Asymptotic solution of mode-iii crack in damaged softening materials

In this paper, a constitutive model of elasticity coupled with damage suggested by Lemaitre et al, [1] is used. The macroscopic stress-strain response of the model includes two stages: strain hardening and strain softening. The basic equation is derived for the anti-plane shear problem. Several lowest order asymptotic solutions are obtained, and assembled for the crack-tip fields.

Inhomogeneous behavior of antiplane shear crack in softening material with local unloading

Examined in this work is the anti-plane stress and strain near a crack in a material that softens beyond the elastic peak and unloads on a linear path through the initial state. The discontinuity in the constitutive relation is carried into the analysis such that one portion of the local solution is elliptic in character and the other hyperbolic. Material elements in one region may cross over to another as the loading is increased. Local unloading can thus prevail. Presented are the inhomogeneous character of the asymptotic stress and strain in the elliptic and hyperbolic region, in addition to the region in which the material elements had experienced unloading. No one single stress or strain coefficient would be adequate for describing crack instability.

Un método para el taladro de aluminio que facilita la unión por remaches de los componentes aeronáuticos

189 p. : il. col.

祖国力学事业辛勤的耕耘者——恭贺挚友伟长先生九秩华诞

<正> 今年正值我的老朋友钱伟长先生九十华诞,我愿在此向他表示最诚挚的祝贺,祝愿他健康长寿、老当益壮、诸事顺遂! 我与伟长先生的相识、相知可追溯到半个多世纪之前. 1946年初我赴美留学, 2月间到了加州理工学院的喷气推进研究室(JPL),那时在Th.von Karman教授周围可谓人才济济,特别是集中着几位出类拔萃的中国青年学者:钱学森、钱伟长、郭永怀、林家翘等等,我很快就与他们熟悉了.青年钱伟长给我留下了

Alejandra Pizarnik: "Si no me escribo soy una ausencia"

[ES] Este trabajo propone una lectura de los seis primeros cuadernos del diario que Alejandra Pizarnik escribió a lo largo de toda su vida, desde los 18 años y hasta que murió a la edad de 36. El análisis de estos cuadernos, escritos entre 1954 y 1958, nos permite recorrer el itinerario que Alejandra Pizarnik realiza por la cuestión genérica, la cuestión nacional y la cuestión sexual. Desde su experiencia en cuanto sujeto, la escritura registra esta primera fase en la construcción del yo que Pizarnik desea para su diario. Esta fase, que se puede denominar etapa-derribo, está dominada por el desafío a las ideas del discurso hegemónico. Una vez haya resuelto este escollo en la construcción del yo de su diario, la escritura de Pizarnik no volverá sobre estos temas. Sin embargo, la búsqueda el “verdadero” yo se registra como proceso en el que a un movimiento de construcción del yo, le sigue un movimiento de destrucción de lo que las palabras han conformado, en secuencias en las que la apelación a la mentira de lo escrito o la desconfi anza en la capacidad del lenguaje para expresarlo, son la pauta de dicha escritura.

Atraso e innovación tecnológicos en la siderurgia guipuzcoana durante el antiguo régimen

[ES]Durante décadas la historiografía ha considerado que la siderurgia vasca, y dentro de ella la guipuzcoana, sufrió un claro «atraso tecnológico», anclada en los métodos directos, en un momento de expansión mundial de los sistemas indirectos. El presente artículo hace un análisis diacrónico de la evolución tecnológica de la mencionada actividad entre los siglos XIII y XIX, centrando su discurso, tanto en los intentos e iniciativas innovadoras, tratando de desentrañar las verdaderas razones que llevaron dichos proyectos innovadores al éxito o al fracaso, como en las continuidades. En definitiva, se trata de matizar y relativizar el mencionado concepto.

第四届世界生物力学大会简介

"第四届世界生物力学大会"(4~(th)World Congress on Biomechanics)于2002年8月3~11日在加拿大卡尔加里(Calgary,Canada)召开．会议主办单位为卡尔加里大学，参会人数约1 600人．参加会议的主要国家包括：美、英、德、日、加、意、法、中国和中国香港等50余国家和地区．会议交流的论文篇数约为1680篇(含口头报告及墙展)．中国中科院力学所、中日友好医院、四川大学、重庆大学等6位学者参加了本次会议．所发表的工作分别涉及细胞与分子生物力学、假肢生物力学、白细胞力学-生物学耦合、血流动力学等方面，其研究工作在整体上符合当前本领域的发展方向，有的工作具有国际竞争性，会议的反响是肯定的．作者在"分子与细胞生物力学"(Molecular and Cellular Biomechanics)分会上做了口头报告和墙报展讲．

Serrated Plastic Flow During Nanoindentation in Nd-Based Bulk Metallic Glasses

The microstructure of Nd_{60}Al_{10}Ni_{10}Cu_{20-x}Fex (x = 0, 5, 7, 10, 15, 20) alloys can change from homogeneous phase to a composite structure consisting of amorphous phase plus clusters or nanocrystals by adjusting the Fe content. The effect of microstructure on the plastic deformation behavior in this alloy system is studied by using nanoindentation. The alloys with homogeneous amorphous structure exhibit pronounced flow serrations during the loading process of nanoindentation. The addition of Fe changes the plastic deformation behavior remarkablely. No flow serration is observed in the alloys with high Fe content for the indentation depth of 500 nm. The mechanism for the change of plastic serrated flow behavior is discussed.

Determination of plastic properties by instrumented spherical indentation: Expanding cavity model and similarity solution approach

The present paper aims to develop a robust spherical indentation-based method to extract material plastic properties. For this purpose, a new consideration of-piling-up effect is incorporated into the expanding cavity model; an extensive numerical study on the similarity Solution has also been performed. As a consequence, two semi-theoretical relations between the indentation response and material plastic properties are derived, with which plastic properties of materials can be identified from a single instrumented spherical indentation curve, the advantage being that this approach no longer needs estimations of contact radius with given elastic modulus. Moreover, the inconvenience in using multiple indenters with different tip angles can be avoided. Comprehensive sensitivity analyses show that the present algorithm is reliable. Also, by experimental verification performed oil three typical materials, good agreement of the material properties between those obtained from the reverse algorithm and experimental data is obtained.

CHARACTERIZATION OF SHEAR BANDS IN TWO BULK METALLIC GLASSES WITH DIFFERENT INHERENT PLASTICITY

Shear banding characterization of Zr64.13Cu15.75Ni10.12Al10 and Zr65Cu15Ni10Al10 bulk metallic glasses (BMGs) with significant difference in inherent plasticity and quite similar chemical composition was studied by depth sensitive macroindentaion tests with conical indenter. Well-developed shear band pattern can be found for both BMGs after indentation. Distinct difference in the shear band spacing, scale of plastic deformation region and the shear band branching in the two BMGs account for the different plasticity.