Strength of materials

Results of long-term hydrostatic strength study of piping systems made from polyethylene with increased temperature resistance PERT type II of Hostalen 4731B without reinforcement are presented and discussed in this paper. The different approximations of durability curves and various equivalent stress measures are considered and compared. An analytical expression for the maximum allowable internal pressure as function of service life of pipes, temperature, geometrical parameters of pipe cross-section and material properties is given. Pipes without reinforcement with nominal outer diameters from 32 mm to 225 mm were analyzed to assess long-term hydrostatic strength using equivalent stress, provided that there is no change in mechanism of damage accumulation. This allowed us to use linear extrapolation into area of long service life. The results indicate possible use of pipes SDR7.4 in heating networks for 50 years with heat transfer fluid parameters of 95 °C and internal pressure of 1 MPa.

Metal matrix composites with high interface density are produced via severe plastic co-deformation of multiphase alloys. 1–15 Corresponding compounds are first prepared by liquid or powder metallurgy3–12 or through restacking solids of different composition. 2 Subsequent extreme straining, to promote intense microstructure refinement, proceeds by wire drawing, ball milling, accumulative roll bonding, damascene forging, equal channel angular extrusion, friction, or highpressure torsion. 7

Semiflexible pavement (SFP), a composite pavement, is formed by filling into a very open porous asphalt skeleton a specifically designed water consistency fluid mortar with a very high early and 28-day strength. The amalgamation of both components will produce a SFP where it will replace the conventional wearing course. The main goal of this investigation is to study the effect of various aggregate gradations towards producing SFP. These include determining the optimum binder, volumetric properties, and durability and strength of each aggregate gradation. The final results were statistically analyzed and two factor variance analyses (ANOVA) were performed to check on the significance at certain confidence limits. The results confirmed that different aggregate gradations significantly affect the properties mentioned.

Concrete is a construction material composed of Cement, fine aggregate, coarse aggregate, and water with or without admixtures. The concrete industry is one of the heaviest consumers of natural resources due to which sustainability of concrete industry is under threat. The biggest problem facing the concrete industry is the environmental and economic concern. In this research Paper , the Ordinary Portland Cement (Grade 43) has been partially replaced by Waste Glass Powder (GLP) and in Second stage Natural sand and cement replaced by stone dust and waste glass powder accordingly in the proportion of 0%, 10%, 20%, 30%, 40% & 50%, at constant 15 % of Waste glass powder by weight of M-30 grade concrete. Concrete mixtures were produced, tested and compared in terms of Compressive Strength, Split Tensile Strength and Flexural Strength of the conventional concrete at a period of 28 days. It is observed that glass Powder and stone dust gives better results as compared to conventional concrete. It is found that strength and workability of mixes increases significantly when glass Powder and stone dust is used.

This paper presents a study for the development of first- and second-order tool-life models at 95% confidence level for turning high strength steel. The tool-life models are developed in terms of cutting speed, feed rate, and depth of cut, using response surface methodology and design of experiment. The effects of the main cutting variables (cutting speed, feed, and depth of cut) on tool life have been investigated by the application of the factorial design method. All of the cutting tests were performed using uncoated carbide tools under dry conditions. Tool-life contours have been generated from these model equations and are shown in different plots. Dual-response contours of metal removal rate and tool life are shown also. The results are presented in terms of mean values and confidence levels. © 1998 Elsevier Science S.A. All rights reserved.

http://ac.els-cdn.com/S0924013697004354/1-s2.0-S0924013697004354-main.pdf?_tid=7ea8c4dc-1d34-11e4-b1a5-00000aab0f6c&acdnat=1407307382_b0d7d5d96bfabc738bde8c6860d2acd2 
http://www.sciencedirect.com/science/article/pii/S0924013697004354

A brief review of the geology of the tar sand areas of Nigeria is given. Analysis shows that the tar sand used for the tests consists of a well graded silty sand (cmf) with about 5% clay; and 3–5% bitumen. Results presented show a very high in situ compressive strength of about 450 kN/m2, a high ratio of tensile to compressive strength of about 22%, peak shear strength parameters of Cp′=15kN/m2and φp′ = 19° and residual parameters of Cr =0, φr = 18°. The compacted tar sand behaved like an overconsolidated soil with a preconsolidating pressure, Pc of 140 kN/m2. In general, the results of the in situ strength tests indicate that the Nigerian tar sand behaved as a soft sandstone.

