...floor-supports as well. The structural strength and stiffness of the fuselage must be high enough to withstand these loads. According to the British Civil Airworthiness Requirement, safety factor of at least 1.5 times the normal working load for aircraft fuselage structure must be used. Failure is catastrophic, the limit load occurs during every flight and the fuselage is not only subject to pressurization forces. The static strength of the fuselage therefore incorporates a larger safety factor. A reduced factor of safety from the stated factor will preclude failure due to creep and provide adequate protection against tear propagation. Besides, the structure must be able to support limit loads without permanent deformation. At any load up to limit loads, the deformation may not interfere with safe operation and this applies in particular to the control system. The structure must be able to support ultimate loads without failure for at least three seconds. Another important construction factor of fuselage is protection of passenger in crash. Transport aircraft carrying as many as 800 passenger on the drawing board. The structural properties of the strong cabin floor board maintain...
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...applied that will exceed the yield strength of the material. The material actually gets stronger the more it is deformed plastically. This is called strain hardening or work hardening. Many metal forming processes are suitable for processing large quantities (i.e., bulk) of material, and their suitability depends not only upon the shape and size control of the product but also upon the surface finish produced. There are many different metal forming processes and some processes yield a better geometry and surface-finish than some others. Metal forming processes can be classified under two major groups. Bulk deformation processes and sheet metalworking processes. Bulk deformation is characteristic in that the work formed has a low surface area to volume ratio. In sheet metalworking the metal being processed will have a high surface area to volume ratio. Among the bulk Deformation, there are rolling, forging, extrusion and drawing method. Rolling is a metal forming process that deforms the work by the use of rolls. Rolling processes include flat rolling, shape rolling, ring rolling, thread rolling, gear rolling, and the production of seamless tube and pipe by rotary tube piercing or roll piercing. Forging is characteristic in the use of dies to compress and shape a work piece. The die may be flat or may contain an impression of a certain geometry. Extrusion involves forming by forcing metal through a die opening, producing work of variable length and constant cross section. Drawing...
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...CHAPTER I INTRODUCTION Background of the Study Structural materials can be categorized in many ways in many different ways. One of the most common is by the nature of their failure. Materials, such as steel, after reaching their elastic limit, deform plastically before failing. Such materials, where reasonably large plastic strains are observed, are broadly categorized as ductile. On the other hand, those materials that exhibit little or no plasticity are in contrast termed brittle. In structural design, ductile materials are usually preferred, because failure is rarely sudden and catastrophic. Once the material has yielded, large observable strains will occur before total collapse of a structure. Steel, the most common primary structural building material, generally behaves in a ductile fashion. However, during the World War II, over 200 steel ships suffered serious brittle fracture, often at relatively low stress levels. It was observed that brittle behavior, in normally ductile materials, almost always occurs in regions of elastic stress concentration, where some constraint exists to prevent plastic stress redistribution (McGuire, 1968) Following these experiences, designers realized that brittle fracture in steel could be avoided by sensible detailing. This is also true of reinforced concrete. Concrete itself, is a brittle composite, but with the addition of reinforcements concrete it behaves in a ductile fashion. In an earthquake-prone areas, where designing for ductility...
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...first question is based around work hardening, the changes in the atomic structure as a result thereof and the reason why some materials are more susceptible to work hardening than others. The second question is based on the process of embrittlement, as well as listing a few different ways in which embrittlement can occur. The third and last question is based on the significance of heat affected zones, with special emphasis on the effects with regards to steel. Work hardening Work hardening is a phenomenon found in metallic materials, where deformations in the metals have led to the metal itself becoming strengthened, or harder as such. The deformations which cause this effect are called plastic deformations, which means that the metal material was stressed beyond the point where elastic deformation takes place, thereby resulting in a permanent deformation in the crystalline structure of the metal material. These plastic deformations are caused by high heat exposure for a specific minimum length of time, causing the molecules within the crystalline structure to rearrange themselves. A few common physical processes which take place on metals and can cause this effect are as follows: hammering, bending, rolling, drawing, shearing, squeezing or collisions between metals for example. All of the above would result in some form of work hardening in metallic materials susceptible to it, due to the fact that large forces are applied during those processes, over relatively small areas...
