scholarly journals The Influence of the Characteristics of Plastic Materials Used in the Performance of the Thoraco-Lumbar Orthoses

2018 ◽  
Vol 55 (1) ◽  
pp. 85-90 ◽  
Author(s):  
Constantin Nanu ◽  
Ion Poeata ◽  
Cezar Popescu ◽  
Lucian Eva ◽  
Bogdan Florin Toma ◽  
...  
Keyword(s):  
Plastic Material ◽  
Burst Fracture ◽  
Rigid Plastic ◽  
Element Analysis ◽  
Plastic Materials ◽  
Plastic Type ◽  
Lumbar Area ◽  
Bone Fragments ◽  
Materials Used ◽  
State Of Tension

The aim of the paper is to identify the of optimal plastic type used in obtaining thoraco-lumbar orthoses - used in the treatments of comminutive fracture, of burst fracture type of the vertebrae in the lumbar area. For this purpose, with the help of Finite Element Analysis (FEA), a theoretical study was carried out on the influence of elastic properties of plastics, used in the achieving of lumbar orthoses, on the state of tension and on the local displacements of the bone fragments from the traumatized area under the condition of the movement from the base of extension and flexion. In the study the force of flexion, the force of extension and the elastic modulus of plastic material varied on three levels. The theoretical results obtained were completed with clinical trials carried out on a total of 26 patients who suffer thoraco-lumbar comminutive fracture, burst fractures type, at vertebra T11 and were immobilized in Boston-type plastic orthoses made of: polypropylene (PP), rigid vinyl polychloride (PVC-D) and polytetrafluoroethylene (PTFE). As a result of observations, it was found that the use of an orthesis made from rigid plastic material, although it appears higher stresses in the traumatized zone, the displacements of bone fragments are smaller, the pains is higher in the fractured zone, the angle of kyphosis (LKA) close to the normal value and a better mobility of the spine (ODI indicator).

Places and Causes of Mismanaged Plastic Materials in the Life Cycle of Flexible Plastic Packaging Based on Mechanical Recycling Context

2021 ◽  
Vol 888 ◽  
pp. 129-138
Author(s):  
Munzir Hadengganan ◽  
Djoko Sihono Gabriel
Keyword(s):  
Life Cycle ◽  
Plastic Material ◽  
Life Cycles ◽  
Plastic Waste ◽  
Production Cycle ◽  
Mechanical Recycling ◽  
Rigid Plastic ◽  
Plastic Packaging ◽  
Quality Degradation ◽  
Plastic Materials

Plastic waste has become a big issue in the world for its large amount of plastic waste in the sea. Most of the plastic waste is plastic packaging which consists of flexible and rigid plastic packaging. This research discusses flexible plastic packaging. Until now, most researches on the loss of plastic materials discuss how to manage plastic waste disposal once it has been used by community: only a few discuss production cycle: while none of them discusses flexible plastic packaging area. This research aims to examine the number of mismanaged materials throughout flexible plastic packaging life cycle using a combination of Material Flow Analysis (MFA) and Life Cycle Analysis (LCA). Based on the literature review, interviews and observations conducted by the author to all stakeholders in the life cycle of flexible plastic packaging, mismanagement of plastic material occurred in each cycle, mostly caused by quality degradation of flexible plastic that could cause plastic waste was not acceptable in the mechanical recycle. The results of this study show that: (1) mismanaged material occurred in all cycles throughout the life cycles of flexible plastic packaging, (2) quality degradation is the main caused of mismanaged material in several cycles, and (3) the mismanaged materials in the life cycle of flexible plastic packaging were 98.29%.

