scholarly journals Subsequent drawing of anisotropic viscous-plastic material

2021 ◽  
Vol 2021 (5) ◽  
pp. 3-6
Author(s):  
Aleksey Chernyaev ◽  
Dmitry Tesakov
Keyword(s):  
Plastic Material ◽  
Equilibrium Equations ◽  
Linear Condition ◽  
Billet Material ◽  
Stress Computation ◽  
The Impact

The proportions for stress computation at the subsequent drawing of anisotropic billet under conditions of viscoplasticity are obtained. The equilibrium equations in stresses and a linear condition of fluidity are used. The impact of billet bending upon radial areas of a matrix and clamping and also friction is taken into account. The assessment of billet material damageability is carried out.

scholarly journals A method of finding stress solutions for a general plastic material under plane strain and plane stress conditions

2020 ◽  
Vol 37 ◽  
pp. 100-107
Author(s):  
Sergei Alexandrov ◽  
Yeau-Ren Jeng
Keyword(s):  
Coordinate System ◽  
Plane Strain ◽  
Principal Stress ◽  
Plane Stress ◽  
Plastic Material ◽  
Yield Criterion ◽  
Boundary Value ◽  
Equilibrium Equations ◽  
Geometric Problem ◽  
Principal Lines

Abstract A general plastic material under plane strain and plane stress is classified by a yield criterion that depends on both the first and second invariants of the stress tensor. The yield criterion together with the stress equilibrium equations forms a statically determinate system. This system is investigated in the principal lines coordinate system (i.e. the coordinate curves of this coordinate system coincide with trajectories of the principal stress directions). It is shown that the scale factors of the principal lines coordinate system satisfy a simple equation. Using this equation, a method for constructing the principal stress trajectories is developed. Therefore, the boundary value problem of plasticity theory reduces to a purely geometric problem. It is believed that the method developed is useful for solving a wide class of boundary value problems in plasticity.

Mechanical Event Simulation of Drop Testing for Toy Product

2006 ◽  
Vol 532-533 ◽  
pp. 993-996
Author(s):  
Anthony Yee Kai Yam ◽  
Kai Leung Yung ◽  
Chi Wo Lam
Keyword(s):  
Material Properties ◽  
Impact Analysis ◽  
Plastic Material ◽  
Free Fall ◽  
Drop Impact ◽  
Local Analysis ◽  
Element Analysis ◽  
Event Simulation ◽  
Long Time ◽  
The Impact

Toys that are free from drop failures normally take a long time to develop. It is often time and cost consuming after the production tooling is built to detect drop test failure. This paper introduces a new drop testing analysis method for Toys. The method uses a simple approach with a local analysis that based on the linear and non linear finite element analysis. Modeling and transient drop analysis of a pre-school toy is used as a case study to demonstrate the method. The impact analysis of the product hitting the solid concrete floor after a free fall is presented. The analysis focuses on the deformation of the housing for a product with electronic circuit and mechanical mechanism inside. Experimental data has been obtained for drop simulation of the housing and its correlation with the plastic material properties. The stress and strain of the housing during drop impact tests are noted. The effects of the material properties to the housing deflection under drop/impact shock have been investigated. Numerical results are compared with experimental results to validate the method.

scholarly journals The impact of spectra quality on nebular abundances

2020 ◽  
Vol 495 (1) ◽  
pp. 1016-1034 ◽  
Author(s):  
Mónica Rodríguez
Keyword(s):  
Planetary Nebulae ◽  
The Other ◽  
Statistical Equilibrium ◽  
Emission Lines ◽  
Reference Spectrum ◽  
Equilibrium Equations ◽  
Chemical Abundances ◽  
Physical Conditions ◽  
Observational Errors ◽  
The Impact