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...Unit Name: Properties and Applications of Engineering Material Unit No.: 19 Task: 1 Describe the principles of the modes of failure known as ductile/brittle fracture, fatigue and creep. Brittle fracture: In the brittle fracture extensive plastic deformation and heat absorption before a fracture. In the brittle fracture crystalline materials, fracture can be occurring by cleavage as the result of tensile stress, acting normal to crystallographic planes with low bonding. In the amorphous solid by contrast, the lack of a crystalline structure results in as fracture, with cracks proceeding normal to the applied tension. http://hycalin.nl/line-types/chain/ Ductile fracture: In the ductile fracture, plastic deformation takes place before fracture. The terms rupture or ductile rupture describes the ultimate failure of the ductile materials loaded in tension. Many ductile metals, especially materials with high purity, can sustain very large deformation of 50 to 100% or more strain before fracture under loading condition and environmental condition. The strain at which the fracture happens is controlled by the purity of the materials. At room temperature, pure iron can undergo deformation up to 100% strain before breaking, while cast iron or high carbon steels can barely sustain 3% of strain. http://lrrpublic.cli.det.nsw.edu.au/lrrSecure/Sites/Web/tensiletesting/lo/03whatdoesitmean/03whatdoesitmean04.htm Fatigue: Fatigue is a subjective feeling...
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...Background and Aim Creep is defined as the ‘’ time-dependent and permanent deformation of materials when subjected to a constant load or stress’’ (Callister 2011, p.265). The aim of this experiment is to find the creep rate of a rubber in tension. Rubbers are classified as elastomers, elastomers are polymers which have a high degree of crosslinking and it is this crosslinking that allows elastomers to return to their original shape after deformation. Elastomers exhibit viscoelastic behaviour; viscoelastic materials have both viscous and elastic characteristics when undergoing deformation. When a load is applied to a viscoelastic material the deformation is time dependent under constant temperature, this means that the strain increases with time. Figure 1: The creep strain behaviour of a viscoelastic material under constant stress. The strain increases with time while stress remains constant. As the load is applied the strain increases instantaneously, this is the elastic behaviour of the material. In the recovery stage the strain does not return to zero even after a considerable amount of time, this illustrates the viscous property of the material. [Diagram] At: http://dspace.jorum.ac.uk/xmlui/bitstream/handle/10949/1033/Items/T838_1_section23.html (Accessed on 25/10/2014) A typical creep test involves subjecting a specimen to a constant load or stress while keeping the temperature constant. Procedure Figure 2: An illustration of the experimental set-up. Figure 2: An...
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...1.0 INTRODUCTION 1.1 Beam Deflections 1.2 Theory - Calculations DeflectionF formula for the load given above: A determination of flexural stress yields: When rectangular it is Where; δ = Deflection (mm) E = Coefficient of Elasticity L = Span (mm) I = Inertia Factor Mb = Moment of flexure (Nmm) F1 = Load occasioned by weight Wb = Resistance to flexure (mm3) of Load Device (N) σb = Flexural Stress (N/mm2) F = Load of occasioned by additional weight (N) 1.3 Objectives * To investigate the relationship between load, span, width, height and deflection of a beam placed on two bearers and affected by a concentrated load at the center. * To ascertain the coefficient of elasticity for steel brass and aluminium 2.0 METHODOLOGY 2.1 Procedure - Experiement 1A * Investigate the relationship between load and deflection. 1) Set the bearers so that a span of 600 mm is obtained. The interval between each groove on the shafts of the apparatus is 100 mm. 2) Place a test specimen with dimensions of 4 x 25 mm, on the bearers and mount the load device in the center of the test specimen. 3) Set the testing device so that the top of the gauge is centered on the upper plane of the load device. Lower the gauge so that its small hand is at about 10 and set the gauge to zero by twisting its outer ring. 4) Load the weights as shown in the table below and read off the deflection...