AXIAL CRUSHING OF TRIANGULAR TUBES

2013 ◽  
Vol 05 (01) ◽  
pp. 1350008 ◽  
Author(s):  
Z. FAN ◽  
G. LU ◽  
T. X. YU ◽  
K. LIU
Keyword(s):  
Plastic Material ◽  
Progressive Collapse ◽  
Material Model ◽  
Acute Angle ◽  
Rigid Plastic ◽  
Element Analysis ◽  
Axial Crushing ◽  
Rigid Plastic Material ◽  
Theoretical Predictions ◽  
New Type

In the present paper, the mechanical behavior of large deformation of a regular equilateral triangular tube under quasi-static axial crushing is reported, which is a polygon with an acute angle and odd number of sides. Based on the results from nonlinear finite element analysis (FEA), a new type of inextensional basic plastic collapse folding element is proposed to describe the plastic progressive collapse. The progressive folding around the stationary horizontal hinges and inclined traveling hinges are involved to develop the new basic folding element. Two types of inextensible deformation modes are discovered, i.e., diamond mode and rotational symmetrical mode. The average crushing load for each mode is predicted from the super-folding element theory, which was proposed from the previous investigation on the axial crushing of square columns. A rigid-plastic material model and a kinematically admissible model are involved in this theory. The results are further validated against experiments. The approximate quasi-static theoretical predictions for the mean crushing loads of triangular tubes provide reasonable agreement with the corresponding experimental results.

scholarly journals A Simplified Analysis of the Post-buckling Behavior of a Compressed Reinforcing Bar

10.14311/650 ◽  
2004 ◽  
Vol 44 (5-6) ◽  
Author(s):  
P. Kabele
Keyword(s):  
Plastic Material ◽  
Axial Loading ◽  
Central Line ◽  
Material Behavior ◽  
Multiscale Approach ◽  
Rigid Plastic ◽  
Element Analysis ◽  
Reinforcing Bar ◽  
Buckling Behavior ◽  
Post Buckling

Recently, a computational methodology based on a sequential multiscale approach, which facilitates numerical simulation of an R/C building demolition has been developed. In this type of analysis, it is necessary to capture the behavior of compressed reinforcement bars until complete rupture, which occurs due to extensive bending in the post-buckling regime. To this end, a simplified analytical model of the post-buckling behavior of a compressed bar is proposed. The simplification consists namely in considering rigid-plastic material behavior, neglecting axial contraction of the central line, and approximating the shape of the deformed central line in the plastic hinges by a circular arch. Consequently, the axial loading force, bar end displacement, and extreme strain can be expressed in relatively simple closed forms. The results obtained with the proposed model show very close agreement with those obtained by a detailed and realistic finite element analysis, which justifies the use of the simplifying assumptions. 

scholarly journals Comparative Study on the Effect of Three Disinfection Procedure on the Streptococcus pyogenes Biofilm Formed on Plastic Materials Used in Paedodontics and Orthodontics

2017 ◽  
Vol 54 (1) ◽  
pp. 116-118
Author(s):  
Alexandru Simion Ogodescu ◽  
Alexandru Attila Morvay ◽  
Adriana Balan ◽  
Laura Gavrila ◽  
Ana Petcu ◽  
...  
Keyword(s):  
Streptococcus Pyogenes ◽  
Laser Scanning ◽  
Plastic Material ◽  
Plastic Substrate ◽  
Confocal Laser ◽  
Photodynamic Effect ◽  
Plastic Materials ◽  
Disinfection Procedure ◽  
Oral Microbiology ◽  
Materials Used

Plastic materials are widely used today in Paedodontics and Orthodontics for manufacturing preventive and therapeutic devices. Since these are worn for long times in the oral cavity biofilm forms on the smooth acrylic surfaces of those appliances. The biofilm must be removed not to destroy the oral microbiology. The aim of this study was to research the possibility of removing the microbial biofilm and disinfecting retainers using the photodynamic effect of toluidine blue O, Fotosan System (CMS Dental, Copenhagen, Denmark) in comparison to two products available on the market Corega Denture Cleanser Tablets (GlaxoSmithKline) and the Retainer Brite� Cleaning Tablets (DENTSPLY International Raintree Essix, FL, USA). The plastic material used in this experiment was the cold-cure acrylic Palapress� vario (Heraeus-Kulzer GmbH, Hanau, Germany). Images of the biofilm formed by Streptococcus pyogenes were obtained using a confocal laser scanning m icroscope. The images were analyzed using Comstat 2 software. The results showed that all the three investigated methods had a disinfectant effect. Corega Denture Cleanser Tablets reduced most of the biofilm formed on the plastic substrate.

