Page 68 - Flexible Robotics in Medicine

52 Chapter 3

Figure 3.3
Results for the tensile test of nylon. Only consider the graph of specimen 3 of the nylon wire.

• Acceptance criteria: The force required to bend the endoscope, to 90 degrees, does not
exceed the 31.84 N ( load that weighs 3.25 kg).
• Remarks: The force required to bend the endoscope to 90 degrees does not exceed
31.84 N. However, a nylon string with a higher tensile strength should be used, as the
threshold of 31.84 N might be too low, which may compromise the safety of the subject.

3.4.1.2 Tensile test for polyurethane and TangoBlack-VeroClear composite material

Aim: To determine the mechanical properties of polyurethane and TangoBlack-VeroClear
composite material in order to assess the suitability of TangoBlack-VeroClear as a
substitute material for polyurethane (Fig. 3.4).

Experimental setup:

Experimental procedure:
1. Load the strip of polyurethane onto the Instron machine in the design Med-tech
Realization Studio.
2. Conduct the tensile test.
3. Apply load until the fracture point of the material.
4. Retrieve the data for analysis.
5. Repeat the experiment for TangoBlack-VeroClear composite material.

The TangoBlack-VeroClear composite material is able to withstand a maximum load of
14.59 N (Figs. 3.5 and 3.6). It should be noted that the experiment was terminated when the
polyurethane material is proven to be mechanically stronger than the TangoBlack-
VeroClear composite (polyurethane has not reached the yield point). From the graph