Solid behavior of anisotropic rigid frictionless bead assemblies

We investigate the structure and mechanical behavior of assemblies of frictionless, nearly rigid equal-sized beads, in the quasistatic limit, by numerical simulation. Three different loading paths are explored: triaxial compression, triaxial extension and simple shear. Generalizing recent results [1], we show that the material, despite rather strong finite sample size effects, is able to sustain a finite deviator stress in the macroscopic limit, along all three paths, without dilatancy. The shape of the yield surface is adequately described by a Lade-Duncan (rather than Mohr-Coulomb) criterion. While scalar state variables keep the same values as in isotropic systems, fabric and force anisotropies are each characterized by one parameter and are in one-to-one correspondence with principal stress ratio along all three loading paths.The anisotropy of the pair correlation function extends to a distance between bead surfaces on the order of 10% of the diameter. The tensor of elastic moduli is shown to possess a nearly singular, uniaxial structure related to stress anisotropy. Possible stress-strain relations in monotonic loading paths are also discussed

Numerical simulation techniques to study the structural response of the human chest following median sternotomy

Numerical simulation techniques to study the structural response of the human chest following median sternotom

Sistemas integrados de produção no Brasil: situação atual, causas e perspectivas

Este artigo apresenta e analisa os resultados de uma pesquisa com 260 empresas de manufatura de 10 estados brasileiros. Ele descreve sua metodologia e explora as relações entre suas características - posição estratégica, tamanho, natureza dos processos de produção, tipo de indústria e região - e seu padrão de automação. Discute tendências e necessidades para um futuro próximo e apresenta alguns comentários sobre o conteúdo da tecnologia adotada pelas empresas. Além disso, faz algumas considerações a respeito dos processos de modernização industrial.<br>This paper presents and analyzes the results of a survey of 260 manufacturing firms in 10 states in Brazil. It describes its metodology and explores the relationships between firms's characteristics -strategic positioning, size, nature of production process, industry and region - and their automation pattern. It discusses trends and needs for the near-future and offers some remarks about the content of the tecnology adopted by the firms. It also speculates about the nature of the industry's modernization process