Ultrasonic fatigue tests were carried out on the plastic material Nylon 6. Special attention was devoted to the tempera- ture control in order to avoid physic-chemical transformation of this low melting point material. Under ultrasonic fa- tigue tests, important heat dissipation takes place at the narrow section of hourglass shape specimen leading to high temperature at this zone. The specimen was calculated to meet the resonance condition with the smallest dimensions at its narrow section, with aim to reduce the temperature gradient at this zone of this non heat conducting material. Tem- perature at narrow section was maintained lower than 45˚C using a cooling system with cooling air; under this condi- tion the ultrasonic fatigue tests were performed. Experimental tests were carried out at low loading range (9% - 12.5% of the elastic limit of material) in order to control the highest temperature and to avoid that specimen was out of reso- nance condition. Experimental results are analyzed together with the fracture surfaces and conclusions are presented concerning the ultrasonic fatigue endurance of this polymeric material.
The importance of plasma substitutes have been rising steadily. The main reason for its increasing use is handling with greater flexibility, therapeutic margin of safety, stability and compatibility, but their medical devices (containers) and their component materials may leach compound or have surface characteristics that may produce undesirable effects when used clinically. Due to least hazards of LDPE and most widely used plastic material in Plasma substitute biological reactivity tests of LDPE are performed to detect any unexpected and unacceptable leachable substance of plastic materials of bottles/containers which are stored at different temperature during study.In present studies biocompatibility testing of plastic material (LDPE) of two different plasma substitutes (polygelin) stored at different storage conditions at different time period did not show any eye irritation or eye injury or localized reaction in the test of eye irritation employed on rabbits. In the same way results of intracutanous test did not show erythema and edema on rabbit skin, which indicated that different plasma substitutes can be stored in LDPE containers at different temperature for their expiration time, shelf life or utility time restriction for hot and humid region of world for quality, safety, suitability, acceptability and efficacy.
In most cases, the main factor in selecting adhesives is their bond quality and the ability to undertake mechanical loading. Another factor is the status of the contact surfaces and its prepara- tion by etching, priming and grinding to remove coarse material, dirt, and grease gathered which can adversely affect the bond strength. These pro- cesses take time and require other resources . In this respect, as Selfix was designed to be water-soluble, the free molecules within the ma- terial make strong joints with others when dry- ing, thus making Selfix an adhesive in some cas- es. Apart from this, a thin layer of this material can increase the axial stress resistance against tensile and compressive loading. Another use is improved bonding since almost all the available surface area can be contacted and holes and air pockets avoided. A smooth surface hosts far more free molecules, which ensure proper adhesion, compared to an uneven one .
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Kim, 2007; Bergado and Teerawattanasuk, 2008; Yoo and Kim, 2008). The results of these investigations have provided important insight regarding collapse mechanisms for reinforced slopes, walls and embankments. The shear resistance of soil is a result of friction and interlocking of particles, and possibly cementation or bonding at particle contacts. Due to interlocking, particulate material may expand or contract in volume as it is subject to shear strains. If soil expands its volume, the density of particles will decrease and the strength will decrease; in this case, the peak strength would be followed by a reduction of shear stress. The stress-strain relationship levels off when the material stops expanding or contracting, and when inter particle bonds are broken. The theoretical state at which the shear stress and density remain constant while the shear strain increases may be called the critical state, steady state, or residual strength.
Due to these reasons expansive soils are generally poor material for construction. So to improve the engineering properties of soil, stabilization or reinforcement is done. Soil stabilization is the process of blending and mixing materials to improve engineering properties of soil like increasing shear strength, compressibility and permeability, thus improving load bearing capacity of a sub-grade to support pavements and foundations. For many years, engineers have used traditional additives such as lime, cement and cement kiln dust etc. to improve the qualities of readily available local soils. The stabilization of expansive soils with cement and lime is well documented. Cement stabilization nowadays is less appreciated because of the increasing cost of cement and environmental concerns related to its production. India being the second largest producer of cement has a very heavy impact on CO 2 emission. One can
It has been emphasized that it is only a matter of time before the reserves of conventional energy become ex- hausted *1+. Thus, mankind has to rely on the alternate energy sources. Conversion of waste plastic to fuel is one of such alternate energy sources. Due to the increase in generation of waste plastic, it is becoming a major stream in solid waste. After food waste and paper waste, plastic waste is the major constitute of municipal and industrial waste in cities. Even the cities with low economic growth have started producing plastic waste due to production of plastic packaging, plastic shopping bags, PET bottles and other goods/appliances which uses plas- tic as one of major components. Examples of plastic include polyethylene, polypropylene, nylon, polycarbonate, phenol formaldehyde, etc. *2+.
