Composite foot is designed to fix artifitial leg without an ankle device. The male pyramid adapter is fixed to the composite body by three bolts.

 
Figure 1.  AKTIV Foot

Carbon heel stores energy and absorbs impact forces. 

The lay-up of carbon fiber foot ensures that the deflections of forefoot and heel are proportional to the user's weight and activity level, and achieve maximum efficiency.


Figure 2. AKTIV Foot

The split toe offers inversion/eversion for stability on uneven terrain.

Some computer based design and analysis programs were used in design of the composite prosthetic foot. These programs make it easier to reach effective models and more accurate engineering analysis.

As seen in Figure 2 , the cross-sectional thickness is not constant along the body. So the body is devided into several areas in the finite element analysis, to define layer numbers and orientation angles of carbon fibres. Layered elements are shown in Figure 4.


Figure 3. Divided model

In the mechanical analysis of the prosthetic foot, ISO 10328 Testing prosedure is selected as referance. The testing forces are applied in FEM analysis and mechanical testing, both, as shown in Figure 5.


Figure 4. Position of the foot in test equipment





Table 1.  Angles of directions of loading.
 



You can see displacement that occurs against the load on keel of the feet in Figure 6. This dispacement test has been achieved by using ankle-foot testing device according to ISO 10328.

Figure 5.  Displacement on heel and toe

The results of a study from literature was used in our design. Some famous brand foot models were tested as samples in that study.

 Graphic in Figure 7, belongs to AKTIV Foot and the other graphic in Figure 8, belongs to a different carbon foot of another famous brand.
You can see some pictures that show FEM results, below.