User talk:AlexKuprich/sandbox

Article evaluation
An article titled Viscoelasticity was reviewed and evaluated.

The article has a C-Class rating and is a part of WikiProject Physics. The lead section of the article is clear and easy to follow. Article's content relates to its title without any deviation from the topic. Except for a few statements containing somewhat biased (to one's liking) viewpoints, nothing appeared distracting. It is written in neutral tone, although the following statement could be considered as minor bias: "Although the Standard Linear Solid Model is more accurate than the Maxwell and Kelvin–Voigt models in predicting material responses, mathematically it returns inaccurate results for strain under specific loading conditions and is rather difficult to calculate." The final portion of this sentence refers to rather author's viewpoint on complexity of the Standard Linear Solid Model. Another statement that contains somewhat minor bias is as follows: "An expedient way to obtain these coefficients is the following." The author then explains the procedure. While suggested procedure may be an appropriate method for obtaining the coefficients of the Prony series, it is likely to not be the only technique for this purpose.

The article does not particularly lean towards any of its sections. It is rather well-balanced with sufficient coverage of each topic. Article's structure is easy to follow and it contains the necessary headings and subheadings. Adequate amount of images and diagrams in the body of the article makes it easier to understand. Images and diagrams are cited and a reader can see each source by clicking on an image/diagram. Reliable sources are cited throughout the text and the links are functional; however one citation is missing after the following sentence: "Ligaments and tendons are viscoelastic, so the extent of the potential damage to them depends both on the rate of the change of their length as well as on the force applied." The author acknowledges this missing citation. Also, it is assumed that the sources support author's claims based on the titles of those sources. The reason for such an assumption is that most referenced sources do not belong to public domain, and as a result, cannot be readily accessed. Additionally, multiple hyperlinks throughout the article allow the reader to gain more information on the topic matter.

Information in the article appears to be up-to-date while the topic itself represents rather fundamental knowledge that have been studied over a long period of time. Some references date back to 1889, while the others are as recent as 2015.

The Talk page of the article contains feedback and suggestions to the text. The author seems to address those from different editors/contributors. Some editors identified copyright violations and some spotted disagreement between the article and referenced sources. Minor suggestions regarding the formatting of the text were stated as well.

The way this article describes the topic of viscoelasticity can be characterized as an overview. It contains main points of the subject matter as expected from an open encyclopedia article, but does not contain detailed derivations of the main equations. It also differs from an in-class explanation in a way that the material in the article is presented in a condensed manner providing a reader with a concise summary.

Potential Project Topics
1. Consolidation and Deconsolidation in Polymer Composites

Following aspects of the topic are expected to be discussed:

- Consolidation with pressure and deconsolidation without pressure of composite materials

- Complexity of welding of composites

- Effects of deconsolidation on weld quality

2. Effects of Molecular Orientation on Mechanical Properties of Plastic Welds

Following aspects of the topic are expected to be discussed:

- Macro-scale squeeze flow – describing the flow of material at a contact interface and stagnation region

- Strength, toughness and fatigue life of plastic welds

3. Viscoelastic Effects of Polymer Liquids

Following effects are to be discussed:

- The Barus effect

- The Weissenberg effect

- The Kaye effect

Please note that the above mentioned aspects of the potential topics 1 and 2 will be populated, i.e. additional aspects will be added and expanded upon while reviewing the sources. Topic 3 will discuss the fundamentals of the effects listed under that topic. — Preceding unsigned comment added by AlexKuprich (talk • contribs) 22:11, 18 February 2018 (UTC)

Instructor Comments
All three topics are good, but they all seem somewhat advanced. It may be difficult for you to find information for topics 1 and 2. For topic 3, there are already very brief articles on the Weissenberg effect and Kaye effect, but I am not sure that you will be able to expand on those without learning a lot more about viscoelasticity. I think an article just describing the macro squeeze flow during plastic welding with some equations and figures would be sufficient. Please let me know which topic you pick. Thanks! — Preceding unsigned comment added by Benatar.1 (talk • contribs) 22:30, 23 February 2018 (UTC)

Macro squeeze flow during plastic welding
Macro squeeze flow during plastic welding allows to achieve intimate contact at the faying interface between the two parts, which is necessary for creating a sound weld. Gases entrapped between the asperities of mating surfaces may compromise the quality of the weld joint and need to be removed.

Background and theory
During contact hot plate welding, two plastic parts are brought in contact with a hot plate one on each side of the plate. While surface of the hot plate is not perfectly flat, plastic parts retracted away from that surface resemble its shape and therefore contain small asperities.

Two melted parts then come in contact with each other under pressure. Molten plastic layer flows outwards with the flow lines perpendicular to the line of applied pressure. A stagnation point at which no plastic flow occurs, is located at the center of contact area between the two mating parts. Appropriate macro squeeze flow forces the entrapped gases out of the weld region. A flash is then created as a result of the squeeze flow.

With respect to macro squeeze flow, molten layer at the contact interface does not support the force that is applied to the mating parts. The final melt layer thickness for a particular squeeze time can be defined from the following relationship for rectangular parts:


 * $$\frac{h_0}{h_f} = \left(1+\frac{F\cdot t\cdot h_0^2}{2\cdot L^3 \cdot \mu\cdot w}\right)^\frac{1}{2} $$

where
 * h0 – the initial thickness of molten layer of one part
 * hf – the final thickness of molten layer
 * F – applied force
 * t – squeeze time
 * L – thickness of a part
 * μ – viscosity
 * w – width of a part

Similar equation can be written for a circular bar:
 * $$\frac{h_0}{h_f} = \left(1+\frac{16\cdot F\cdot t\cdot h_0^2}{3\cdot \pi\cdot \mu\cdot R^4}\right)^\frac{1}{2} $$

where
 * R – radius of a bar