This chapter had covered the literature review of the project study. In this chapter, the literature review had introduced about the history of injection moulding, and also reviewed the topics such as injection moulding process, plastic defects, plastic material, Taguchi method and part shrinkage.
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The rate of panels’ plastic work can be obtained by differentiating equation (14) with respect to time, and consequently the history curves of their accumulated plastic work can be plotted. However, the major error will occur when using the assumption of rigid plastic material properties to describe the response of panels under dynamic impact loadings. As seen from Figure 11, the panels had remarkable elastic vibrations after reaching their peak deflections, proving that the elastic deformations cannot be ignored. The rigid plastic assumptions will replace the elastic state of strain with plastic flow strain, which will enlarge the stress during impact. Furthermore, the flow of plastic hinges will make the state of stress extremely hard to analyze. Figure 21(a) plots a typical time-dependent curve of panel’s plastic work, which surpassed the initial impact energy during impact. Also, after the deflection began to vibrate, the plastic work was still increasing. This is because the elastic vibrations were calculated as plastic flow, therefore the plastic work was overestimated. The comparison of obtained plastic work is shown in Figure 21(b), where a negative correlation between the dimensionless plastic work and impact velocities can be figured out. This is due to the fact that elastic deformations have their limitations. When the impact loadings were increased, the plastic work became the major way for the panels’ energy absorptions. It can be seen that the dimensionless plastic work of the panel under 115.6 m/s impact reached nearly 1 finally, meaning that the fraction of overestimated work was less than those under smaller loading conditions.
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fines the element mesh near the region of contact to al- low the hemisphere’s curvature to be captured and accu- rately simulated during deformation. The model uses quadrilateral, four node elements to mesh the hemisphere. The resulting ANSYS mesh is presented in Figure 1. The nodes on the axis of symmetry are fixed in radial direction. Likewise the nodes on the bottom of the hemisphere are fixed in both axial and radial direction. This boundary condition is valid for the modeling of as- perity contacts for two reasons: first, the asperities are connected to a much larger bulk material at the base; second, since the high stress region occurs near the con- tact, the boundary condition at the base of the hemi- sphere will not greatly affect the solution because of Saint Venant’s principle. The bilinear isotropic harden- ing (BISO) option in the ANSYS program is chosen to account the elastic-plastic material response for the sin- gle asperity model. The rate independent plasticity algo- rithm incorporates the von Mises criterion. Tangent modulus is assumed as zero for validating the results with other elastic perfectly plastic models. The KE model uses a maximum of 2944 nodes and JG model uses a constant of 11,101 elements for their analysis. However the present work uses a maximum of 11069 elements for the radius of 1 mm. The mesh density is iteratively increased until the contact force and contact area differed by less than 1% between iterations. In addi- tion to mesh convergence, the model also compares well with the Hertz elastic solution at interferences below the critical interference. The contact force of the model dif-
the end of the gauge section. The second assumption is equivalent to saying that the shoulders and endcaps do not deform, which might be a good approximation to the real behaviour, and instead just act as point masses on the end of the gauge length, Fig. 2(c). More realistically, some undefined portion of the shoulders deforms significantly, Fig. 2(d). In a perfect specimen of an elastic perfectly plastic material, plastic deformation would be confined to the gauge length, but because the radial inertia increases the axial stress required to yield the gauge length, plastic deformation would in fact enter the shoulders in a real tensile scimen deformed at high rates of strain.
HDPE plastic has few properties that make it suitable as a packaging and manufacturing product. It is extremely stronger than existing polyethylene, serves as a very effectively against humidity and then remains solid at room temperature. It resists against rot and other chemicals corrosion. It was easily recyclable and can be used for making a new product again. Recycled HDPE creates no harmful extrication during its production or during its usage by the user or consumer. Also, HDPE puncture no toxic chemicals into the ground or water.
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For mixing the ingredients of road mix, dry process was adopted. In this process, waste plastic is mixed with aggregates and blends of polymer modified aggregate are prepared by mixing bitumen in it. These blends are later tested in laboratory and required optimum results are obtained. The blends using aggregates and bitumen were prepared along with the use of different percentage of waste plastic in it separately (See Figure 4) and were kept for water bath at least 24 hrs. Later these blends were tested under marshal stability apparatus to check its stability for road pavements.
Silvia Smeu, Andrei Gal and Cătălin Badea has concluded that” The continuous search for affordable and environmental friendly housing, led to investigations into new building masonry materials. Clay is a natural resource of the planet and one of the most common and has been recently “rediscovered” as anecologically sound and healthy building material. Due to problems with shrinkage and swelling of clays and changes in material properties, we tried to stabilize the mixtures realized with clay using cement, lime and sand as binder, and we also added sawdust in each batch made. The tests that we made were concerning: apparent density, bending tensile strength and compressive strength. By using clay and sawdust in this “rediscovered” building material, results a good impact on environment. The values obtained for compressive strength were within the acceptable standards for clay masonry units”.
