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Young structural materials

Structural materials of the ultraprecision machine tools require low thermal expansion, high Young s modulus, and low density. In order to meet such requirements, various kinds of ceramics are widely applied to the machine tool structure, such as the bed, columns, top beams, and nano-motion system. Various remedies for reduction of thermal error (Shinno 2010) are also important. In addition, the main frame structure is constructed on an active vibration isolation system installed inside a temperature-controlled enclosure. [Pg.1276]

The typical ranges of the modulus of elasticity (Young s modulus), flexural strength and fracture toughness of selected structural materials are displayed in Figure 5.1. [Pg.124]

The elastic modulus, or Young s modulus, is a coefficient of proportiOTiality (elastic strain constant) between the stress and deformation below the elastic limit of the material (Fig. 1.8). The elastic modulus is an important mechanical characteristic of structural materials it is closely related to strength, hardness, and abrasion resistance. Materials with a high elastic modulus value have high values of strength and hardness. [Pg.15]

Introduction. Thermoplastic elastomers such as polyolefin copolymers and polyurethane elastomers are outstanding materials with a lot of applications. Hence, they received a widespread attention since they have been discovered [1-5]. Most of these researches aimed the improvement of elastic properties and the increase of Young s modulus for applications such as rigid materials or soft structural materials. Few of them combined high elastic properties, high elongation at break and a low Young s modulus. [Pg.217]

It is an ideal structural material. It has about same Young s modulus as steel ( 2x lO MPa). [Pg.379]

A composite material consists of flat, thin metal plates of uniform thickness glued one to another with a thin, epoxy-resin layer (also of uniform thickness) to form a multi-decker-sandwich structure. Young s modulus of the metal is Ej, that of the epoxy resin is E2 (where E2 < Ej) and the volume fraction of metal is Vj. Find the ratio of the maximum composite modulus to the minimum composite modulus in terms of Ej, E2 and V. Which value of gives the largest ratio ... [Pg.278]

First, we must realize that many variables exist in any structural design. We can make a list of structural variables such as sizes, lengths of objects, materials, laminae orientations, and so on. those variables all have influence just as column length, moment of inertia, and Young s modulus influence column-buckling loads. The complete list of design variables will be called the vector Xj, and that vector will have N components. That list constitutes the definition of the structural configuration. [Pg.426]

The actual experimental moduli of the polymer materials are usually about only % of their theoretical values [1], while the calculated theoretical moduli of many polymer materials are comparable to that of metal or fiber reinforced composites, for instance, the crystalline polyethylene (PE) and polyvinyl alcohol have their calculated Young s moduli in the range of 200-300 GPa, surpassing the normal steel modulus of 200 GPa. This has been attributed to the limitations of the folded-chain structures, the disordered alignment of molecular chains, and other defects existing in crystalline polymers under normal processing conditions. [Pg.295]

Cardioembolism Cardioembolism accounts for approximately 30% of all stroke and 25-30% of strokes in the young (age <45 years)." AF accounts for a large proportion of these strokes (15-25%). Symptoms may be suggestive, but they are not diagnostic. Repetitive, stereotyped, transient ischemic attacks (TIAs) are unusual in embolic stroke. The classic presentation for cardioembolism is the sudden onset of maximal symptoms. The size of the embolic material determines, in part, the course of the embolic material. Small emboli can cause retinal ischemic or lacunar symptoms. Posterior cerebral artery territory infarcts, in particular, are often due to cardiac embolism. This predilection is not completely consistent across the various cardiac structural abnormalities that predispose to stroke, and may be due to patterns of blood flow associated with specific cardiac pathologies. [Pg.203]

Whereas the tensile strength was not a sensitive function of the monomer structure, the tensile modulus (Young s Modulus) was clearly related to the monomer structure. This is expected since the tensile modulus is a measure of the polymer s resistance to deformation and is related to the "stiffness" of a polymeric material. The highest tensile modulus (22,000 kg/cm2,2.2 GPa) was measured for poly(BPA iminocarbonate). Replacement of BPA by Dat-Tyr-Hex reduced the tensile modulus significantly. This observation can possibly be attributed to the presence of the long hexyl ester pendent chain in Dat-Tyr-Hex. Generally, the polyiminocarbonates were somewhat "stiffer" than the corresponding polycarbonates. Thus, the tensile moduli of poly(Dat-Tyr-Hex iminocarbonate) and poly(Dat-Tyr-Hex carbonate) were 16,300 kg/cm2 (1.6 GPa) and 13,900 kg/cm2 (1.3 GPa) respectively. [Pg.165]

The melting process and the differentiation of the Earth s matter according to its density caused the lighter crust minerals to migrate to the outer layers of the still young Earth, whose surface temperature at that time was such that it was covered by a sea of melted rock (Wills and Bada, 2000). This separation of materials led to the layer structure of the Earth ... [Pg.28]

Laboratory data from two groups (see Sect. 3.2.4) indicate that chiral amino acid structures can be formed in simulations of the conditions present in interstellar space. The experimental results support the assumption that important asymmetrical reactions could have taken place on interstellar ice particles irradiated with circularly polarised UV light. The question as to whether such material was ever transported to the young Earth remains open. But the Rosetta mission may provide important answers on the problem of asymmetric syntheses of biomolecules under cosmic conditions (Meierhenrich and Thiemann, 2004). [Pg.253]

Young, R.A. and Mackie P.E.(1980) Crystallography of human tooth enamel — initial structure refinement. Materials Research Bulletin, 15, 17—29. [Pg.394]


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See also in sourсe #XX -- [ Pg.123 ]




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