Scaling approach to conical indentation in elastic-plastic solids with work hardening

We derive, using dimensional analysis and finite element calculations, several scaling relationships for conical indentation in elastic-plastic solids with work hardening. Using these scaling relationships, we examine the relationships between hardness, contact area, initial unloading slope, and mechanical properties of solids. The scaling relationships also provide new insights into the shape of indentation curves and form the basis for understanding indentation measurements, including nano- and micro-indentation techniques. They may also be helpful as a guide to numerical and finite element calculations of indentation problems.

Research on the Temperature Field in Laser Hardening

Temperature field in the laser hardening process was numerically simulated by MSC.Marc software. The influence of energy density on laser hardening effect is analyzed. Simulation result is verified through the thermocouple temperature transducer measuring the specimen surface temperature under the laser irradiation. Experimental curves of temperature versus time are in agreement with simulation results. The simulation results can be regarded as a basis for choosing laser technological parameters.

Numerical Investigation on Laser Transformation Hardening with Different Temporal Pulse Shapes

A 3-D numerical model for pulsed laser transformation hardening (LTH) is developed using the finite element method. In this model, laser spatial and temporal intensity distribution, temperature-dependent thermophysical properties of material, and multi-phase transformations are considered. The influence of laser temporal pulse shape on connectivity of hardened zone, maximum surface temperature of material and hardening depth is numerically investigated at different pulse energy levels. Results indicate that these hardening parameters are strongly dependent on the temporal pulse shape. For the rectangular temporal pulse shape, the temperature field obtained from this model is in excellent agreement with analytical solution, and the predicted hardening depth is favorably compared with experimental one. It should be pointed out that appropriate temporal pulse shape should be selected according to pulse energy level in order to achieve desirable hardening quality under certain laser spatial intensity distribution.

Restricciones, privilegios y violencias : algunos aspectos sobre los mudéjares hispánicos (ss. XII-XV)

En el presente trabajo nos proponemos abordar algunos aspectos relacionados con las restricciones, los privilegios y la violencia, que se implementaron sobre los mudéjares de Castilla, Aragón y Valencia. En relación con los primeros, daremos cuenta del endurecimiento legal –real y eclesiástico– que se desplegó hacia los moros hispánicos y que regló casi todos los aspectos del vivir cotidiano y de sus prácticas religiosas. Sin embargo, los mudéjares y sus aljamas en algún área en particular, fueron sujetos de privilegios reales. Es por esto que analizaremos restricciones y privilegios como dos caras de un mismo proceso que se desplegó durante el tránsito de la baja edad media. Finalmente, indagaremos sobre los episodios de violencia hacia los mudéjares contrastando particularidades regionales, para conectar estos sucesos con la segregación y la restricción.

Work Softening And Annealing Hardening Of Deformed Nanocrystalline Nickel

We reported that work softening takes place during room-temperature rolling of nanocrystalline Ni at an equivalent strain of around 0.30. The work softening corresponds to a strain-induced phase transformation from a face-centered cubic (fcc) to a body-centered cubic (bcc) lattice. The hardness decreases with increasing volume fraction of the bcc phase. When the deformed samples are annealed at 423 K, a hardening of the samples takes place. This hardening by annealing can be attributed to a variety of factors including the recovery transformation from the bcc to the fcc phase, grain boundary relaxation, and retardation of dislocation gliding by microtwins.

Recently discovered Iron Age lion figurines from Jerusalem

Abstract: More than 500 Iron Age figurines were discovered in the 2005–2010 Western Wall Plaza excavations in Jerusalem.1 The excavations revealed a large building, probably of the four-room type. Many figurines were discovered in this building, others in fills below and above it, dating in general to the eighth-sixth centuries BCE. Here we focus on two heads most likely depicting lions, one of them exceptional—holding another animal in its mouth. We discuss the identification of these figurines as lions, the lion motif in a variety of media in the Southern Levant, and finally recent theories concerning lions in the Hebrew Bible and their relation to Yahweh. We suggest that the two Western Wall Plaza figurines represent lions as wild animals, in similarity to other figurines of wild animals made on occasion by Judean coroplasts.

