Values for the Mechanical Properties of Wheat, Maize and Wood Pellets for Use in Silo Load Calculations Involving Numerical Methods

Round 1

Reviewer 1 Report

This manuscript is of great interest for the study of mechanical behaviour of granular materials. The experimental tests have been well conducted and are well described, either in the text of the article or in other cited references. The results obtained are very interesting for the scientific field, offering data on mechanical parameters that can be used for the calculation of facilities for transport or storage of these materials, either through traditional formulas or numerical methods. The data obtained on pellets are especially interesting, since it is a material on which very little information is still available. The following clarifications and corrections should be made:

Figure 10: The title of the horizontal axis must be ε_h instead of ε_v

Lines 287 to 294: It should be better explained why a single value of Young's Modulus is chosen and why the one corresponding to a normal stress of 90 kPa is taken. It is not clear neither in the text nor in the mentioned references. The modulus of elasticity depends on the stress state of the material and the maximum value it has reached. We can find, for example, that in a silo the modulus of elasticity is different at different heights.

In the following figures there are texts with a very small font size that will be difficult to see when publishing the article. They should be increased. Figures: Figure7, figure 11 and figure 12.

The scientific name and the variety of the agricultural grains used must be included. In the case of pellets, some characteristics must also be included, such as the type of wood used (species, if it is recycled, etc.), the diameter and length of the pellet, humidity, additives used, if applicable.

Author Response

Please, see the attachment

Author Response File: Author Response.pdf

Reviewer 2 Report

Manuscript ID: agronomy-1715128

The authors present a study on mechanical properties of wheat, maize and wood pellets for use in silo load calculations involving numerical methods. I'm afraid to say that my recommendation is "reject". The reasons for my decision are summarized in the following.

1. Measurement of powder properties is state of the art since several decades. This is done by people working in this field day by day. Thus, I would not say that this article describes "outstanding research" as wished by the Journal.
2. This paper is more like a test report rather than the research paper.
3. The paper adopts different kinds of testers to measure the mechanical properties of wheat, maize and wood pellets. However, a detailed description of the tester (resolution, range, accuracy) is missing.
4. Section 3.1.1, the content and the figure reported is not consistent. It was said “Figure 7 shows the regression line for the Mohr-Coulomb strength envelope obtained for the wheat”, but the regression line formula in figure 7 is for the wood pellets. Further, the regression line formulas presented in lines 174-176 do not supported the results reported in Table 1. The deviation for the apparent cohesion seems very large, over 100%. In this case, what else does it mean?
5. It is not clear how to measure the dilatancy angles
6. I recommend the authors to read the whole manuscript carefully and recheck experimental data before submit the paper.

Author Response

Please, see the attachment

Author Response File: Author Response.pdf

Reviewer 3 Report

Manuscript concerns experimental determination of the basic mechanical properties of granular solids (wheat, maize and wood pellets) important for silo storage design and operations. Experimental procedures are applied correctly. Obtained results provides some new and interesting information important for storage, handling and processing of granular solids. Subject of study is in scope of the journal. I can recommend it for publication after some minor corrections following the particular comments.

Particular comments:

Line 147. „discharge process” – I think Authors mean the unloading process

Fig. 9. “e_v (mm)”. Symbol e is commonly used to express strain, i.e. displacement divided by the initial height. Therfore, I propose to use another symbol for displacement, for example Dh (mm).

Table 6. Due to elastic-plastic behaviour of granulate solids the elastic modulus can be determined only during the unloading process while the loading process allows to determine so called compressibility modulus.

Table 9 v.s. Table 6. E for maize and wood pellets corresponds to values of E from Table 6 for the normal pressure of 128 kPa , while I do not follow how the recommended value of E for wheat was found.

Author Response

Please, see the attachment

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The author answered the propsed questions very well. The paper can be accepated now. Thank you.