suggest the ideal layout of material to meet defined performance targets.

Freeform optimisation can be used at the concept level of the design process to arrive at a conceptual design proposal that is then fine tuned for performance, weight and manufacturability. This process replaces time consuming and costly design iterations and hence reduces design development time and overall cost while improving design performance.

It is important to note that design proposals from a freeform optimization study will present an optimal layout of material distribution which may be at odds with the manufacturing processes employed. As such there is still a need for the engineer to interpret the output from the study into a final manufacturable model that can be tested further. However, some new advances in manufacturing techniques such as additive layer manufacturing or 3D printing, has the potential for parts to closer resemble the freeform results.

Another problem is that the solution of a topology optimization problem can be mesh dependent, if no appropriate measure is taken.

This animation of a wing rib shows freeform optimization being used to suggest an ideal material layout given a specified design space and constraints

USE IN INDUSTRY

Freeform optimization is commonly used in industry as a method to reduce the material and overall weight of a component or system as it is capable of giving an engineer guidance on the minimum amount of material required to meet performance characteristics. The applications of the technology within industry are extremely varied but a few examples are presented below.

• Airbus A380 Wing Ribs
Using Altair’s OptiStruct technology, Airbus were able to reduce the weight of the A380’s droop nose wing ribs by 500kg per aircraft. This was achieved by defining the design space available within the wing, applying expected loads, applying freeform optimization and interpreting the result to form a new material layout.

• Tallent Automotive Chassis Development
Tallent Chassis used a combination of freeform and other optimization techniques to develop lightweight chassis structures for their automotive OEM clients. Using their own ‘eDICT’ system, Tallent Automotive successfully reduced the mass of various chassis components by as much as 25%.

• Shanghai Automotive Vehicle Development
By integrating optimization techniques into the vehicle development process at Shanghai Automotive (SAIC), it was possible to create a performance optimized design for the Roewe 550 in an aggressive timescale.

SIMULATION DRIVEN DESIGN

As the power and sophistication of simulation technology has improved, it has opened up the potential for design optimization to be applied earlier in the development process. This has created a new process for product development which Altair refer to as ‘Simulation Driven Design’.

What is it?
In the traditional design process, computer aided design (CAD) and computer aided engineering (CAE) tools are used sequentially. The designer creates the geometry in CAD and verifies it using CAE.

With the simulation driven design approach, CAD and CAE are deployed in parallel. CAE, using intelligent technology, automatically determines the optimum geometric configuration, allowing engineers to reach the best performing design, faster.

Benefits
The simulation driven design approach utilizes freeform and other optimization methods to generate more mature design solutions much earlier than in a traditional development process. This allows engineers to create products which are optimized for mass and weight targets at a stage when the cost of change is at its lowest and the potential impact at its highest.

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