Plastic Material Degradation and Formation of Microplastic in the Environment: A Review

2021 ◽  
Author(s):  
Shaista Manzoor ◽  
Nafiaah Naqash ◽  
Gowhar Rashid ◽  
Rahul Singh
Keyword(s):  
Plastic Material ◽  
Material Degradation

Analysis of Tension and Bending Response to Characterize Elastic-Plastic Material Behavior

2017 ◽  
Author(s):  
Don Metzger ◽  
Wolf Reinhardt
Keyword(s):  
Plastic Material ◽  
Load Capacity ◽  
Material Behavior ◽  
Material Degradation ◽  
Load Curve ◽  
Bending Mode ◽  
Elastic Plastic Material ◽  
Component Loading ◽  
The Relationship ◽  
Bending Response

The integrity of components can be affected by certain material degradation mechanisms that cause a loss of ductility. In cases where the component loading is primarily in bending, a loss of ductility can significantly reduce the load capacity. Material degradation may be determined by component testing involving the bending mode. In such cases, characterizing the material response in terms of yield stress, ultimate stress and failure strain is complicated by the nature of the load curve due to bending. The objective of this work is to examine in detail the relationship between tensile and bending response, with particular attention to the condition of decreasing ductility.

Masonry: the brittle or plastic material?

2019 ◽  
pp. 22-28
Keyword(s):  
Plastic Material ◽  
Experimental Studies ◽  
Point Of View ◽  
Plastic Properties ◽  
Plastic Deformations ◽  
Base Materials ◽  
Stress States ◽  
Creep Deformations ◽  
Structural Point

The results of experimental studies of masonry on the action of dynamic and static (short-term and long-term) loads are presented. The possibility of plastic deformations in the masonry is analyzed for different types of force effects. The falsity of the proposed approach to the estimation of the coefficient of plasticity of masonry, taking into account the ratio of elastic and total deformations of the masonry is noted. The study of the works of Soviet scientists revealed that the masonry under the action of seismic loads refers to brittle materials in the complete absence of plastic properties in it in the process of instantaneous application of forces. For the cases of uniaxial and plane stress states of the masonry, data on the coefficient of plasticity obtained from the experiment are presented. On the basis of experimental studies the influence of the strength of the so-called base materials (brick, mortar) on the bearing capacity of the masonry, regardless of the nature of the application of forces and the type of its stress state, is noted. The analysis of works of prof. S. V. Polyakov makes it possible to draw a conclusion that at the long application of the load, characteristic for the masonry are not plastic deformations, but creep deformations. It is shown that the proposals of some authors on the need to reduce the level of adhesion of the mortar to the brick for the masonry erected in earthquake-prone regions in order to improve its plastic properties are erroneous both from the structural point of view and from the point of view of ensuring the seismic resistance of structures. It is noted that the proposal to assess the plasticity of the masonry of ceramic brick walls and large-format ceramic stone with a voidness of more than 20% is incorrect, and does not meet the work of the masonry of hollow material. On the basis of the analysis of a large number of research works it is concluded about the fragile work of masonry.

The Issue of Plastic and Microplastic Pollution in Soil

2019 ◽  
Vol 56 (3) ◽  
pp. 484-487 ◽  
Author(s):  
Valentina Constanta Tudor ◽  
Dorina Nicoleta Mocuta ◽  
Ruxandra Florina Teodorescu ◽  
Dragos Ion Smedescu
Keyword(s):  
Water Pollution ◽  
Organic Matter ◽  
Soil Pollution ◽  
Aquatic Environment ◽  
Negative Impact ◽  
Plastic Material ◽  
Soil Biota ◽  
Toxic Substances

Soil pollution with plastics represents a great threat to plants, animals, but especially to humans, as a very small quantity of the plastic which is discarded daily is recycled or incinerated in waste facilities, much of it reaching landfills where their decomposition lasts up to 1000 years and during this time the toxic substances penetrate the soil and the water. If, initially, the pollution with plastics has been identified and recognized in the aquatic environment, recent studies show that plastics residues exist in huge quantities in the soil. The present study focuses on the analysis of factors that pollute soil, so the various studies that have been carried out claim that soil pollution with plastic is much higher and increases in an aggressive manner, being estimated to be 4 to 23 times higher than water pollution with plastics, and the accumulation of microplastics in the soil has a negative impact on soil biota. Thus, once the plastic material accumulates in the soil, it is assimilated to organic matter and the mineral substitutes of the soil and persists for several hundred years.

EXPERIENCE OF RECONSTRUCTION OF THE BREAST WITH THE USE OF THORACODORSAL FLAP

2018 ◽  
Vol 64 (2) ◽  
pp. 206-210
Author(s):  
Petr Krivorotko ◽  
Vladimir Semiglazov ◽  
Aleksey Belyaev ◽  
Kirill Nikolaev ◽  
Tengiz Tabagua ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Plastic Material ◽  
Breast Cancer Patients ◽  
Anterior Axillary Line ◽  
National Medical ◽  
Results Of Treatment ◽  
Implant Placement ◽  
Quality Of Medical Care ◽  
Low Incidence

