نتایج جستجو برای: modified strain gradient

تعداد نتایج: 583107  

Journal: :European Journal of Mechanics A-solids 2023

A new simulation strategy to model hydrogen embrittlement based on a multi-field finite element using displacements, pressure, volume variation, nonlocal damage variables and lattice concentration as unknowns is proposed. The material described modified GTN model, which includes the description of enhanced decohesion (HEDE). problem solved fully implicit formulation. Numerical problems related ...

2012
K. L. Nielsen J. W. Hutchinson

Steady state crack propagation produce substantial plastic strain gradients near the tip, which are accompanied by a high density of geometrically necessary dislocations and additional local strain hardening. Here, the objective is to study these gradient effects on Mode I toughness of a homogeneous rate-sensitive metal, using a higher order plasticity theory. Throughout, emphasis is on the tou...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه گیلان - دانشکده کشاورزی 1391

به منظور بررسی اثر باکتری های محرک رشد در تلفیق با کودهای شیمیایی و آلی بر عملکرد کمی و کیفی سورگوم رقم پگاه، آزمایشی به صورت طرح بلوک کامل تصادفی با سه تکرار طی فصل زراعی 91-90 در موسسه تحقیقات برنج رشت انجام شد. تیمارهای مورد استفاده، بدون کود و بدون تلقیح (شاهد)، استفاده از کود شیمیایی و بدون تلقیح، تلقیح بذر باpseudomonas fluorescens strain 12 +azotobacter chroococcum strain 41 + بدون کود ش...

2015
VITO CRISMALE

We consider evolutions for a material model which couples scalar damage with strain gradient plasticity, in small strain assumptions. For strain gradient plasticity, we follow the Gurtin-Anand formulation [19]. The aim of the present model is to account for different phenomena: on the one hand the elastic stiffness reduces and the plastic yield surface shrinks due to material’s degradation, on ...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علوم و فنون دریایی خرمشهر - دانشکده علوم دریایی و اقیانوسی (شعبه خرمشهر) 1391

pah ها هیدروکربن های آروماتیکی هستند که از دو یا چند حلقه بنزنی تشکیل شده اند. این ترکیبات دارای منشا انسانی و طبیعی می باشند و بدلیل گستردگی حضور، پایداری، قابلیت تجمع زیستی و فعالیت سرطانزایی به یک نگرانی مهم زیست محیطی تبدیل شده اند. گرچه pahها دستخوش فرآیند های جذب سطحی، تبخیر، تجزیه نوری و تجزیه شیمیایی می شوند اما تجزیه میکروبی اصلی ترین فرآیند حذف این ترکیبات از محیط است. در کشورهای رو ب...

H. Afshari H. Mohammadi Hooyeh M. Mohammadimehr, M.R. Salarkia

In this paper, size-dependent effects on the vibration behavior of Timoshenko microbeams under pre-stress loading embedded in an elastic foundation, using modified strain gradient theory (MSGT) and surface stress effects, were studied. To consider the surface stress effects, the Gurtin–Murdoch continuum mechanical approach was employed. Using Hamilton’s principle, the governing equations of mot...

This paper deals with dynamic Stability of single walled carbon nanotube. Strain gradient theory and Euler-Bernouli beam theory are implemented to investigate the dynamic stability of SWCNT embedded in an elastic medium. The equations of motion were derived by Hamilton principle and non-local elasticity approach. The nonlocal parameter accounts for the small-size effects when dealing with nano-...

In this paper, the dynamic response of resonating nano-beams is investigated using a strain gradient elasticity theory. A nonlinear model is obtained based on the Galerkin decomposition method to find the dynamic response of the investigated beam around its statically deflected position. The mid-plane stretching, axial residual stress and nonlinear interaction due to the electrostatic force on ...

M Ghadiri, M Karimi Asl M Noroozi

The damping vibration characteristics of magneto-electro-viscoelastic (MEV) nanobeam resting on viscoelastic foundation based on nonlocal strain gradient elasticity theory (NSGT) is studied in this article. For this purpose, by considering the effects of Winkler-Pasternak, the viscoelastic medium consists of linear and viscous layers. with respect to the displacement field in accordance with th...

Journal: :International Journal of Solids and Structures 2007

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