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...20.04 | 20.33 | 40.37 | 4. | 21.7 | 21.96 | 43.66 | 5. | 21.03 | 20.34 | 41.37 | * 3% reduction in each pass * Total thickness reduction= 15% Specimen 4 Thickness= 1.4+0.006=1.406mm Indentation Hardness test Indentation Force=20N Specimen 1: I. 154HV II. 157HV III. 157HV Average Hardness= 157 HV Specimen 2: I. 162HV II. 160HV III. 159HV Average Hardness= 160.33 HV Specimen 1: I. 169HV II. 174HV III. 174HV Average Hardness= 172.33 HV Specimen 1: I. 184HV II. 183HV III. 181HV Average Hardness= 182.66 HV Conclusion: We observed that- * As we deform the material hardness increases. * Metals harden due to deformation at room temperature (cold working). * Grain boundaries, impurities, precipitates act as barriers or obstacles to the movement of dislocations. Dislocations get piled up at the grain boundaries. * To overcome the barriers and cause...
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...Q3. How does increased loading change L, W, and t? When F doubles from 4.0 N to 8.0 N for the small rubber band, does the deformation, L-L0, also double? When F doubles from 4 N to 8 N for the large rubber band, does the deformation also double? As the load increases, L increases and W and t decrease. From 4 N to 8 N, the deformation does not double; it doubles from 1N to 4N, and from 2N to 15N. The deformation rate slows as more force is applied. From 4N to 8N on the larger rubber band, the deformation does not double either. Both the small and large rubber bands deformed at approximately the same rate. Q4. What is the reason for the “2” in the cross-sectional area computation in Tables 2 and 3? Since values for width and thickness were only obtained for one side of the rubber band, they must be multiplied by 2 to account for the other side. However, the rubber band used in our experiment was cut, so we did not perform this calculation. In this lab, rubber bands were used to represent tendons to show...
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...CAE Software of Twin-Tubes Shock Absorber Outer-Characteristic Changcheng Zhou, Jie Meng School of Traffic and Vehicle Engineering Shandong University of Technology Zibo 255049, China greatwall@sdut.edu.cn Abstract The pathway throttle and local throttle loss of oil flow in telescopic shock absorber were analyzed, and the pathway loss coefficient and equivalent length of piston holes were studied. According to the thickness and the pre-deformation of throttle slice, and the throttle holes area, the velocity points of valve opening were researched and the analytic formulas of shock absorber velocity when valve opening were given. With the velocity points of valve opening, the model of shock absorber outer characteristic was established by piecewise linear math function. Based on this, the CAE software for shock absorber outer characteristic was developed. A practical example of simulation of shock absorber outer characteristic was given with this CAE software, and the performance test was conducted to verify the CAE software. The results show that the CAE software is reliable, and the values simulated is close to that tested. 1. Introduction The shock absorber of automobile is one of the most important components of suspension system, and plays a vital role in the driving process of vehicles[1,2]. The characteristic of shock absorber influences driving smoothness and ride comfortableness of vehicles[3]. The shock absorber used most commonly on ...
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...PHSC107 L16-Rock deformation Detailed need to know What you need to know – get more detail on these areas from textbooks / readings – as detailed on moodle page. Crustal deformation – a process acting on the lithosphere. Driven by plate tectonics. Orogenesis –(mountain building – Oro = mountain) – large scale bending, breaking, stretching etc. Application of stress to rock • Change in shape = deformation strain. Brittle or plastic failure. • Creates joints, folds, faults, foliation. Fractures can be offset or not. • How deformation affects rocks – by translation, rotation, distortion Strain • Change in shape • elastic strain (reversible change) • Permanent strain – brittle & ductile deformation (non-reversible) • Cause of deformation – stress – force acting on a rock – often a large scale tectonic origin. Stress is force per unit area. Think of the non-metric measure PSI – (pounds per square inch) Stress • Compression – squeezing, shortening or contraction, or pushing together. Think continental collision – Himalayas formation. • Extension – tension, stretching, pulling apart. Tends to thin the crust – think the Taupo Volcanic zone which is extending at 7 mm a year. The lithosphere is thin allowing magma to reach the surface. • Shear – sliding past, strike-slip. Blocks of rock slide past each other – the surface is neither thickened or thinned. Think the Alpine Fault. Deformation structures (brittle) – for these, need to be...
