On two simple virtual Kirchhoff-Love plate elements for isotropic and anisotropic materials

The virtual element method allows to revisit the construction of Kirchhoff-Love elements because the $$C^1$$ C 1 -continuity condition is much easier to handle in the VEM framework than in the traditional Finite Elements methodology. Here we study the two most simple VEM elements suitable for Kirchhoff-Love plates as stated in Brezzi and Marini (Comput Methods Appl Mech Eng 253:455–462, 2013). The formulation contains new ideas and different approaches for the stabilisation needed in a virtual element, including classic and energy stabilisations. An efficient stabilisation is crucial in the case of $$C^1$$ C 1 -continuous elements because the rank deficiency of the stiffness matrix associated to the projected part of the ansatz function is larger than for $$C^0$$ C 0 -continuous elements. This paper aims at providing engineering inside in how to construct simple and efficient virtual plate elements for isotropic and anisotropic materials and at comparing different possibilities for the stabilisation. Different examples and convergence studies discuss and demonstrate the accuracy of the resulting VEM elements. Finally, reduction of virtual plate elements to triangular and quadrilateral elements with 3 and 4 nodes, respectively, yields finite element like plate elements. It will be shown that these $$C^1$$ C 1 -continuous elements can be easily incorporated in legacy codes and demonstrate an efficiency and accuracy that is much higher than provided by traditional finite elements for thin plates.

Numerical Application of Effective Thickness Approach to Box Aluminium Sections

The ultimate behaviour of aluminium members subjected to uniform compression or bending is strongly influenced by local buckling effects which occur in the portions of the section during compression. In the current codes, the effective thickness method (ETM) is applied to evaluate the ultimate resistance of slender cross-sections affected by elastic local buckling. In this paper, a recent extension of ETM is presented to consider the local buckling effects in the elastic-plastic range and the interaction between the plate elements constituting the cross-section. The theoretical results obtained with this approach, applied to box-shaped aluminium members during compression or in bending, are compared with the experimental tests provided in the scientific literature. It is observed that the ETM is a valid and accurate tool for predicting the maximum resistance of box-shaped aluminium members during compression or in bending.

Design of stiffened panels for stress and buckling via topology optimization

This paper investigates the weight minimization of stiffened panels simultaneously optimizing sizing, layout, and topology under stress and buckling constraints. An effective topology optimization parameterization is presented using multiple level-set functions. Plate elements are employed to model the stiffened panels. The stiffeners are parametrized by implicit level-set functions. The internal topologies of the stiffeners are optimized as well as their layout. A free-form mesh deformation approach is improved to adjust the finite element mesh. Sizing optimization is also included. The thicknesses of the skin and stiffeners are optimized. Bending, shear, and membrane stresses are evaluated at the bottom, middle, and top surfaces of the elements. A p-norm function is used to aggregate these stresses in a single constraint. To solve the optimization problem, a semi-analytical sensitivity analysis is performed, and the optimization algorithm is outlined. Numerical investigations demonstrate and validate the proposed method.

Stress Concentration in Bounded Compositeplates with Carbon Reinforcement

The research purpose is to develop an approach for determining the stress concentration near the holes in composite structure elements reinforced with carbon fibres. The research is performed on the basis of a numerical-analytic approach using the method of singular integral equations. The paper studies the stress concentration near the holes in composite plate elements of the structures, which are reinforced with carbon fibres. The stresses are determined based on the singular integral equations. The integral equations are solved numerically using the mechanical quadrature method. The stress in the strip is studied at: longitudinal tension; pure bending; three-point bending; with periodically spaced holes. An approach to calculating the stresses in composite strips weakened by holes of different shapes, based on the method of integral equations, has been developed. The equation kernels are formulated on the basis of Green's functions, under which the boundary conditions on straight-line boundaries are satisfied identically. A methodology for calculating the stress concentration near the holes of arbitrary shape in plate elements of the structures has been developed. The results obtained can be used when calculating the strength of composite materials reinforced with carbon fibres.