Local exchange in the southern levant during the early bronze age: a political economy viewpoint

Trade and relations between the southern Levant and other regions of the Near East (mainly Egypt) during the Early Bronze Age (ca. 3,600–2,300 BC) have been the subject of many studies. Research concerning the exchange of local commodities was almost ignored or was discussed in parochial studies, focusing on specific archaeological finds. It is the intention of this paper to present the results of recent research of the exchange of commodities provided by archaeological data from excavations in the Southern Levant with regard to economic theories on the exchange-value of goods and exchange networks. Conclusions regarding the type of society and the forms of government in the Southern Levant during the Early Bronze Age are also presented.

The open parliament in the age of the internet : can the people now collaborate with legislatures in lawmaking?

This work seeks to address those questions and evaluate other international experiences and experiments designed to achieve the same ends. The book is based on a study of two particular cases where parliamentary bodies designed and implemented participatory digital processes, namely, the e-Democracy Program developed by the Brazilian House of Representatives, and the Virtual Senator Program developed by the Chilean Senate. The text unfolds in the form of a systematic analysis of institutional aspects embracing political and organizational elements as well as the social aspects associated to the application of digital democracy in parliaments. The investigation shows that at the stage they found themselves in 2010 those projects had only brought in very incipient results in regard to the aspects of enhancing representativity in decision making processes, aggregating collective intelligence to the legislative process or transparency to parliamentary performances, even though all of those are precious components of any democracy that deems itself to be participatory and deliberative. Nevertheless, such experiences have had the merit of contributing towards the gradual construction of more effective participatory mechanisms, complementary to the political representation system in place.

A new expression of hardening coefficients for fcc-crystal and calibration of the material constants

In order to describe the effect of latent hardening on the macro-plastic behavior of foc-crystal, a new expression for hardening coefficient is proposed in which there are 12 material constants, each having clear physical meaning. And a method of material constant calibration is suggested and used to determine the material constants of copper and aluminum crystal. The simulated load-elongation curves along various crystallographic orientations are comparable with the experimental ones.

Higher-order analysis of crack-tip fields in power-law hardening materials

In this paper, we present an exact higher-order asymptotic analysis on the near-crack-tip fields in elastic-plastic materials under plane strain, Mode I. A four- or five-term asymptotic series of the solutions is derived. It is found that when 1.6 < n less-than-or-equal-to 2.8 (here, n is the hardening exponent), the elastic effect enters the third-order stress field; but when 2.8< n less-than-or-equal-to 3.7 this effect turns to enter the fourth-order field, with the fifth-order field independent. Moreover, if n>3.7, the elasticity only affects the fields whose order is higher than 4. In this case, the fourth-order field remains independent. Our investigation also shows that as long as n is larger than 1.6, the third-order field is always not independent, whose amplitude coefficient K3 depends either on K1 or on both K1 and K2 (K1 and K2 arc the amplitude coefficients of the first- and second-order fields, respectively). Firmly, good agreement is found between our results and O'Dowd and Shih's numerical ones[8] by comparison.

Higher-order analysis of crack tip fields in elastic power-law hardening materials

A HIGHER-ORDER asymptotic analysis of a stationary crack in an elastic power-law hardening material has been carried out for plane strain, Mode 1. The extent to which elasticity affects the near-tip fields is determined by the strain hardening exponent n. Five terms in the asymptotic series for the stresses have been derived for n = 3. However, only three amplitudes can be independently prescribed. These are K1, K2 and K5 corresponding to amplitudes of the first-, second- and fifth-order terms. Four terms in the asymptotic series have been obtained for n = 5, 7 and 10; in these cases, the independent amplitudes are K1, K2 and K4. It is found that appropriate choices of K2 and K4 can reproduce near-tip fields representative of a broad range of crack tip constraints in moderate and low hardening materials. Indeed, fields characterized by distinctly different stress triaxiality levels (established by finite element analysis) have been matched by the asymptotic series. The zone of dominance of the asymptotic series extends over distances of about 10 crack openings ahead of the crack tip encompassing length scales that are microstructurally significant. Furthermore, the higher-order terms collectively describe a spatially uniform hydrostatic stress field (of adjustable magnitude) ahead of the crack. Our results lend support to a suggestion that J and a measure of near-tip stress triaxiality can describe the full range of near-tip states.