ABSTRACT I explore the effects of observational errors on nebular chemical abundances using a sample of 179 optical spectra of 42 planetary nebulae (PNe) observed by different authors. The spectra are analysed in a homogeneous way to derive physical conditions and ionic and total abundances. The effects of recombination on the [O ii] and [N ii] emission lines are estimated by including the effective recombination coefficients in the statistical equilibrium equations that are solved for O+ and N+. The results are shown to be significantly different than those derived using previous approaches. The O+ abundances derived with the blue and red lines of [O ii] differ by up to a factor of 6, indicating that the relative intensities of lines widely separated in wavelength can be highly uncertain. In fact, the He ii lines in the range 4000–6800 Å imply that most of the spectra are bluer than expected. Scores are assigned to the spectra using different criteria and the spectrum with the highest score for each PN is taken as the reference spectrum. The differences between the abundances derived with the reference spectrum and those derived with the other spectra available for each object are used to estimate the 1σ observational uncertainties in the final abundances: 0.11 dex for O/H and Ar/H, 0.14 dex for N/H, Ne/H, and Cl/H, and 0.16 dex for S/H.

scholarly journals Characterization of Impacts of Elastic-plastic Spheres

2020 ◽  
Vol 64 (2) ◽  
pp. 165-171
Author(s):  
Bence Szabó ◽  
Attila Kossa
Keyword(s):  
Plastic Material ◽  
Analytical Models ◽  
Material Models ◽  
Elastic Plastic ◽  
Analytical Functions ◽  
Elastic Plastic Material ◽  
Explicit Dynamic ◽  
The Impact ◽  
The Given

This work presents explicit dynamic finite element simulations of various impacts of elastic-plastic solid spheres with flat walls. Different  analytical models describing the mechanics of the impact phenomenon are also presented. Elastic and elastic-plastic material models for the sphere and the wall are considered during the analyses. The applicability of these different models is demonstrated and their accuracies are investigated. Closed-form analytical functions are proposed to describe the relationship between the initial velocity of the sphere and the investigated contact characteristics for the given material models. Analysis is carried out to study the effect of the friction coefficient as well as the angle of impact for various cases.

Degradation of nanoplastics in aquatic environments: reactivity and impact on dissolved organic carbon

2020 ◽  
Author(s):  
Angelica Bianco ◽  
Fabrizio Sordello ◽  
Mikael Ehn ◽  
Davide Vione ◽  
Monica Passananti
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Aqueous Phase ◽  
Surface Waters ◽  
High Resolution Mass Spectrometry ◽  
Degradation Products ◽  
Plastic Material ◽  
Environmental Models ◽  
Reactivity Constant ◽  
The Impact

