case | ankle foot orthosis

“Innovation walks ahead”

THE CHALLENGE

Our goal was to find the right design and to select a suitable material, combined with ensuring optimal producibility and a short product development time.

For selecting the right material and to develop a proper design, we had to take in mind the following: To be able to walk unhindered, the user should not encounter difficulty by the AFO frame, so this asks for much flexibility. Also, when the foot is lifted during the swing phase of walking, the AFO should be stiff enough to provide sufficient support to the foot.

In summary, the aim was to find the right balance between flexibility in one direction and stiffness in the other direction.


OUR SOLUTION

In the process of optimising the Ankle Foot Orthosis, we have taken multiple steps. To be able to efficiently alter the design, we have employed Finite Element Analyses to create a virtual model of the AFO. Defining realistic load cases was key, since the loads exerted onto the AFO are different each time because each AFO user is unique. To define realistic load cases, we have collaborated with Nea International B.V. and with a physiotherapist.

The AFO design was optimised with respect to stiffness and flexibility for the defined load cases. By identifying the critical locations with respect to strength, the design of the AFO could be improved. This led to a robust design that prevents tearing of the material while being used.

Our virtual development approach shortened the development time, reduced the number of expensive prototypes and resulted in a robust and lightweight design.
WHAT WE DID

FINITE ELEMENT MODEL VALIDATION

Based on the initial AFO design, an FE-model was created. Using tensile test results of the proposed material, we have derived a representative material model. Using test results from physical prototypes, the FE-model has been validated. This model became the basis for the optimisation of the AFO design. This CAE-driven engineering approach shortens the duration of the design process and reduces the number of expensive prototypes.

LOAD CASE DEFINITION

The loading conditions of the AFO during operation play a decisive role in the design. Therefore, additional attention was paid to defining several representative load cases, which have been used for the design optimisation.

Every user of an AFO uses the aid under different circumstances. Together with a physiotherapist and with Nea International’s design engineers, we have investigated the way an AFO is used on a daily basis.


MATERIAL SELECTION

Based on the FE-simulation results, the preferred material behaviour was defined. By comparing several proposed materials, the best performing material was selected with respect to stiffness, elastic behaviour and strength.

PRODUCIBILITY ANALYSIS

Cooperation in the value chain is key. In this case we teamed up with Nea International's injection moulding partner, who is specialised in producing high performance sports and medical applications. Combining expertise creates an even greater traction and shortens time to market.

Using injection moulding simulations, the producibility of the new design was evaluated. With this analysis, we have identified attention points in the production process, such as air traps and weld lines. The intensive collaboration with the injection moulder resulted in a design with guaranteed manufacturability.



OUR RESULTS

  • Optimal robust design with the right balance between stiffness and flexibility
     
  • Lowest possible weight for maximum comfort
     
  • Short time to market, enabled by CAE-driven development approach
     
  • Guaranteed producibility

INQUIRIES?

Interested to learn more about our way of working?

CONTACT PAUL HABETS

Are you developing a new product? Or do you wish to have your current design validated or optimised? Please give us a call. We look forward to talk with you.

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