The paper deals with the application of fiber reinforced polymer (FRP) laminates or fabrics as shear strengthening materials for reinforced concrete beams. The study aims at increasing the experimental database on shear strengthening of concrete using composites and, most ...

The paper considers one of the most difficult problems of determining the design schemes for architectural designs. The analysis of existing methods of compiling calculation schemes is carried out depending on the composition of structural elements , the material of the structure and its configuration. The criteria for the correspondence of the design scheme of the real structure and its elements are revealed. The results of the study make it possible to conclude that the criterion of conformity is introduced by the quantitative index for the mass of the structure and its elements. It is proposed to introduce the mass of the structure or its elements as the main set parameter for determining the calculation system in the stretching or compression zone.

Hydrogen embrittlement in 304L austenitic stainless steel fabricated by laser powder-bed-fusion (LPBF) was investigated and compared to conventionally produced 304L samples with two different processing histories; casting plus annealing (CA) and CA plus thermomechanical treatment (CA-TMT). Interestingly, no significant difference in the amount of deformation-induced α ′ martensite between the LPBF and CA-TMT samples was observed, suggesting that the solidification substructure in the LPBF sample enhanced the strength without promoting the harmful hydrogen embrittlement effect. These results are discussed in terms of the chemical in-homogeneity, hydrogen-assisted cracking behavior, and hydrogen diffusion and trapping in the present 304L samples.

In the Upper Peninsula of Michigan, over 500 million tons of copper rich rock were removed from mines and treated in chemical baths to extract copper. Toxic substances have been seeping into the watersheds from the resultant waste stamp sands. Recent work on developing a circular economy using recycled plastic for distributed manufacturing technologies has proven promising, and this study investigates the potential to use this approach to form stamp sand and acrylonitrile styrene acrylate (ASA) composites. Specifically, this study found the maximum amount of stamp sand that was able to be added to waste ASA by mass with a single auger recyclebot system for compounding was below 40%. The mechanical properties of the composite were evaluated up to 40%, and the addition of stamp sand reduced the material's ultimate tensile strength by about half compared to the strength of raw recycled ASA, regardless of the percent stamp sand in the composite. However, this strength reduction plateaus and the tensile strength of the ASA and stamp sand composites can be compared favorably with acrylonitrile butadiene styrene (ABS) at any level. This makes waste ASA-stamp sand composites potential replacements for outdoor applications of ABS as well as some current ASA applications. These results are promising and call for future work to evaluate the technical, economic and environmental potential for waste ASA-stamp sand composites.

As basic parameters in speech processing we regard pitch, duration, intensity, voice quality, signal to noise ratio, voice activity detection and strength of Lombard effect. Taking in account also adverse conditions the performance of many published algorithms to extract those parameters from the speech signal automatically is not known. A framework based on competitive evaluation is proposed to push algorithmic research and to make progress comparable.

Machinability assessment of nickel base super alloy (inconel 718) in turning operations has been carried out using coated and uncoated carbide inserts under dry conditions. Inconel 718 is one of the most difficult-to-machine materials because of its low thermal diffusive ...

This study explores the potential to reach a circular economy for post-consumer Recycled Polyethylene Terephthalate (rPET) packaging and bottles by using it as a Distributed Recycling for Additive Manufacturing (DRAM) feedstock. Specifically, for the first time, rPET water bottle flake is processed using only an open source toolchain with Fused Particle Fabrication (FPF) or Fused Granular Fabrication (FGF) processing rather than first converting it to filament. In this study, first the impact of granulation, sifting, and heating (and their sequential combination) is quantified on the shape and size distribution of the rPET flakes. Then 3D printing tests were performed on the rPET flake with two different feed systems: an external feeder and feed tube augmented with a motorized auger screw, and an extruder-mounted hopper that enables direct 3D printing. Two Gigabot X machines were used, each with the different feed systems, and one without and the latter with extended part cooling. 3D print settings were optimized based on thermal characterization, and both systems were shown to 3D print rPET directly from shredded water bottles. Mechanical testing showed the importance of isolating rPET from moisture and that geometry was important for uniform extrusion. The mechanical strength of 3D-printed parts with FPF and inconsistent flow is lower than optimized fused filament, but adequate for a wide range of applications. Future work is needed to improve consistency and enable water bottles to be used as a widespread DRAM feedstock.