<p>The large production of plastic material (PlasticsEurope, 2019), together with the mishandling of plastic waste, has resulted in ubiquitous plastic pollution, which now reaches even the most remote areas of the Earth (Allen et al., 2019; Bergmann et al., 2019). Plastics undergo a slow process of erosion in the environment that decreases their size: microplastics (MPs) and nanoplastics (NPs) have diameters between 1 µm and 5 mm and lower than 1 µm, respectively (Frias and Nash, 2019).</p><p>The occurrence, transformation and fate of MPs and NPs in the environment are still unclear. Therefore, the objective of this work is to better understand the reactivity of NPs using an aqueous suspension of polystyrene NPs (PS-NPs) as a proxy, in the presence of sunlight and chemicals oxidants. The results obtained are relevant to both the atmospheric aqueous phase, such as cloud and fog droplets, and surface waters. We investigated the reactivity of PS-NPs with light and with two important oxidants in the environment: ozone (O<sub>3</sub>) and hydroxyl radicals (<sup>•</sup>OH). The adsorption of ozone (O<sub>3</sub>) on PS-NPs is investigated, showing a significant O<sub>3</sub> uptake. Moreover, for the first time, a reactivity constant with <sup>•</sup>OH is determined. We found a linear correlation between the kinetic constants measured for three different sizes of PS-NPs and the surface exposed by the particles. Degradation products (short chain carboxylic acids and aromatic compounds), obtained by direct and <sup>•</sup>OH-mediated photolysis of PS-NPs suspensions, are identified by high-resolution mass spectrometry. Irradiation of a PS-NPs suspension under natural sunlight for 1 year has shown the formation of formic acid and organic compounds similar to those found in riverine and cloud dissolved organic matter.</p><p>This work is crucial to assess the impact of NPs abiotic degradation in atmospheric and surface waters; indeed, the reactivity constant and the degradation products can be implemented in environmental models to estimate the contribution of NPs degradation to the natural dissolved organic matter in the aqueous phase. A preliminary simulation using APEX (Aqueous Photochemistry of Environmentally occurring Xenobiotics) (Bodrato and Vione, 2014) model shows that in NPs-polluted environments (10<sup>9</sup> particles mL<sup>-1</sup>) there is potential for NPs to significantly scavenge <sup>•</sup>OH, if the content of natural organic matter is not too high, as observed for surface and cloud water.</p><p>Allen, S., et al., 2019.  Nat. Geosci. 12, 339–344. https://doi.org/10.1038/s41561-019-0335-5<br>Bergmann, et al., 2019.  Sci. Adv. 5, eaax1157. https://doi.org/10.1126/sciadv.aax1157<br>Bodrato, M., Vione, D., 2014. Environ. Sci.: Processes Impacts 16, 732–740. https://doi.org/10.1039/C3EM00541K<br>Frias, J., Nash, R., 2019. Mar. Pollut. Bull. 138, 145–147. https://doi.org/10.1016/j.marpolbul.2018.11.022</p>

Case Study of Shakedown Evaluation of a Shell With Nozzle Based on Elastic-Plastic Analysis

2017 ◽  
Author(s):  
Jun Shen ◽  
Heng Peng ◽  
Liping Wan ◽  
Yanfang Tang ◽  
Yinghua Liu
Keyword(s):  
Temperature Change ◽  
Plastic Material ◽  
Material Model ◽  
Elastic Plastic ◽  
Perfectly Plastic ◽  
Plastic Analysis ◽  
Elastic Perfectly Plastic ◽  
Temperature Loads ◽  
The Impact

In the past, shakedown evaluation was usually based on the elastic method that the sum of the primary and secondary stress should be limited to 3Sm or the simplified elastic-plastic analysis method. The elastic method is just an approximate analysis, and the rigorous evaluation of shakedown normally requires an elastic-plastic analysis. In this paper, using an elastic perfectly plastic material model, the shakedown analysis was performed by a series of elastic-plastic analyses. Taking a shell with a nozzle subjected to parameterized temperature loads as an example, the impact of temperature change on the shakedown load was discussed and the shakedown loads of this structure at different temperature change rates were also obtained. This study can provide helpful references for engineering design.

The permanent deformation of a cantilever struck transversely at its tip

1955 ◽  
Vol 228 (1175) ◽  
pp. 462-476 ◽  
Keyword(s):  
Plastic Material ◽  
Permanent Deformation ◽  
Rigid Plastic ◽  
Accurate Definition ◽  
Special Cases ◽  
Rigid Plastic Material ◽  
The One ◽  
Definition Of ◽  
Falling Weight ◽  
The Impact

An analysis is given for the deformation of a cantilever made from a rigid-plastic material struck transversely at its tip by a moving mass. Two special cases are found to be of interest: mass of striker large, and mass of striker small. Experiments were carried out on model mildsteel cantilevers under these two extreme conditions: in the one case the striker was a falling weight, in the other a rifle bullet. The theoretical and experimental results are compared, and it is shown that there is good agreement at points remote from the impact, but that prediction of local damage depends on accurate definition of the conditions of striking.

