Measurements of anisotropic elastic constants of type 308 stainless-steel electroslag welds

In austenitic-stainless-steel weld metal, mechanical anisotropy is caused by preferred local orientation of elongated subgrains and preferred crystallographic orientation. Ultrasonic and static tensile-test methods used to determine elastic stiffness and compliance matrices, respectively, demonstrated that orthotropic symmetry exists. Inversion of this compliance matrix gave a stiffness matrix which showed general agreement between the two methods. It is suggested that the data can be used directly in finite-element analyses of weldments containing Type 308 stainless steel.     

一种舰船变形测量方法的研究与应用

以舰船船体结构、惯性导航系统、被试导航设备以及天文经纬仪为物理对象，提出了一套利用光学系统原理和计算机图像处理技术对联合基座进行水平变形测量的方法，解决了各设备因安装位置的不同所造成的安装基座间产生的水平变形量问题。     

Residual stresses and warp generated by one-sided quench of an epoxy-resin beam

This paper discusses the warp and accompanying residual stress in a rectangular epoxy beam produced by water cooling its lower surface. First, the theoretical values of this warp and residual stress are obtained by the linear-viscoelastic theory. The specimen is then subjected to quenching. The variations in the warp are observed. After quenching, the residual stress is measured by a layer-removal method. The experimental and theoretical results are then compared and discussed.     

Stability of a cylindrical shell under programmed variation of an axial compressive force under creep conditions

Journal of Applied Mechanics and Technical Physics - The stability of cylindrical shells with initial deflection is examined under creep with a programmed load. Data are presented from an...     

Fatigue-damage evaluation for mild steel incorporating mean stress and overload effects

Successful estimation of the service life of a structure or component which is subjected to a complex history of loading, depends on a suitable cumulative-damage summation technique. A general technique must be capable of predicting the effects on fatigue life of geometry, mean stress or strain, occasional overloads or overstrains, frequency of cycling and environment. As a contribution towards the general solution, this paper describes the utilization of a fatigue-damage summation method which incorporates two of these variables, mean stress and overloads. The method is tested for complex load histories in mild-steel specimens in the intermediate to long-life range. A four-part constant-stress-amplitude testing program was carried out consisting of: (a) tests with a constant mean stress, (b) tests on prestrained specimens, (c) tests with a mean stress applied in one block of cycles, and (d) tests with a mean stress applied in frequent regularly spaced short blocks. The constant-mean-stress results, which include several values of mean stress both tensile and compressive, are reduced to a single curve on a stress-life plot with either of two simple parameters (from Morrow and Smith, et al.) as ordinate. The prestrained specimen tests result in another curve lower than the first, showing the reduction in life due to the few initial cycles of high strain. These two effects are then incorporated into a cumulative-damage summation technique which is based on the well-known Miner's rule. The two curves on the stress-life plot are the foundation for the subsequent summations. The technique assumes that the first application of an overload causing appreciable plastic straining reduces the remaining fatigue life. A significant point is that this assumption apparently holds for both tensile and compressive overloads. The accuracy of this technique is demonstrated for a wide range of stress conditions and loading histories.     

Cyclic-deformation behavior of notched mild-steel plates in plane stress

Notched rectangular SAE 1015 mild-steel plates were subjected to controlled cyclic nominal stresses or strains in a closed-loop servo-controlled fatigue-testing machine. Resistance strain gages were used to measure strains at the notch roots. These strains showed that large mean strains and strain ranges prevailed at these notches, though nominal strains were fully reversed and small. Inelastic stress- and strain-concentration factors calculated at various cycles were used to check the accuracy of the Neuber relation between these concentration factors and elastic stress-concentration factor. Limitations of this relation and characteristic notch-strain behavior mentioned above are discussed with reference to the peculiarities of the stress-strain relationships of this material.     

Dynamic-stress concentration using photoelasticity and a laser light source

Since experimental techniques using dynamic photoelasticity are, in general, limited by suitably intense monochromatic light sources, it was of primary importance to describe a ruby-laser system which would completely remove this particular aspect of the problem. Modulation of the system, in this case by a Kerr cell, provides the necessary control of the light output such that a complete series of results can be obtained by putting together the results of many individual tests recorded on a conventional still camera. In this case, the dynamic-stress-concentration factor in a strut with a symmetrically located circular discontinuity was determined to establish definitely the potential of the system.     

Heat transfer in condensation on a vertical tube in a granular bed

S. S. Kutateladze Institute of Heat Physics, Siberian Branch of the Russian Academy of Sciences. Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 36, No. 6, pp. 102–107, November–December, 1995.     

