Many scientific and engineering problems, including soil dynamics problems with elasto-plasticity, are involved in solving partial differential equations numerically. The correctness and accuracy of the solutions have to be checked in a rigorous way, i.e., the code used to solve the problems has to be verified. In the field of fluid dynamics, the method of manufactured solutions (MMS) has been proposed and accepted as a de facto standard for code verification. However, we show in this paper that MMS procedures cannot be used directly for soil dynamics problems considering elasto-plasticity. The main difficulty is due to the soil elasto-plasticity which is generally formulated in a rate form coupled by an algebraic constraint (the yield surface). Instead, we propose the method of numerically manufactured solutions (MNMS) for verifying elasto-plastic problems. The concepts and the workflows of MNMS are explained in detail and two simple demonstrations are presented. Though the numerical demonstrations in the present paper are primitive, the capability of the proposed MNMS, as a general and systematic way for developers and users of numerical simulations to verify their codes being used, should not be underestimated.
In this paper a coupled elasto-plastic and damage model is presented and applied to predict the ductile damage accumulation under non-proportional loading conditions. The ductile damage constitutive equations, within the framework of the continuum damage mechanics, were coupled with the unconventional plasticity model Extended Subloading Surface1) in order to investigate the degradation of the mechanical performance of metals under the development of plastic deformation. Moreover, the tangential inelastic contribution2) was introduced to simulate the acceleration of the damage evolution observed during experiments carried out under non-proportional loading paths.
External strengthening of Reinforcement Concrete (RC) structures using epoxy-bonded Fiber Reinforced Polymer (FRP) sheets has some negative aspects, such as interfacial debonding and poor resistance ability of epoxy resin for fire and ultraviolet (UV), in addition to the working environment restrictions. To overcome some of those negative aspects, FRP grid bonded with Polymer Cement Mortar (PCM) to strengthen RC structures is developed and proposed in this study. The main objective of this paper is to study the efficiency between Basalt FRP grids and PCM in the flexural strengthening of RC beams. A tensile test was first conducted to determine the static longitudinal tensile strength and maximum elongation properties of the different BFRP grids. Then, the well-known double shear test was conducted to determine the bond mechanism between BFRP grids and concrete. Finally, the flexural behavior of the RC beam externally strengthened with BFRP grids was investigated through a four-point bending test. The results showed the efficiency of using BFRP grids as external strengthening method, as well as the stress-strain relationship of RC beams cross-section shows the compatibility with flexural theory.
内部侵食は観測が困難である土中で進行するため，問題の解決には数値計算が有用な手法となる．本研究では浸透流による水みちの拡大過程に焦点を当て，浸透流と土粒子の両方をLattice Boltzmann MethodとDiscrete Element Methodを連成させて直接解いた．粒子間の固着モデルを導入することで，粘性土の粘着特性を表現し，土粒子間の固着力を表すパラメータと土試料に作用する両端の圧力差を変えながら，繰り返しの検討を行った．その結果，土粒子間の固着力に大きさに応じて，土粒子集合体としての侵食に対する抵抗力の大きさが変化することを表すことができ，従来の2次元での応用例より再現性が高まることが確認できた．