Study on Impinging Stream Flow Channel in Abrasive Flow Polishing Complex Cavity of Precision Mold

2013 ◽  
Vol 797 ◽  
pp. 469-474
Author(s):  
Di Feng Zhou ◽  
Dong Yu Liu
Keyword(s):  
Stream Flow ◽  
Plastic Material ◽  
Material Model ◽  
Impact Deformation ◽  
Element Simulation ◽  
Complex Cavity ◽  
Elastic Plastic Material ◽  
Set Up ◽  
The Impact ◽  
Abrasive Flow Polishing

In order to solve the problem about polishing complex cavity of precision mold, to improve the efficiency of processing and reduce the surface roughness, putting forward multiple entries impinging stream processing device.With making use of the collision of two strands of abrasive flow, Realizing the mutual disturbance of abrasive flow in the runner, and increasing the collision between abrasive to improve the disordering of abrasive movement, for promoting abrasive polishing to mold cavity. Johnson-Cook elastic-plastic material model is set up at the same time, using abaqus finite element simulation to simulate the impact deformation wear and cutting wear with the increasment of impact times.

scholarly journals THE IMPACT OF PHTHALATE ESTERS IN THE ENVIRONMENTAL AND HUMAN HEALTH – ARE THESE COMPOUNDS, A NECESSARY EVIL?

2011 ◽  
Vol 08 (16) ◽  
pp. 52-59
Author(s):  
Marcel Silveira DOS SANTOS
Keyword(s):  
Human Health ◽  
Human Body ◽  
Phthalic Acid ◽  
Plastic Material ◽  
Phthalate Esters ◽  
Alkyl Aryl ◽  
Soil Air ◽  
Benzenedicarboxylic Acid ◽  
Necessary Evil ◽  
The Impact

Phthalates are a group of diesters of phthalic acid (dialkyl or alkyl aryl esters of 1,2-benzenedicarboxylic acid) and they are primarily used as plasticizers (substances added to plastics to increase their flexibility). As the phthalates are not chemically bonded to the polymer, these compounds can migrate from the plastic material to the environment and, consequently, they are found in food, water, soil, air and in the human body. This article discusses the problem of using those compounds, their toxicity and impact on humans and environment. Comments about the four phthalates currently most discussed, measured values and current legislations are presented.

scholarly journals Numerical and Theoretical Analysis of the Inertia Effects and Interfacial Friction in SHPB Test Systems

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4809
Author(s):  
Pei Pei ◽  
Zhongcai Pei ◽  
Zhiyong Tang
Keyword(s):  
Theoretical Analysis ◽  
Elastic Material ◽  
Plastic Material ◽  
Inertia Effects ◽  
Elastic Plastic ◽  
Rate Dependent ◽  
Hardening Modulus ◽  
Structural Applications ◽  
Elastic Plastic Material ◽  
The Impact

The dynamic properties of materials should be analyzed for the material selection and safety design of robots used in the army and other protective structural applications. Split Hopkinson pressure bars (SHPB) is a widely used system for measuring the dynamic behavior of materials between 102 and 104 s−1 strain rates. In order to obtain accurate dynamic parameters of materials, the influences of friction and inertia should be considered in the SHPB tests. In this study, the effects of the friction conditions, specimen shape, and specimen configuration on the SHPB results are numerically investigated for rate-independent material, rate-dependent elastic-plastic material, and rate-dependent visco-elastic material. High-strength steel DP500 and polymethylmethacrylate are the representative materials for the latter two materials. The rate-independent material used the same elastic modulus and hardening modulus as the rate-dependent visco-elastic material but without strain rate effects for comparison. The impact velocities were 3 and 10 m/s. The results show that friction and inertia can produce a significant increase in the flow stress, and their effects are affected by impact velocities. Rate-dependent visco-elasticity material specimen is the most sensitive material to friction and inertia effects among these three materials (rate-independent material, rate-dependent elastic-plastic material, and rate-dependent visco-elastic material). A theoretical analysis based on the conservation of energy is conducted to quantitatively analyze the relationship between the stress measured in the specimen and friction as well as inertia effects. Furthermore, the methods to reduce the influence of friction and inertia effects on the experimental results are further analyzed.

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