Rheological properties of wheat flour doughs

Summary A comparative study was made of the large deformation and rupture properties of doughs from a medium strength and a weak wheat flour. Experiments were made by stretching, at a uniform rate, dough rings immersed in a liquid of matching density to prevent the rings from deforming under their own weight. Data were obtained on doughs differing in water content at temperatures from 5 to 45 °C and extension rates from 0.132 to 52.6 inches per minute.Essentially, the tensile properties of each dough could be represented by four characteristic functions, each dependent on only one of the variables: strain, time, temperature, and water content. The strain function (), equaled (In)/, where is the extension ratio, for extensions up to about 90% and, in some instances, up to nearly 200%. Thus, over extended ranges of strain, isochronal stress-strain data (representing comparable states of stress relaxation) gave a direct proportionality between true stress and theHencky strain, _H=In; the proportionality constant is the constant strain rate modulus,F (t^*), evaluated at the (isochronal) timet ^*. The modulusF(t,T,W — a function of timet, temperatureT, and water absorptionW-equals (T/T ₀)F (t ^*,T ₀,W ₀) (t/t ^* a _T a _W)ⁿ, wheren is a negative constant characteristic of the flour,F (t ^*,T ₀,W ₀) is the modulus at timet ^* at the reference temperatureT ₀ for a dough having the reference water absorptionW ₀;a _T anda _W are shift factors that account for the change of relaxation times with temperature and water content. The factor ay obeyed theArrhenius equation and gave activation energies of about 7.7 and 22.8 kcal for doughs from the medium strength and weak flour, respectively. Rupture data obtained at different temperatures and extension rates were superposed by usinga _T data and also were represented by failure envelopes. The shift factora _W appears to depend somewhat on temperature, especially for the weaker flour.Differences in the rheological behavior of doughs from the two flours were evident in: (1) the range over which the isochronal stress-strain behavior could be linearized; (2) the magnitude of the characteristic exponentn; (3) the magnitude and the temperature dependence of the moduli; (4) the activation energies; (5) the effect of temperature ona _W; and (6) several characterizing plots prepared to represent rupture data.

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Zusammenfassung Es wurde eine Vergleichsuntersuchung betreffend große Verformungen und Brucheigenschaften von Teigen aus zwei Weizenmehltypen durchgeführt. Die Versuche wurden in der Weise ausgeführt, daß man Teigringe, die in eine Flüssigkeit von entsprechender Dichte eingetaucht waren, um zu verhindern, daß sich die Ringe unter der Wirkung ihres eigenen Gewichtes verformten, mit gleichbleibender Geschwindigkeit streckte. Es wurden Werte für verschiedene Teige ermittelt, die sich durch ihren Wassergehalt unterschieden, und zwar bei Temperaturen von 5–45 °C und Dehnungsgeschwindigkeiten von 0,132–52,6 Zoll pro Minute.Die Zugeigenschaften eines jeden Teiges konnten im wesentlichen durch vier charakteristische Funktionen dargestellt werden, von denen jede lediglich von einer der Veränderlichen: Verformung, Zeit, Temperatur und Wassergehalt abhing. Die Verformungsfunktion () war gleich (In)/, worin das Dehnungsverhältnis bedeutet, und zwar für Dehnungen bis zu ungefähr 90%, in einigen Fällen sogar bis zu fast 200%. Somit ergab sich über einem ausgedehnten Verformungsbereich für die isochronen Kraft-Dehnungs-Werte (die vergleichbare Zustände der Spannungsrelaxation darstellen) eine direkte Proportionalität zwischen wahrer Spannung undHencky- Verformung, _H=In; die Proportionalitätskonstante ist der ModulF (t^*), genommen bei konstanter Verformungsgeschwindigkeit und der (isochronen) Zeit t^*. Der ModulF (t, T, W)eine Funktion der Zeitt, der TemperaturT und der WasserabsorptionW — läßt sich darstellen durch (T/T ₀)F (t ^*,T ₀,W ₀ ) (t/t ^* a _T a _W)ⁿ, worinn eine für das Mehl charakteristische negative Konstante undF (t ^*,T ₀,W ₀) der Modul zur Zeitt ^* bei der BezugstemperaturT ₀ ist für einen Teig, der die Bezugs-WasserabsorptionW ₀ hat;a _T unda _W sind Verschiebungsfaktoren, die der Veränderung der Relaxationszeiten mit der Temperatur und dem Wassergehalt Rechnung tragen. Der Faktor ay gehorcht derArrhenius-Gleichung und ergibt Aktivierungsenergien von ungefähr 7,7 bzw. 22,8 kcal für die Teige der beiden Mehltypen. Bruchwerte, die bei verschiedenen Temperaturen und verschiedenen Dehnungsgeschwindigkeiten erhalten wurden, ließen sich durch Verwendung vona _T-Daten überlagern und durch eine Brucheinhüllende (failure envelope) darstellen. Der Verschiebungsfaktora _W scheint etwas von der Temperatur abzuhängen, und zwar besonders bei dem schwächeren Mehl.Unterschiede im rheologischen Verhalten von Teigen aus den beiden Mehlsorten bestanden offensichtlich in Bezug auf: (1) den Bereich, über den das isochrone Kraft-Dehnungs-Verhalten linearisiert werden konnte, (2) die Größe des charakteristischen Exponentenn, (3) die Größe und die Temperaturabhängigkeit der Moduln, (4) die Aktivierungsenergien, (5) die Wirkung der Temperatur aufa _W und (6) einige graphische Darstellungen zur Charakterisierung der Bruchwerte.

     

Group properties of the equations of adiabatic motion of a medium in relativistic hydrodynamics

A group classification is presented and the complete set of invariant solutions is found for the equations of adiabatic motion of a medium in relativistic hydrodynamics.