• 제목/요약/키워드: Solid mechanics

검색결과 411건 처리시간 0.022초

Modeling of coupled THMC processes in porous media

  • Kowalsky, Ursula;Bente, Sonja;Dinkler, Dieter
    • Coupled systems mechanics
    • /
    • 제3권1호
    • /
    • pp.27-52
    • /
    • 2014
  • For landfill monitoring and aftercare, long-term prognoses of emission and deformation behaviour are required. Landfills may be considered as heterogeneous porous soil-like structures, in which flow and transport processes of gases and liquids interact with local material degradation and mechanical deformation of the solid skeleton. Therefore, in the framework of continuous porous media mechanics a model is developed that permits the investigation of coupled mechanical, hydraulical and biochemical processes in municipal solid waste landfills.

An incompatible 3D solid element for structural analysis at elevated temperatures

  • Yu, Xinmeng;Zha, Xiaoxiong;Huang, Zhaohui
    • Structural Engineering and Mechanics
    • /
    • 제40권3호
    • /
    • pp.393-410
    • /
    • 2011
  • The eight-node 3D solid element is one of the most extensively used elements in computational mechanics. This is due to its simple shape and easy of discretization. However, due to the parasitic shear locking, it should not be used to simulate the behaviour of structural members in bending dominant conditions. Previous researches have indicated that the introduction of incompatible mode into the displacement field of the solid element could significantly reduce the shear locking phenomenon. In this study, an incompatible mode eight-node solid element, which considers both geometric and material nonlinearities, is developed for modelling of structural members at elevated temperatures. An algorithm is developed to extend the state determination procedure at ambient temperature to elevated temperatures overcoming initially converged stress locking when the external load is kept constant. Numerical studies show that this incompatible element is superior in terms of convergence, mesh insensitivity and reducing shear locking. It is also showed that the solid element model developed in this paper can be used to model structural behaviour at both ambient and elevated temperatures.

Surface and size dependent effects on static, buckling, and vibration of micro composite beam under thermo-magnetic fields based on strain gradient theory

  • Mohammadimehr, Mehdi;Mehrabi, Mojtaba;Hadizadeh, Hasan;Hadizadeh, Hossein
    • Steel and Composite Structures
    • /
    • 제26권4호
    • /
    • pp.513-531
    • /
    • 2018
  • In this article, static, buckling and free vibration analyses of a sinusoidal micro composite beam reinforced by single-walled carbon nanotubes (SWCNTs) with considering temperature-dependent material properties embedded in an elastic medium in the presence of magnetic field under transverse uniform load are presented. This system is used at micro or sub micro scales to enhance the stiffness of micro composite structures such as bar, beam, plate and shell. In the present work, the size dependent effects based on surface stress effect and modified strain gradient theory (MSGT) are considered. The generalized rule of mixture is employed to predict temperature-dependent mechanical and thermal properties of micro composite beam. Then, the governing equations of motions are derived using Hamilton's principle and energy method. Numerical results are presented to investigate the influences of material length scale parameters, elastic foundation, composite fiber angle, magnetic intensity, temperature changes and carbon nanotubes volume fraction on the bending, buckling and free vibration behaviors of micro composite beam. There is a good agreement between the obtained results by this research and the literature results. The obtained results of this study demonstrate that the magnetic intensity, temperature changes, and two parameters elastic foundations have important effects on micro composite stiffness, while the magnetic field has greater effects on the bending, buckling and free vibration responses of micro composite beams. Moreover, it is shown that the effects of surface layers are important, and observed that the changes of carbon nanotubes volume fraction, beam length-to-thickness ratio and material length scale parameter have noticeable effects on the maximum deflection, critical buckling load and natural frequencies of micro composite beams.

A comprehensive stress analysis in a functionally graded spherical pressure vessel: Thermo-elastic, elastoplastic and residual stress analysis

  • Thaier J. Ntayeesh;Mohsen Kholdi;Soheil Saeedi;Abbas Loghman;Mohammad Arefi
    • Steel and Composite Structures
    • /
    • 제52권3호
    • /
    • pp.377-390
    • /
    • 2024
  • Analyzing thermoelastic, elastoplastic, and residual stresses is pivotal for deepening our insights into material characteristics, particularly in the engineering of advanced materials like functionally graded materials (FGM). This research delves into these stress types within a thick-walled sphere composed of Al-SiC FGM, employing a detailed successive approximation method (SAM) to pinpoint stress distributions under varied loading scenarios. Our investigation centers on how the sphere's structure responds to different magnitudes of internal pressure. We discover that under various states-thermoelastic, elastoplastic, and residual-the radial stresses are adversely impacted, manifesting negative values due to the compressive nature induced by internal pressures. Notably, the occurrence of reverse yielding, observed at pressures above 410 MPa, merits attention due to its significant implications on the sphere's structural integrity and operational efficacy. Employing the SAM allows us to methodically explore the nuanced shifts in material properties across the sphere's thickness. This study not only highlights the critical behaviors of Al-SiC FGM spheres under stress but also emphasizes the need to consider reverse yielding phenomena to maintain safety and reliability in their application. We advocate for ongoing refinement of analytical techniques to further our understanding of stress behaviors in various FGM configurations, which could drive the optimized design and practical application of these innovative materials in diverse engineering fields.

Temperature effects on brittle fracture in cracked asphalt concretes

  • Ayatollahi, Majid-Reza;Pirmohammad, Sadjad
    • Structural Engineering and Mechanics
    • /
    • 제45권1호
    • /
    • pp.19-32
    • /
    • 2013
  • Cracking at low temperatures is one of the frequently observed modes of failure in asphalt concretes. In this investigation, fracture tests were performed on cracked asphalt concrete subjected to pure mode I and pure mode II loading at different subzero temperatures. An improved semi-circular bend (SCB) specimen containing a vertical crack was used to conduct the experiments. The SCB specimens produced from the gyratory compacted cylindrical samples were compressively loaded, and critical stress intensity factors, $K_{If}$ and $K_{IIf}$, were then calculated using peak loads obtained from the tests. The experimental results showed that with decreasing the temperature, mode I and mode II critical stress intensity factors increased first but below a certain temperature they both decreased. It was also found that at a fixed temperature, the mode II fracture resistance of the asphalt concrete was higher than its mode I fracture resistance.

Size dependent effect on deflection and buckling analyses of porous nanocomposite plate based on nonlocal strain gradient theory

  • Khazaei, Pegah;Mohammadimehr, Mehdi
    • Structural Engineering and Mechanics
    • /
    • 제76권1호
    • /
    • pp.27-56
    • /
    • 2020
  • In this paper, the deflection and buckling analyses of porous nano-composite piezoelectric plate reinforced by carbon nanotube (CNT) are studied. The equations of equilibrium using energy method are derived from principle of minimum total potential energy. In the research, the non-local strain gradient theory is employed to consider size dependent effect for porous nanocomposite piezoelectric plate. The effects of material length scale parameter, Eringen's nonlocal parameter, porosity coefficient and aspect ratio on the deflection and critical buckling load are investigated. The results indicate that the effect of porosity coefficient on the increase of the deflection and critical buckling load is greatly higher than the other parameters effect, and size effect including nonlocal parameter and the material length scale parameter have a lower effect on the deflection increase with respect to the porosity coefficient, respectively and vice versa for critical buckling load. Porous nanocomposites are used in various engineering fields such as aerospace, medical industries and water refinery.