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Design and AM of a medical face shield
Table 5. Final product specifications for a face mask.

Functions Requirements Metric Units Limit values Ideal values
F1 Elasticity Tensile strength at yield MPa >35.9 34
Ease of usage Ergonomic design Yes/ No Yes Yes
F2 Respect DfAM AM technologies - MEX, SLA, SLS MEX
principles
F3 Comfortable Wear period hours >6 8
Maintains position Ensures user protection Yes/No Yes Yes
Prevents condensation Ensures ventilation Yes/No Yes Yes
features
F4 Single frame design Number of components No. 3 2
Allow reuse Sterilization procedure - Autoclave, UV, Disinfectant
disinfectant liquids, ozone liquids, ozone
F5 Ease of maintenance Maintenance manual Yes/No Yes Yes
Ease of assembly Assembly/disassembly minutes 0.5 0.5
time
F6 Biodegradable filaments Thermoplastics - PLA PLA
Environmental friendly Recyclable Yes/No Yes Yes
F7 Light weight Total weight g <20 10
F8 AM produced Total production time minutes <60 45
(3D printing+post
processing+assembly)
F9 AM produced Production rate products/day/ <10 8
machine
F10 AM/plastic injection Modular/parametric Yes/No Yes/No Yes
design

skewness metric, which is one of the primary mesh which are lower than the material tensile stress
quality measures in a FEA, was checked. The shape at yield (which is 110 MPa). These numerical
and asymmetry of distribution can be measured by and visual results obtained from the simulation
its skewness, which can be considered as the mesh indicated that the stress distribution on the
quality verification of a FEM . The skewness product is uniform and the elastic deformation
[22]
value of zero indicates an equilateral cell (best) and ability of the product is satisfactorily within
a value of one indicates a completely degenerate cell the design limits. For the second scenario, the
(worst) . At the final meshing operation, FEM was head holding force after wearing was calculated
[23]
created with minimum element size of 0.4 mm, and as 2.744 N against each side displacements.
the average skewness value of 0.227 was obtained. This finding was also interpreted as the head
This value indicated that the FE model used in the holding capability of the product and was in a
loading scenarios has an excellent mesh quality. satisfactory comfort range.
Details related to the FEA set up, and simulation 2.8 Physical prototyping
outputs are given in Figure 5.
The results of the FEA scenarios revealed that As a dimensionally accurate physical part, the AM
there was no plastic deformation (permanent prototype is able to give the designer a sense of the
deformation) during the maximum opening appropriateness of form and fit before continuing
condition of wearing on the head and at the with production . The fastest technique to
[24]
head holding positions. Maximum equivalent produce a physical prototype, most especially for
(Von-Mises) stress during the maximum opening a complex geometric structure, is utilizing AM
condition and at the head holding position were technology. In short, models were created by adding
96.498 MPa and 58.929 MPa, respectively, successive layers of material together. To evaluate

42 International Journal of Bioprinting (2020)–Volume 6, Issue 4