Purpose: To analyze the results of treatment and the quality of medical care for breast cancer patients with breast reconstruction using thoracodorsal flap (TDF). Material and methods: The study was conducted on the basis of the N.N. Petrov National Medical Research Center of Oncology at the Department of Breast Tumors for the period 2016-2017. When using the reconstruction of the breast with the help of TDF the feature was the complete intersection of the muscle in the anterior-axillary line before closing the defect of the breast tissue but with the preservation of the thoracodorsal vascular sheaf. Surgical treatment was provided to 67 patients with breast cancer including after neoadjuvant therapy. Results: One-time reconstruction was performed in 16 (23.8%) patients under the organ-preserving surgery, mastectomy in two (2.9%) patients and mastectomy with implant placement in 27 (40.2%) patients. Delayed reconstruction of the breast: TDF in combination with the implant - 20 (29.8%), the use of TDF without an implant - 2 (2.9%) patients. Complications were observed in 6 (8.9%) patients. Conclusion: Reconstruction of the breast with TDF is the method of choice and priority for patients who underwent radiation therapy with a lack of integumentary tissues to cover the implant. TDF is a «good» plastic material and could be used in patients with severe defect of breast shape after organ-preserving surgery and mastectomy. TDF is characterized by a low incidence of complications. The use of TDF does not worsen the rehabilitation of patients and does not shift the timing of adjuvant treatment.

scholarly journals Right paraduodenal hernia with extensive bowel gangrene treated with staged surgery: a Bogota bag followed by resection in a low-resource setting

2021 ◽  
Vol 14 (4) ◽  
pp. e239250
Author(s):  
Vijay Anand Ismavel ◽  
Moloti Kichu ◽  
David Paul Hechhula ◽  
Rebecca Yanadi
Keyword(s):  
Plastic Material ◽  
Successful Outcome ◽  
Paraduodenal Hernia ◽  
Transparent Plastic ◽  
Low Resource ◽  
Entire Small Bowel ◽  
Resource Setting ◽  
Low Resource Setting ◽  
Right Paraduodenal Hernia ◽  
Bowel Gangrene

We report a case of right paraduodenal hernia with strangulation of almost the entire small bowel at presentation. Since resection of all bowel of doubtful viability would have resulted in too little residual length to sustain life, a Bogota bag was fashioned using transparent plastic material from an urine drainage bag and the patient monitored intensively for 18 hours. At re-laparotomy, clear demarcation lines had formed with adequate length of viable bowel (100 cm) and resection with anastomosis was done with a good outcome on follow-up, 9 months after surgery. Our description of a rare cause of strangulated intestinal obstruction and a novel method of maximising length of viable bowel is reported for its successful outcome in a low-resource setting.

Fracture Toughness of Large Forgings for Power Producing Industry

2013 ◽  
Vol 577-578 ◽  
pp. 593-596 ◽  
Author(s):  
Václav Mentl
Keyword(s):  
Fracture Toughness ◽  
Chemical Composition ◽  
Steam Turbine ◽  
Mechanical Treatment ◽  
Material Degradation ◽  
The Real ◽  
Operational Safety ◽  
Local Properties ◽  
Thermo Mechanical Treatment ◽  
Shape And Size

The steam turbine rotors represent large components both in radial and axial directions. Their local properties generally differ from one forging to another, or if we compare head and bottom parts of the original ingot, or central and circumferential localities of one rotor body respectively, or if we compare the properties of separate discs e.g. in the case of welded rotors. These differences stem from both even slight changes in the chemical composition (of separate heats or even within one ingot) and thermo-mechanical treatment and in the differences in technology with respect to the real shape and size of the forgings in question. In the paper, the consequences of the differences in fracture toughness characteristics in various rotor localities are discussed with respect to the rotors operational safety taking into account the existence of cracks and material degradation.

scholarly journals Viscoelastic phase-field fracture using the framework of representative crack elements

2021 ◽  
Author(s):  
Bo Yin ◽  
Johannes Storm ◽  
Michael Kaliske
Keyword(s):  
Phase Field ◽  
Consistency Condition ◽  
Field Method ◽  
Anisotropic Elasticity ◽  
Phase Field Method ◽  
Internal Variables ◽  
Crack Model ◽  
Material Degradation ◽  
Discrete Crack ◽  
Deformation State

AbstractThe promising phase-field method has been intensively studied for crack approximation in brittle materials. The realistic representation of material degradation at a fully evolved crack is still one of the main challenges. Several energy split formulations have been postulated to describe the crack evolution physically. A recent approach based on the concept of representative crack elements (RCE) in Storm et al. (The concept of representative crack elements (RCE) for phase-field fracture: anisotropic elasticity and thermo-elasticity. Int J Numer Methods Eng 121:779–805, 2020) introduces a variational framework to derive the kinematically consistent material degradation. The realistic material degradation is further tested using the self-consistency condition, which is particularly compared to a discrete crack model. This work extends the brittle RCE phase-field modeling towards rate-dependent fracture evolution in a viscoelastic continuum. The novelty of this paper is taking internal variables due to viscoelasticity into account to determine the crack deformation state. Meanwhile, a transient extension from Storm et al. (The concept of representative crack elements (RCE) for phase-field fracture: anisotropic elasticity and thermo-elasticity. Int J Numer Methods Eng 121:779–805, 2020) is also considered. The model is derived thermodynamic-consistently and implemented into the FE framework. Several representative numerical examples are investigated, and consequently, the according findings and potential perspectives are discussed to close this paper.

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