FlexFlax Stool: Validation of Moldless Fabrication of Complex Spatial Forms of Natural Fiber-Reinforced Polymer (NFRP) Structures through an Integrative Approach of Tailored Fiber Placement and Coreless Filament Winding Techniques
and Hanaa Dahy 2,3Round 1
Reviewer 1 Report
The paper deals with the design and the manifacturing of a lightweight FlexFlax Chair.
Since I'm a structural engineer, I will focus only on section 3.4, which sounds to me to be the least exhaustive. There is nothing in this work to verify the actual carrying capacity of the chair; at least one experimental force -displacement curve, in elastic field, i.e. for low load values, should be produced in order to understand if the ability to sustain up to 100kg should be verified! No information on the constitutive law of the 2400 Tex roving, neither of the impregnated fibres, are provided. Also a simple FEM model in order to understand the effective stress state is missing!
Moreover the conclusion are missing
I am sincere: the world of lightweight FlexFlax Stool structures is really fascinating and lightweight FlexFlax Stool structures could be the future in the architecture. However, even if I understand that the manufactured object is a prototype, there are several improvements to carry out before publish this work.
Author Response
Please see the attachment
Author Response File: 
Author Response.docx
Reviewer 2 Report
This is an interesting interdisciplinary paper about the integration of two emergent fabrication techniques, namely Tailored Fibre Placement (TFP) and Coreless Filament Winding (CFW), which are deployed with Natural Fibre-Reinforced Polymers (NFRP).
There are several major and minor questions that should be clarified.
The design methodology has some gaps, which must be corrected, e.g. the validation of the initial hypothesis is not sufficiently described.
Analysis criteria:
It should be 2. Minimalization of the total weight of stool and corresponding material usage.
The point “3. Qualitative comfort enabled by the geometry”. – Is not described in the results section 3.3.2 Seating test
3.1 Topological Optimization:
The assumptions of the Topology Optimization in SolidWorks should be described.
For example - the material properties
In the protype, Natural Fibre-Reinforced Polymers with anisotropic properties were used.
In the example (Fig. 8) it looks like one layer of solid material with isotropic properties was used.
This SolidWorks model is very simplified and therefore “this simulation did not provide the definitive visual pattern of the surface, but rather guided the TFP surface design.”
Currently, the SolidWorks Topology Optimization includes 3 goals:
- Best Stiffness to Weight Ratio,
- Minimal mass,
- Minimize the maximum displacement.
Which one was used in this case?
3.2.1
Due to the anisotropic nature of fibrous composites, “the above-mentioned optimization process was combined with an interpretation of Classical Lamination Theory (CLT) [16,17] (Figure 9), which enabled the flexible behaviour of the bending zones.”
The bending process and assembly of the all layers should be described more precisely.
What are the external dimensions of the stool?
I guess that the destructive compression test will be included in the next article.
Minor comments:
Abstract:
It should be clarified, that:
"This culminates in a lightweight FlexFlax Stool design (ca. 1kg) which can carry approximately 100 80 times its weight."
(Maybe it can carry more, but that should be tested.)
I suggest the inclusion of one additional keyword: "rapid prototyping".
Fig.3 All subpictures looks the same
References should be cited in the order of appearance.
The reference [13] should be placed closer to cited text.
The reference [20] is not cited in the text.
The reference section should be correctly formatted.
Author Response
Please see the attachment
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
The reviewer thanks the author for the effort made to meet the requests
Reviewer 2 Report
The authors have sufficiently improved the description of the research methodology.
There is only a small typographic error in “5300N” on the page 16, and the references 5 and 20 are cited in the wrong order.
