Proceedings in Manufacturing Systems

Journal

PROCEEDINGS IN MANUFACTURING SYSTEMS

PAPER REVIEW FORM

Title: FEM APPLICATION FOR ANALYSIS OF THE OPTIMAL STRUCTURE VARIANTS FOR HOT BILLETS AUTOMATIC-LOADING SYSTEM

Author(s): Georgi GEORGIEV

Reviewed by:Prof. dr. ing. Stefan Dan Pastrama.

Institution:University Politehnica of Bucharest, Faculty Engineering and Management of Technological Systems, Department of Strength of Materials

Date: 23.05.2010Signature: ……………………………

Comments of the reviewer

The paper presents a finite element analysis for an automatic loading system for production of aluminum profiles. Three variant for this device, obtained following an optimization procedure, are considered.

The paper COULD BE interesting since the analyzed structure is complex and it is difficult to obtain a reliable model for a finite element analysis in such case. Nevertheless, the content of the paper must be considerably changed in order to make it suitable for publication in a prestigious journal. The following suggestions of the reviewer must be taken into account by the author:

- The introduction does not explain the most important thing: what is the structure to be analyzed? At the beginning, very few words are written about the device. No picture is shown, nothing about the functional role, nothing about the dimensions, or about what parts are components of this device.

- The author states that there may be 637 variants of this device, but he does not explain how did he chose these variants, what is the difference between them, what are the elementary executer devices, what are the functions that they execute and what are the relations between them. Indeed, some references are pointed here, but they are not easily available to the reader and, more than that, one of the references is in Bulgarian, so for non-Bulgarian people, it is useless.

- The three variants considered for the paper were selected based on ”solutions of two monocriteria and one multicriteria optimization problems”. These criteria are not explained. Only two criteria are named (minimalprice and minimal technological cost price). If the author does not explain what are the parameters that form these prices, it may seem that they are the same criterion. Muticriteria means several criteria but here we have only one (or two, if the author explains the difference between these two prices).

- The parameters chosen for optimization (weight, volume, cost, time of manufacturing, or other considered in this case) should be clearly explained in order to make the reader to understand how these variants were chosen. Instead, the author denotes these parameters as X13, X21, etc. Nobody understands what means such notations.

- The purpose of the finite element analyses is not explained. At the end, the author states that “selected variants are able to perform its functions in flow line for production of aluminum profiles”. How did he come to this conclusion? Only the values of maximum stress and displacement are listed as results. Are these values smaller than an imposed limit? If yes, how was this limit established?

- An entire page is devoted to the equations of different types of analysis (static, dynamic, buckling, heat transfer, etc) in the finite element method. These equations were probably introduced in order to fit the number of pages required by the journal, but they are useless, since, as one can observe, only static analysis is performed. In this case, there is no need to explain how a transient analysis is made. This part (except the equations for static analysis – paragraph 2.1) should be completely removed from the paper. Instead, the author may describe how the model was achieved in CATIA, with pictures and explanation about the assembly of the different part of the device.

- The type of element is not specified (brick, shell, etc.)

- Instead of introducing tables for loads, it would be more suggestive and clear for the reader to show a picture of the finite element model with loads shown as arrows, with values. In tables, values for the load on the OY and Oz axis are listed, but nobody understands where is this load applied? Also, no constraints are listed in tables. This means the device is moving? If so, the analysis should be dynamic not static.

- It is useless to list a minimum value of the stress of 4.9645e-013 MPa. This is cleary ZERO, it is well known that the finite element method is approximate. The same for displacements.

-It is not clear what means a ramped load, more explanations should be given. Also, it should be stated how were the values of the loads chosen?

- At the end – in the paragraph “Conclusions”, the author states that “ the load is 1.5 times over of the maximal load” (in English, correct is MAXIMUM not maximal). At paragraph 3 “Results” it is written that “The maximal payload of each arm is 200 N”. This means the force should be 1.5 x 200 = 300N. But in the tables where loads are listed, a value of 100N is considered for variants 1 and 3, and less than this for variant 2. The author should explain this difference.

- The English grammar and spelling is sometimes impossible to understand. The author should consult a person that knows English very well, since many parts of the paper are totally unclear due to the language faults.

CONCLUSION: the paper may be published after considerable changes and revisions, following the above mentioned comments.

The referee will re-review the paper when the suggested changes are made.