Effect of Microstructures on the Shear Strength of Larix kaempferi
Round 1
Reviewer 1 Report
This manuscript is rather descriptive and does not bring about novelty. It is a simple study on shear failure in Larch wood with conclusions that confirm the findings of many earlier studies. It is surprising that the authors recommend in the discussion to choose tree species with small differences in wood density and cell wall thickness between early wood and late wood because here they somehow recommend not to use larch wood. Therefore, it remains unclear what the objectives of this work are. The methodology section mentions equipment where no specific results are shown such as density profilometry or micro CT. Images from light microscopy have very low resolution and the described results cannot be found. Results and discussion are mixed up. The discussion is lacking references to literature.
P1 L16: please describe more clearly what you mean with “brings one to three earlywood cells”
P1 L32: use singular “affect”
P1 L38: what do you mean with “corrosion resistance”? Do you mean natural durability? If so, then please make better reference to studies with biological testing
P2 L58: Here is one of several strange citiation formats in the manuscript using the author´s names: Ulrich is the forename, Müller the surname of the author and this paper is Müller et al.. So please use a better citation format.
P2 L56: correct species name to lower case: Larix sibirica – please correct throughout the manuscript
P2 L64: maybe you mean the “wall-to-lumen ratio”?
P2 L72: “research hotspot” is colloquial English
P2 L80: The same method and conclusion was published about 10 years earlier by Bodner J., M. G. Schlag & G. Grüll (1997): Fracture Initiation and Progress in Wood Specimens Stressed in Tension (Part I&II&III). Holzforschung, 51 & 52
P3 L104: replace “treated with” by “as described in”
Figure 1 capture: add “dimensions in mm”
P3 L 113 replace “sawed” by “sawn”
P3 L115: The equipment Bruker Skyscan seems to be a micro CT but you don´t show such results, please explain this equipment by its principle or exclude this device when it was not used for this study
P3 L117: delete “of the section”
P3 L124f: use plural: “samples” and “Their weight…..”
P3 L127: replace “baked until dry” by “dried until constant mass was achieved”
P4 L133f: The equipment profile density meter may be a X-ray device? Please explain this equipment by its principle but you don´t show results of density profile! Why?
P4 L145: concert Angstrom into SI-unit nm, as you did in chapter 2.5.3
P4 L167f: the samples shown in fig 2 and 3 all have only two rings on the shear plane, how can you explain a minimum of 4 rings?
Table 1 capture: “Correlation coefficient r between…..”
P5 L 195: “morning and evening” are no scientific terms
Figure 3 caption: explain fig a) and b) specifically and in detail
P6 L205f: very unclear description: “….the complete” double (?) “cell wall was not well observed” and “The destruction of the junction……was not completely separated at the growth ring…”
P6 L207: discuss with references in the discussion section
P6 L209f: “…..cells still retained their morphology as visible under a light microscope….”
Figure 4 caption: explain fig a) to d) specifically and in detail; place arrows more precisely on what you want to highlight, this is very unclear; magnification of the images is very low, so that details which are described in the text are not shown
Figure 5: explain clearly why figure a) shows a radial surface and wether it is in earlywood or latewood.
P7 L237: the statemen about crystallinity of mature wood and juvenile wood needs a reference and should be moved to the discussion section.
P8, L242ff: references are missing
P8 L251f: this statement suggests that larch wood is not to choose because as a softwood and larch in particular has large differences in wood density and cell wall thickness between earlywood and latewood.
Conclusions: all these findings have been reported in the literature cited in the reference list, sometimes for other softwood species but with the same principles.
Author Response
Thank you for your comments. Please refer to the attachment for your reply
Author Response File: 
Author Response.doc
Reviewer 2 Report
It is a well-written manuscript with high scientific value. The Authors skillfully combined modern research techniques and the obtained research results with the mechanics of materials and a thorough analysis of the shearing process in one of coniferous wood: Larix kaempferi (Lamb) Carr. I provide my suggestion of minor corrections and changes in the synthetic form.
Introduction
Line 8
The full Latin name of the tested wood should be given at least once in the manuscript.
The full Latin name of the tested wood is Larix kaempferi (Lamb) Carr. The standard English trade name of Larix kaempferi (Lamb) Carr is Japanese larch - according to EN 13556:2003 Round and sawn timber – Nomenclature of timbers used in Europe.
Line 32-33
Editing note:
There should be a break line (space) between “Abstract” and “Keywords”
Materials and methods
Line 99-102
The description of the wood should be completed in my opinion.
How old were the trees?
What part of the trunks was lumber obtained from?
I propose to complete whether it was mature (or juvenile wood), and whether it was heartwood (or sapwood), and whether it was narrow growth ring wood (or wide growth ring wood).
Maybe samples were taken from the entire width of the trunk as recommended by the standard e.g. ISO 4471:1982 Wood. Sampling sample trees and logs for determination of physical and mechanical properties of wood in homogeneous stands. If so, please write it down.
Line 108
Is: …but end of the boards.
It should be: …but end of the samples.
Figure 1
There are an exceptionally large number of methods of wood shear testing which differ in the shape of samples, the way and direction of applying force, and the way of fixing (holding) the samples during testing - they are often placed in special holders. For this reason, it is worth supplementing the drawing (figure 1) with a diagram showing how to hold the sample and apply force during the applied shear test.
For example, such a scheme is in the article:
Qifang Xie, Lipeng Zhang, Zhenglei Yang, Long Wang, Yaopeng Wu, "Behavior of Chinese Dahurian Larch Wood after High-Temperature Exposure: Degradation of Mechanical Properties and Damage Constitutive Model", Advances in Materials Science and Engineering, vol. 2018, Article ID 8614740, 10 pages, 2018. https://doi.org/10.1155/2018/8614740
Results
Line 166
The recorded shear strength is absurdly high. Please check it. It is probably 4.14 MPa (not GPa).
Figure 6
Editing note:
The font size of the markings in the diagrams is too small and therefore unreadable. The font should be enlarged.
Discussion
Line 187-198
When discussing the shear strength, it may be worthwhile to mean that the weakest planes in the wood are the tangential section and radial section too. And when shearing full-size timber members, a stepped miter line usually results.
Line 285-286
Editing note:
There should be a break line (space) between “Conclusions” and “Author Contributions”
Line 292
According to the requirements and publishing template, please give the information about Data Availability Statement (e.g. the data presented in this study are available on request from the corresponding author or something like that).
Author Response
Thank you for your comments. Please refer to the attachment for your reply
Author Response File: Author Response.doc
Round 2
Reviewer 1 Report
The manuscript has improved and it can be recommended for publication after minor revision.
P2, L83f: references 25 and 26 are missing in the text. The strange citation format which is still used in the text lets the readers think that 27 is a reference to a study of Gong. Please make correct citations to a usual format throughout the text.
P5, L172: I still don´t see more than three rings on the share plane of the samples, later you mention that destruction occurred in single growth rings. But there are 4 to 8 growth rings on the whole samples.
P5 L 204: when you name specific samples you should not write rarely but something like: “However, this failure mode only appeared in two out of 40 samples in this study (samples 19 and 38).”
Fig. 4 caption: add detailed description of the images a) to d) in the figures caption
Fig. 5 caption: make more detailed description of what is shown in the figures a) to f) and explain why fig. a) is a radial surface
P9, L 254f: Include references 25 to 27 in this paragraph, they found the same phenomenon 10 years earlier; a more detailed comparison of your findings to literature would be needed in this paragraph; be aware that shear strength is a very important property of timber used in Gulam and CLT.
Author Response
Please see the attachment
Author Response File: Author Response.doc