The Theoretical Analysis of Metal-Forming Problems in Plane Strain

1952 ◽  
Vol 19 (1) ◽  
pp. 97-103
Author(s):  
E. H. Lee
Keyword(s):  
Plane Strain ◽  
Metal Forming ◽  
Plastic Material ◽  
Large Strains ◽  
Rigid Plastic ◽  
Small Strains ◽  
Plastic Type ◽  
Static Determinacy ◽  
Complete Solutions

Abstract The plastic flow in plane strain of an ideally plastic material subjected to large strains is considered. Elastic strains are negligible and a rigid-plastic type of analysis is adopted. The equations to be satisfied are detailed, and they include stress and velocity equations in the plastic regions, as well as consideration of the stress field in the rigid regions to check the validity of small strains there. Complete solutions satisfying these conditions require the determination of the rigid-plastic boundaries to delineate the regions in which the various conditions must be satisfied. The fallacy of static determinacy of such problems in terms of the stress equations only is emphasized. The study of complete solutions indicates errors in solutions commonly accepted in the literature which are based on the stress equations only. Examples are discussed. The general occurrence of velocities in the boundary conditions of forming problems is pointed out, and the difficulty of setting such problems in terms of boundary stresses only is illustrated by examples.

scholarly journals Study of the Biodegrability of Degradable/Biodegradable Plastic Material in a Controlled Composting Environment

2012 ◽  
Vol 19 (3) ◽  
pp. 347-358 ◽  
Author(s):  
Magdalena Vaverková ◽  
František Toman ◽  
Dana Adamcová ◽  
Jana Kotovicová
Keyword(s):  
Plastic Material ◽  
Laboratory Scale ◽  
Biodegradable Plastic ◽  
Preliminary Evaluation ◽  
The Czech Republic ◽  
Chain Stores ◽  
Plastic Bags ◽  
Plastic Materials ◽  
Scale Test

Study of the Biodegrability of Degradable/Biodegradable Plastic Material in a Controlled Composting EnvironmentThe objective of this study was to determine the degrability/biodegradability of disposable plastic bags available on the market that are labeled as degradable/biodegradable and those certified as compost. The investigated materials were obtained from chain stores in the Czech Republic and Poland. Seven kinds of bags (commercially available) were used in this study. One of them was a disposable bag made of HDPE and mixed with totally degradable plastic additive (TDPA additive). Another was a disposable made of polyethylene with the addition of pro-oxidant additive (d2w additive). One was labeled as 100% degradable within various periods of time, from three months up to three years, and four were certified as compostable. The test was carried out in a controlled composting environment. The biodisintegration degree of the obtained pieces was evaluated following a modified version of ČSN EN 14806 Norm "Packaging - Preliminary evaluation of the disintegration of the packaging materials under simulated composting conditions in a laboratory scale test" and a modified version of ČSN EN ISO 20200 "Plastics - Determination of the degree of disintegration of plastic materials under simulated composting conditions in laboratory-scale test" (ISO 20200:2004). The emphasis was put on determination whether the bags are degradable/biodegradable or not.

Elasto-Plastic Coupled Temperature-Displacement Finite Element Analysis of Two-Dimensional Rolling-Sliding Contact With a Translating Heat Source

1991 ◽  
Vol 113 (1) ◽  
pp. 93-101 ◽  
Author(s):  
S. M. Kulkarni ◽  
C. A. Rubin ◽  
G. T. Hahn
Keyword(s):  
Finite Element ◽  
Half Space ◽  
Plastic Material ◽  
Element Model ◽  
Rolling Contact ◽  
Two Dimensional ◽  
Element Analysis ◽  
Element Mesh ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic

The present paper, describes a transient translating elasto-plastic thermo-mechanical finite element model to study 2-D frictional rolling contact. Frictional two-dimensional contact is simulated by repeatedly translating a non-uniform thermo-mechanical distribution across the surface of an elasto-plastic half space. The half space is represented by a two dimensional finite element mesh with appropriate boundaries. Calculations are for an elastic-perfectly plastic material and the selected thermo-physical properties are assumed to be temperature independent. The paper presents temperature variations, stress and plastic strain distributions and deformations. Residual tensile stresses are observed. The magnitude and depth of these stresses depends on 1) the temperature gradients and 2) the magnitudes of the normal and tangential tractions.

