Stress tensile, definition

Definitions of the commonly measured tensile properties are as follows Unear density (tex) is the weight in grams of 1000 m of yam. Tenacity is the tensile stress at break and is expressed in force-per-unit linear density of unstrained specimen, N /tex. Knot tenacity is the tensile stress required to mpture a single strand of yam with an overhand knot tied in the segment of sample between the testing clamps. It is expressed as force-per-unit linear density and is an approximate measure of the britdeness of the yam. Toop tenacity is the tensile stress required to mpture yam when one strand of yam is looped through... 

The sign associated with the pressure is opposite to that associated with the normal viscous stress. The usual sign convention assumes that a tensile stress is the positive normal stress so that the pressure, which by definition has compressive normal stress, has a negative sign. 

Definitive studies of composite material tensile strength from a micromechanics viewpoint simply do not exist. Obviously, much work remains in this area before composite materials can be accurately designed, i.e., constituents chosen and proportioned to resist a specified tensile stress. 

A substantial number of definitions in the terminology section are either of physical quantities or are expressed mathematically. In such cases, there are recommended symbols for the quantities and, when appropriate, corresponding SI units. Other terms have eommon abbreviations. The following format is used to indicate these essential eharaeteristics name of term (abbreviation), symbol, SI unit unit. Typical examples are tensile stress, interpenetrating polymer network (IPN). If there are any, alternative names or synonyms follow on the next line, and the definition on the sueeeeding lines. 

In performing such experiments on isotropic materials, one is accustomed to express the elastic stiffness parameters in the experimentally more readily accessible technical parameters E (Young s modulus) and v (Poisson ratio). The relative change in length, in the direction of the tensile stress a is, by definition, given by (Al/t)i — a/E, whereas v = (Af/ )x/( A / )u. For several magnetostrictive films and substrates, E and v values are listed in table 1. Some useful relations are ... 

Tyres are very definitely fatigued during use and, as mentioned for fabric/rubber adhesion above, it is very important to carry out dynamic tests to assess bond efficiency. Methods have not apparently been standardised but a variety of procedures have been reported71 79 Some workers have used the same or a similar test piece as in static tests and applied a cyclic tensile stress or strain, whilst others have used some form of fatigue tester operating in compression/shear to repeatedly stress or strain cord/rubber composite, or even to flex samples in the form of a belt. Khromov and Lazareva80 describe a method using test pieces cut from tyres. 

The detailed work of Bernd (ref. 15-17) and other investigators has also shown that the tensile strength of water is set by the gas nuclei (i.e., microbubbles) present in the water. (Accordingly, the earlier-mentioned definition of the tensile strength of a liquid can be restated as the minimum tensile stress at which the gas nuclei in the liquid start to explode . This property is also often referred to as the cavitation susceptibility (ref. 57).) Using specially constructed sonar transducers, the behavior of gas nuclei was followed by Bernd by measuring tensile strength. Surface... 

In the above considerations, a sinusoidal shear strain is applied to the sample. It should be clear that a sinusoidal shear stress could also be applied resulting in corresponding compliance functions J and J". The former results from the deformation in phase with the stress, while the latter corresponds to the out-of-phase deformation. The value of tan 5 remains the same, as can be seen from the curves in Figure 2-13, where we can easily imagine the stress as the applied variable and strain as the measured variable. Tensile stress is equally applicable and definitions of E (co), E" (o), D"(co), D co), etc. are completely analogous to the derived shear parameters. At a given frequency, the value of tan 8 is always the same for any of these quantities, i.e., tan 8 = E"/E = D"/D . 

Young s equation is deceptively simple actually, there are present conceptual and experimental difficulties and Equation 1 has been the source of many arguments. In the definition of and ygv > neither of which we can conveniently and reliably measure, there is the difficulty that any tensile stresses existing in the surface of a solid would rarely be a system in equilibrium. Solids are rare whose surfaces are free of stresses which have penetrated from below the surface layer. Lester [77] has recently given a sophisticated treatment of Young s equation and has shown that it is correct so long as the drop of liquid rests on a solid which is not too deformable. 