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...Clays and Clay Minerals, Vol. 49, No. 5, 410–432, 2001. BASELINE STUDIES OF THE CLAY MINERALS SOCIETY SOURCE CLAYS: INFRARED METHODS ´ JANA MADEJOVA AND PETER KOMADEL Institute of Inorganic Chemistry, Slovak Academy of Sciences, SK-842 36 Bratislava, Slovakia INTRODUCTION Infrared (IR) spectroscopy has a long and successful history as an analytical technique and is used extensively (McKelvy et al., 1996; Stuart, 1996). It is mainly a complementary method to X-ray diffraction (XRD) and other methods used to investigate clays and clay minerals. It is an economical, rapid and common technique because a spectrum can be obtained in a few minutes and the instruments are sufficiently inexpensive as to be available in many laboratories. An IR spectrum can serve as a fingerprint for mineral identification, but it can also give unique information about the mineral structure, including the family of minerals to which the specimen belongs and the degree of regularity within the structure, the nature of isomorphic substituents, the distinction of molecular water from constitutional hydroxyl, and the presence of both crystalline and non-crystalline impurities (Farmer, 1979). The interpretation of the absorption spectra of the Source Clays in the middle-IR (MIR) region (4000– 400 cm 1) given here follows those of Farmer and Russell (1964), Farmer (1974a, 1979) and Russell and Fraser (1994). In addition, reflectance spectra in the near-IR (NIR) region (11,000–4000 cm 1), where overtones...
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...from fear of falling while walking or doing easy tasks? You will be glad to know you are not alone. Bone and joint disease like osteoporosis and arthritis affect thousands of people in the United States and around world. Osteoporosis is a disease that causes bones to become porous and brittle. Porous, brittle bones are fragile, and prone to fractures from falls, bending over or even coughing (Osteoporosis, 2011). Osteoarthritis is the most common form of arthritis. Osteoarthritis a disease where the cartilage that covers the ends of bones deteriorates, and as the cartilage wears away the bones are exposed, and rub against each other (What is osteoathritis, 2011). This can be very painful, and can cause deformation. If there is deformation, the joints can no longer function smoothly. TO Download Complete Tutorial Hit Purchase Button HCA 240 Week 4 Radio Ad ( Material ) Get Tutorial by Clicking on the link below or Copy Paste Link in Your Browser https://hwguiders.com/downloads/hca-240-week-4-radio-ad-material/ For More Courses and Exams use this form ( http://hwguiders.com/contact-us/ ) Feel Free to Search your Class through Our Product Categories or From Our Search Bar (http://hwguiders.com/ ) Radio Ad Hello there! Many Americans...
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...international literature there is often confusion between the terms Modulus of Elasticity EYoung and Modulus of Deformation EDef for homogenous, isotropic masses, which, sometimes, plainly referred as Modulus E, without any further explanation. In this paper a distinction between the EYoung and the EDef is being done and the interest is concentrated in the Plate Bearing Test, which is commonly used in highway earthworks. Moreover, a soil classification diagram is given, in which the soils are classified by their shear strength parameters and their behavior, as totally elastic or elastoplastic, under specific loading applied by rigid circular plate. Finally, a method for the estimation of the soil parameters is proposed, using only the in-situ Plate Bearing Test. The study and the documentation were supported by a presentation of theoretical examples, based on the Finite Element Method. 1. INTRODUCTION In highway earthworks the knowledge of the Modulus of Elasticity of the soils is very important, whether the projects are in the stage of design, construction or compaction check and this is required to be obtained by an easy manner. Due to the complexity and difficulty in determining the Modulus of Elasticity in the laboratory by the Triaxial Test, which is usually not available on the worksite, the common practice for the designer is to determine the Modulus of Deformation with the in situ and easier Plate Bearing Test. It must be mentioned that, though the soils under load...
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...INTRODUCTION 1.1 Motivation Materials with small grain sizes have been the focus of attention for scientists and engineers since it has been proved by the work of Hall [Hall51] and Petch [Pet53] that strength increases as we decrease the grain size of the material. This finer grain size also helps in achieving superplastic deformation at higher strain rates and improves the fracture toughness of the material. Some of the traditional methods involving mechanical processes lead to a grain size above 10 µm. In present scenario, some of the techniques also lead to a grain refinement to submicron or nano range like ball milling, vapour deposition etc. But the techniques are not appropriate for large scale applications as they...
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