On Determining Elastic Modulus from Instrumented Indentation

2013 ◽  
Vol 668 ◽  
pp. 616-620
Author(s):  
Shuai Huang ◽  
Huang Yuan
Keyword(s):  
Finite Element ◽  
Elastic Modulus ◽  
Plastic Material ◽  
Instrumented Indentation ◽  
Computational Simulations ◽  
Elastic Plastic ◽  
Modified Method ◽  
Plastic Materials ◽  
Elastic Plastic Material ◽  
Elastic Plastic Materials

Computational simulations of indentations in elastic-plastic materials showed overestimate in determining elastic modulus using the Oliver & Pharr’s method. Deviations significantly increase with decreasing material hardening. Based on extensive finite element computations the correlation between elastic-plastic material property and indentation has been carried out. A modified method was introduced for estimating elastic modulus from dimensional analysis associated with indentation data. Experimental verifications confirm that the new method produces more accurate prediction of elastic modulus than the Oliver & Pharr’s method.

Elastic and elastic-plastic finite element analysis of hollow tubes with axisymmetric internal projections under combined axial and pressure loading

2001 ◽  
Vol 36 (4) ◽  
pp. 373-390 ◽  
Author(s):  
S. J Hardy ◽  
M. K Pipelzadeh ◽  
A. R Gowhari-Anaraki
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Internal Pressure ◽  
Plastic Material ◽  
Axial Loading ◽  
Material Model ◽  
Pressure Loading ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Applied Loading

This paper discusses the behaviour of hollow tubes with axisymmetric internal projections subjected to combined axial and internal pressure loading. Predictions from an extensive elastic and elastic-plastic finite element analysis are presented for a typical geometry and a range of loading combinations, using a simplified bilinear elastic-perfectly plastic material model. The axial loading case, previously analysed, is extended to cover the additional effect of internal pressure. All the predicted stress and strain data are found to depend on the applied loading conditions. The results are normalized with respect to material properties and can therefore be applied to geometrically similar components made from other materials, which can be represented by the same material models.

Soil Modeling Using FEA and SPH Techniques for a Tire-Soil Interaction

2011 ◽  
Author(s):  
Moustafa El-Gindy ◽  
Ryan Lescoe ◽  
Fredrik O¨ijer ◽  
Inge Johansson ◽  
Mukesh Trivedi
Keyword(s):  
Surface Pressure ◽  
Particle Density ◽  
Plastic Material ◽  
Material Model ◽  
Shear Displacement ◽  
Physical Models ◽  
Element Analysis ◽  
Elastic Plastic ◽  
Vertical Loading ◽  
Fea Model

In recent years, the advancement of computerized modeling has allowed for the creation of extensive pneumatic tire models. These models have been used to determine many tire properties and tire-road interaction parameters which are either prohibitively expensive or unavailable with physical models. More recently, computerized modeling has been used to explore tire-soil interactions. The new parameters created by these interactions were defined for these models, but accurate soil constitutive equations were lacking. With the previous models, the soil was simulated using Finite Element Analysis (FEA). However, the meshless modeling method of Smooth Particle Hydrodynamics (SPH) may be a viable approach to more accurately simulating large soil deformations and complex tire-soil interactions. With both the FEA and SPH soils modeled as elastic-plastic solids, simplified soil tests are conducted. First, pressure-sinkage tests are used to explore the differences in the two soil-modeling methods. From these tests, it is found that the FEA model supports a surface pressure via the tensile forces created by the stretching of the surface elements. Conversely, for the SPH model, the surface pressure is supported via the compressive forces created by the compacting of particles. Next, shear-displacement tests are conducted with the SPH soil (as this test cannot easily be performed with an FEA soil model). These shear tests show that the SPH soil behaves more like clay in initial shearing and more like sand by exhibiting increased shearing due to vertical loading. While both the pressure-sinkage and shear-displacement tests still show that a larger particle density is unnecessary for SPH soil modeling, the shear-displacement tests indicate that an elastic-plastic material model may not be the best choice.

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