•We present the strain-smoothed MITC3+ shell finite element for nonlinear analysis.•The total Lagrangian formulation is adopted allowing for large displacement kinematics.•Its performance is ...demonstrated in geometrical and material nonlinear analyses.
This paper presents the strain-smoothed MITC3+ shell finite element for nonlinear analysis. The strain-smoothed MITC3+ shell element, recently developed for linear analysis, significantly improves the membrane behavior of the MITC3+ shell element while retaining its excellent bending behavior. The achievement is attained by adopting the strain-smoothed element (SSE) method to the membrane strain field. To extend its formulation to nonlinear analysis, the total Lagrangian formulation is employed allowing for large displacements and rotations. Through various numerical examples, we verify that the strain-smoothed MITC3+ shell element also shows the superior performance in geometrical and material nonlinear analyses.
Summary
The seismic performance of unreinforced masonry structures is strongly associated with the interaction between in‐plane and out‐of‐plane mechanisms. The seismic response of these structures ...has been thoroughly investigated by means of experimental testing, analytical procedures, and computational approaches. Within the framework of the numerical simulations, models based on the finite element method provide a good prediction of the seismic performance of unreinforced masonry structures. However, they usually require a high computational cost and advanced user expertise to define appropriate mechanical properties and to interpret the numerical results. Because of these limitations, simplified models for practical applications have been developed during the last decades. Despite this, a great number of these models focus mostly on the evaluation of the in‐plane response, assuming box (or integral) behavior of the structure. In this paper, a simplified macroelement modeling approach is used to simulate the seismic response of 2 masonry prototypes taking into consideration the combined in‐plane and out‐of‐plane action. The numerical investigations were performed in the static and dynamic fields by using pushover analyses and nonlinear dynamic analyses respectively. The latter is a novel implementation of a model previously developed for static analysis. The results obtained from this study are in good agreement with those provided by a detailed nonlinear continuum FE approach, demonstrating the applicability of this macroelement model with a significant reduction of the computational cost.
The linear and nonlinear forced vibration response of axially functionally graded (AFG) cylindrical truncated conical and imperfect microbeam subjected to the dynamic harmonically load carried out in ...the presented research. Based on a couple of modified couple stress theory, the Euler-Bernoulli beam theory and von-Kármán theory, the linear and nonlinear governing equations and related boundary conditions for dynamic response of micro-size tubes are derived employing the Hamilton principle. We considered the uniform and nonuniform functions for the cross-section, in which the convex, linear and exponential functions are the nonuniform sections, and the porosity is regarded as an imperfection. The generalized differential quadrature method (GDQM) is used to prepare the initial conditions for homotopy perturbation (HP) techniques as the semi-analytical approach to calculate the linear and nonlinear results of dynamic responses. The obtained linear and nonlinear results of the free and forced vibration response show the negative and positive effects of some parameters such as the porosity parameter, the nonlinear amplitude, the small-scale parameter, AFG parameter, and different cross-section impact on the dynamic deflection and natural frequency of micro-scale tube and beams with both clamped and simply-supported boundary conditions.
Numerous experiments and prior analyses have confirmed that the angle of incidence of a seismic wave can significantly affect ground response and dynamic soil–structure interaction (SSI) behavior. ...Realistically, obliquely incident waves will be generated due to the soil heterogeneity and stratigraphy, which can lead into complex wave propagation and scattering patterns. In this study, we propose a novel methodology that (i) utilizes the wave potential theory to derive the 3D time‐domain analytical solutions for free‐field response under obliquely incident SV waves in layered soil media; (ii) makes use of high‐fidelity numerical tools—namely, the domain reduction method (DRM) and the perfectly matched layers (PMLs)—to inject the obliquely incident waves into the domain of interest and to absorb the outgoing scattered motions, respectively; (iii) enables nonlinear time‐domain site response and SSI analyses that feature an advanced constitutive model for soil. Finally, a 3D 20‐story steel building is modeled as a case study. The building rests on a two‐layer half‐space and is subjected to an obliquely incident seismic wave. The SV wave's angles of incidence are varied to investigate its effects on structural responses, such as horizontal, vertical, and rotational floor accelerations, as well as interstory drift ratios.
In this paper, we present the first attempt at modelling the impact of economic policy uncertainty on renewable energy consumption in the USA using monthly data from 1986 to 2019. By implementing ...recent nonparametric (nonlinear) econometric approaches, we find that our models suffer from nonlinearity and smooth, as well as abrupt structural changes. The nonparametric unit root tests indicate non-stationarity of the model variables while the cointegration suggests the presence of nonlinear cointegration. The Granger causality analyses establish robust nonlinear causation in both directions between the policy uncertainty and renewable energy variables, with one exception: from geothermal energy to the three-component index of uncertainty. The nonparametric regressions exhibit a negative long-run association between policy uncertainty and renewable energy consumption, i.e., higher economic policy uncertainty lowers renewable energy consumptions and vice-versa. These findings have robust policy implications as they underscore the importance of governments, policymakers and concerned agents to maintain uniformity in economic policy to encourage renewable energy consumption in the USA.
Recent theoretical work indicates that the neutrino radiation in core-collapse supernovae may be susceptible to flavor instabilities that set in far behind the shock, grow extremely rapidly, and have ...the potential to profoundly affect supernova dynamics and composition. Here we analyze the nonlinear collective oscillations that are prefigured by these instabilities. We demonstrate that a zero crossing in nνe−nνe as a function of propagation angle is not sufficient to generate instability. Our analysis accounts for this fact and allows us to formulate complementary criteria. Using fornax simulation data, we show that fast collective oscillations qualitatively depend on how forward peaked the neutrino angular distributions are.
Isogeometric analysis (IGA) has become a strong tool for analysis of shell structures, which can be considered as a powerful alternative to the standard finite element method (FEM). Besides several ...advantages of IGA over FEM in geometric nonlinear analysis of the shells, it has some drawbacks corresponding to tensor-product of B-spline and NURBS surfaces. One of the solutions to eliminate or at least reduce the effects of the mentioned shortcomings is to combine IGA with the other methods, such as FEM. In the present paper, a novel version of the finite strip method (FSM) is developed to carry out the geometric nonlinear analysis, which employs a combination of FEM and IGA in the transversal and longitudinal directions, respectively and is named isogeometric B-spline finite strip method (IG-SFSM). The strip elements have been formulated based on the Degenerated-Shell method for Updated-Lagrangian (UL) approach. Then, it is examined by some examples incorporating various geometries, boundary conditions (BCs), and material properties, such as laminated composites and sandwich FGMs. The results exhibited that, to achieve the complicated nonlinear equilibrium paths of the shells, IG-SFSM requires a lower number of degrees of freedom (DOFs) and, consequently, computational efforts comparing to the other common methods, such as finite element and mesh-free methods.
•An enhanced version of FSM with lower limitations in analysis of shells is proposed.•The shortcomings of IGA and FEM is reduced.•Computational cost is significantly reduced in comparison to conventional methods like FEM and EFG.•IG-SFSM is able to obtain the equilibrium paths with various instabilities.•Various geometries, boundary conditions, and material properties are considered to examine the method.
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