— Since from Roman times concrete is main material for construction and infrastructures but its combinations are differencing day to day, at present situations many types of concretes are funded out by number of researchers. Now I like to give a brief description regarding the TRANSPARENT CONCRETE. It is a combination of fibre-optics and fine concrete. Mainly transparent concrete consists of only fine aggregate. Materials used in transparent concrete are sand, water, cement and optical fibres. Transparent concrete is also known as translucent concrete or light transmitting concrete. Replacement of translucent concrete in construction results in art design. Transparent fibre has a nature of fire resistance. Transparent concrete blocks are suitable for pavements, floors and load-bearing walls. Mainly partition walls, where sunlight is more available. Present our research work carried to find the transparent percentage compared to strength.

The open source introduction of fused filament fabrication (FFF) enables distributed manufacturing of consumer products. However, with a wide range of low-cost FFF 3-D printers and settings possible, there is a lack of information on the variability in printed mechanical properties. This paper utilizes a large pool of 47 user-assembled 3-D printers to quantify the mechanical property variations of ultimate tensile strength (UTS) and yield strength of FFF printed components using ASTM D638-14 horizontally-oriented Type I and IV geometries for poly lactic acid (PLA). The results indicate that utilizing Type IV tensile test piece geometry may overestimate the UTS relative to the Type I. Furthermore, anisotropic mechanical property variances were quantified for Type IV specimens (vertical and horizontal orientations). Vertical tensile specimens had an ultimate tensile strength 47.9% less than horizontal. Finally, the abundant supply of PLA 3-D prints suggest open-source printers assembled by individual operators can produce quality plastic components although the mechanical performance of the given part can vary dramatically based on the operator selection of printing parameters that provide a visually acceptable part.

The characteristic value of the strength of annealed float glass, to be used in structural calculations, is assessed by standards on the basis of a classical experimental campaign using the Coaxial Double Ring (CDR) test with additional overpressure. Experimental data were regressed according to the 2-parameter Weibull distribution, assuming that the induced state of stress is equibiaxial in practice. We show that, by splitting the data in two categories according to the surface under tensile stress (either the ''tin" or the ''air" side), a more accurate statistical interpretation can be obtained. Comparisons with the normal and log-normal distributions are made with the chi-square goodness-of-fit test. Moreover, we observe that the calibration curve suggested by the test standard is not precise, and that the stress state in the testing configuration is not equibiaxial. Therefore the rough data need to be further corrected and re-scaled to a common reference condition, according to a criterion of equal failure probability, by determining the effective area of the loaded specimen. Doing so, the considered statical distribution are able to fit to the data with much more accuracy. Considering that for very low failure-probabilities the tails of the statistics are the most important, and observing that the 2-parameters Weibull function fails to interpret a lower bound for the strength of glass that can be inferred from experiments, the use of a 3-parameter Weibull distribution is proposed. After having derived the corresponding expressions for the effective area, we present a new statistical characterization of glass strength that provides the best fit with the experimental data, at least for the air-side.

Within the framework of the ‘Component Specific Analysis of Mechanical Behaviour’, the nuclear codes and standards, e.g. KTA Standard KTA 3201.2 on Components of the Reactor Coolant Pressure Boundary of Light Water Reactors (Design and Analysis) allow a simplified stress and fatigue analysis for piping by applying the stress index method. The equations supplementary to present KTA Standard given in this context can be used for the consideration of the thermal loads arising from piston flow but not of those from thermal stratification. Thermal stratification occurs e.g. in the surge line of pressurised water reactors during start-up and shut-down processes. This phenomenon is explained and its effects are described. The equations supplementary to the present KTA Standard are derived which enable the consideration of the load case ‘thermal stratification’ in the simplified stress and fatigue analysis. Their applicability is demonstrated by a numeric example.

The substance of good quality cement is the necessity of right usefulness. Under various circumstances cement of various level of usefulness is required. A serious level of usefulness is needed in circumstances like profound bars, dainty segments with high level of fortification, shaft and segment intersections, siphoning of cement, tremie cementing, blistering climate cementing and so on The ordinary techniques for improving work¬ability are by improving the degree or expanding the amount of fine total or by expanding the concrete amount. In this study we are presenting review of literatires re;ated to utilization of plasticizers in concrete and its beneficial effects.

In this study, the parametric design and contact analysis of composite spur gears are
investigated numerically. Composite gear provides an adequate strength to weight ratio, more hardness, durability and low maintenance cost. It is emerging better alternatives for replacing metallic gears. The finite element model of spur gear is developed with the assistance of the Ansys software. In this study each design factor such has stress distributions, strain and deformation are considered to compare composite gear with steel and polymer gears. An APDL gear model has been developed for the design evaluation and comparison study.