FYom the multitude of intricate corrosion processes in the presence of mechanical action (friction, erosion, vibration, cavitation, fretting and so on) it is justified to touch upon corrosion types joined under a single failure mode induced by mechanical stresses. These are the stresses that govern the corrosion wear rate of metals during friction. Such processes are usually called corrosion stress-induced cracking in the case that the mechanical action is effective only in one definite direction, or otherwise termed corrosion fatigue in the case that compressive and tensile stresses alternate within cycles. In spite of the differences between the appearance of these corrosion types, they have much in common, e.g. fundamental mechanisms, the causes, and they overlap to a certain degree [19]. 

If both sides are divided by the original cross-sectional areav4o = Vo /lo, then, with the definition of the tensile stress on = F jAo, the gas constant R = ENl,... 

An important requirement for any implant material is how long it will last. Because of the nature of failure of ceramic components it is not possible to provide a specific and definite lifetime for each individual implant. Rather we have to express failme in terms of probabilities. Figure 16.27 is an applied stress versus probability of time to failure (SPT) diagram for medical grade alumina. It shows that for a 30-year survival period with failure of no more than 1 in 100 components the maximum tensile stress that can be applied is limited to <200MPa. If stresses of... 

Now, according to Trouton s definition of the elongational viscosity A, a liquid instantaneously elongating at de,/dr generates a tensile stress o, (=F/A),... 

A more scientific definition is given by Veis [423] The gelatins are a class of proteinaceous substance that have no existence in nature, but are derived from the parent protein collagen, by any one of a number of procedures involving the destruction of the secondary structure of the collagen and, in most cases, some aspects of the primary and tertiary structures. Collagen is the principle proteinaceous component of the white fibrous connective tissues, which serve as the chief, tensile stress-bearing elements for all vertebrates, whereas related protons are found in any of the lower phyla . 

The equivalent (uniaxial) stress is the uniaxial tensile stress which would have the same damaging action as an applied multi-axial stress state. The proper definition of the equivalent stress depends on the type of the fracture causing flaws, and how such flaws act as cracks (though this remains a matter of some debate). The definition also depends on the fracture criterion for multi-axial stress states, and this should also take into account the action of compressive stresses. Precise information on real flaw distributions and multi-axial strength data are rarely available, and the large scatter of strength values makes unambiguous interpretation of these data difficult. 

The fiber-reinforced composite materials are characterized by an anisotropic behavior. When they undergo tensile stress towards a definite direction, for example, the fiber direction, they show a linear reaction up to the breaking strength, whose characteristic value is The maximum factored deformation allowed for FRP reinforcement is ... 

From the ASTM definition, stress corrosion cracking is the simultaneous action of a corrosive environment and a sustained tensile stress promoting rupture" [54]. Both SCC and deallo)dng often occur in the same environment. By the 1940s, deaUoying was considered to be involved in the initiation of SCC [57]. 

Following the above analytical conclusions, because the maximum tensile stress occurs at the periphery of the indentation, circle BB, it would be expected that at some critical load a crack would nucleate and propagate around the circumference BB. On a surface of glass or another amorphous material a ring crack is observed, but on highly anisotropic crystalline ceramics a less well traced crack is produced as the ring has a definite... 

Fracture mechanics considerations, summarized for polymers by Kausch [40,41], permit determination of the effect of defects on the fracture stress, or tensile strength, of bulk polymers and polymer fibers. It is important that such detailed study be performed on the original or primary fracture surfaces, which are the only surfaces which relate to the tensile stress. This is generally done by examining both failure surfaces to ensure that they are a matched pair. An example of matched, primary fracture surfaces was shown earlier (Fig. 4.29). In that case, a definite defect site was observed in the brittle fracture surface. Such assessment provides the structure-property information needed to modify the process and produce fibers with higher strengths. 

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