The plastic injection molding process engaged the injection of a plastic material melt into a closed mold, at point the plastic cools and solidifies to form a specific product. The action that takes place is much like a three phase process comprising filling, packing and cooling phase. In its simplest form, is like the operation of a plunger needle that a barrel contains heated plastic that is injected by used of a plunger or auger device into a closed mold that contains a machined, reverse image of the desire product. While this may seem simple, the process actually involves many individual activities and parameters that must be tightly controlled to produce a high-quality product at a reasonable cost. The primary advantage of this process is that many functions and features can be incorporated into the product design. This process will minimize, or eliminate, the amount of secondary work required to produce the same product in other ways or using other materials. Its popularity is typified by the numerous products produced in this way at present time (Brydson, 1999).
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f( σ ) = 0 (22) because numerical procedures for calculation of the slip lines and velocity field in the plastic region give unique relation between vectors σ and f. Equation (22) with N ≤ 20 was solved using numerical procedures  for Broyden’s method .
The softening point is increase when plastic percentage is increases modifiers bitumen and this is due to the bitumen becomes increasingly viscous. Softening point of VG 30 grade bitumen, increase to more than 55 0 c by addition of 9 percent fibers. Therefore 8 percent should be the upper limit for VG 30 bitumen. The results show that lower percentage of plastic fibers can be used in road construction satisfactorily.
Given the high price of the raw material and usually relatively low production volumes, numerical simulation can be a very useful tool in this field in helping to establish a reliable production process, both to determine the feasibility of a given process and to optimise the process parameters and tooling geometry beforehand, minimising the need for costly trial and error testing. There have been some attempts in recent years to develop bespoke constitutive models for HCP metals, as found in  to , however, a key feature of a numerical method applied in an industrial environment is the ability to identify the necessary material parameters promptly and with readily
The R5 procedure is composed of several steps, which need to be completed in order to fully assess the integrity of a component. A schematic flowchart is presented in Fig. 1 to show the R5 procedure  for structural integrity assessment of defect-free components and LMMF capabilities in support of it. The main objective of the LMMF is to evaluate key design limits and parameters required in the R5 procedure in an efficient and accurate way by various of direct methods. In comparison with full inelastic analysis, which needs detailed material constitutive equations and load histories, the direct methods in the LMMF do not have high computational cost and inherent convergence issues of detailed step-by-step analysis. It can be seen from Fig. 1 that the direct methods within the LMMF are able to assess safe margins against the plastic collapse and creep rupture, if creep is significant, in an accurate and efficient way, without relying on conservative assumptions or complex constitutive formulations. As depicted in Fig. 1 the LMMF also provides numerical procedures to calculate both shakedown and ratchet limits for any arbitrary load history, providing upper and lower bound solutions. When creep is relevant, but the associated dwell time is too short to have a stress relaxation, the overall load history involving a constant residual stress filed is similar to shakedown condition. For this case, the LMMF provides a rapid cycle creep analysis to calculate the creep strain rate for each load cycle, which is more accurate than the R5 procedure . In order to evaluate the pure fatigue and creep-fatigue damages, the LMMF provides DSCA and eDSCA to estimate the steady state cycle, considering pure plasticity or full creep and cyclic plasticity interaction, respectively. The creep-fatigue damage can be assessed by the obtained total strain and stress ranges of the steady state cycle, the start of dwell stress, the associated stress drop and creep strain during the creep dwell. This approach is different from the R5 procedure, which relies on approximations to calculate the aforementioned quantities. Hence, the use of the LMMF safely reduces conservatisms, but also improves the understanding of the cyclic response of the structure by characterizing complex mechanisms such as creep-ratchetting or cyclically enhanced creep.
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Density is a material property which is of prime importance in several weight sensitive applications. Polymers are well known for their low density. The low densities of polymer composites are found to replace the conventional metals and materials in many engineering applications. Density of a composite depends on the relative weight proportion of matrix and the reinforcing components. The theoretical and experimentally measured densities of polyester composites reinforced with TiO 2 , along with the
The AM produced parts can be used and post processed (milled, drilled, coated) like any other standard industrial part. Especially in metal, AM produced parts often exceed some of the mechanical property values of those machined from standard bulk material. Another benefit is the outstanding material efficiency of most AM processes. Scrap rates for AM parts are usually below 5%, compared to scrap rates of more than 90% with many complex milled parts. With a decline in available raw material and rising costs this material efficiency will remain a major advantage in the long term.