Boundary-Adapted Numerical Modeling of Flow in a Hydrostatic Leadscrew

A new method is presented to model and predict the flow fields of the hydrostatic leadscrews with greater accuracy. It is different from those available methods, in which various bearings are assumed to be equivalent to the screw-nut pair within a pitch by various means. In this new method, a helical coordinate system adapting to the boundaries of the flow fields is constructed, which makes the screw-nut meshing clearance calculated more accurate. Based on the finite difference method (FDM), the meshing clearance is discretized into a number of flow fields, which are created by numerous couples of parallel-plate elements moving relatively along the helicoid. The numerical model is solved in MATLAB, and the analyses about the pressure fields demonstrate its favorable performances in reflecting the actual flow fields. Furthermore, the simulation results are compared with the experimental values, confirming the feasibility of the proposed method.

Micromechanical modeling of nacre-mimetic Ti3C2-MXene nanocomposites with viscoelastic polymer matrix

A new two-dimensional nanomaterial—Titanium Carbide MXene (Ti3C2-MXene)—was reported in 2011. In this work, the microscale models of Ti3C2-MXene nanomaterial are considered with polymer matrix. The nanocomposites are modeled using nacre-mimetic brick-and-mortar assembly configurations due to enhanced mechanical properties and interlocking mechanism between the Ti3C2-MXene (brick) and polymer matrices (mortar). The polymer matrix material (Epoxy-resin) is modeled with elastic and viscoelastic behavior (Kelvin–Voigt Model). The Finite Element Method is used for numerical analysis of the microscale models with the multi-point constraint method to include Ti3C2-MXene fillers in the polymer matrix. Ti3C2-MXenes are considered as thick plate elements with transverse shear effects. The response of elastic and viscoelastic models of polymer matrix are studied. Finally, a tensile and compressive load is applied at the microscale and the effective load transfer due to nacre-mimetic configuration is discussed. This paper provides nacre-mimetic models to pre-design the nanocomposite for optimal performance with damage resistance and enhanced strength.

Micromechanical Modeling of Nacre-mimetic Ti3C2-MXene Nanocomposites with Viscoelastic Polymer Matrix

A new two-dimensional nanomaterial – Titanium Carbide MXene (Ti3C2-MXene) – was reported in 2011. In this work, the microscale models of Ti3C2-MXene nanomaterial are considered with polymer matrix. The nanocomposites are modeled using nacre-mimetic brick-and-mortar assembly configurations due to enhanced mechanical properties and interlocking mechanism between the Ti3C2-MXene (brick) and polymer matrices (mortar). The polymer matrix material (Epoxy-resin) is modeled with elastic and viscoelastic behavior (Kelvin-Voigt Model). The Finite Element Method is used for numerical analysis of the microscale models with the multi-point constraint method to include Ti3C2-MXene fillers in the polymer matrix. Ti3C2-MXenes are considered as thick plate elements with transverse shear effects. The response of elastic and viscoelastic models of polymer matrix are studied. Finally, a tensile and compressive load is applied at the microscale and the effective load transfer due to nacre-mimetic configuration is discussed. This paper provides nacre-mimetic models to pre-design the nanocomposite for optimal performance with damage resistance and enhanced strength.

EVALUATION OF SEKOLAH ISLAM TERPADU (SIT) ALIYA BOGOR BUILDING STRUCTURE SYSTEM BASED ON THE REQUIREMENTS OF SNI 2847:2019

<p class="ListParagraph1">Sekolah Islam Terpadu (SIT) Aliya Bogor is located in west Bogor district, Bogor city, West Java, was founded in 200, thus the standards used by planning consultant in building planning using old standard, where these standards have been updated with current standard, namely SNI 2847:2019. The evaluation carried out in this study based on requirements SNI 2847:2019 knowing the outcome of building that was said to be safe used help software ETABS) and SpColumn. Length of building of Umar Bin Khatab A and B are 18,60 meter;23,65 meter.Building area of building Umar Bin Khatab A and B are 541,26 m²; 865,59 m². Concrete quality assessment (fc’) that came from the test of hammer test column elements, beam elements, and plate elements as big 23,74 Mpa;26,59 Mpa;26,59 Mpa. After analysis some of to experience overstrength. The original column dimension In Building of Umar Bin Khatab A was K25x25 with shear reinforcement is Ø16-150 enlarge to K40x40 with shear reinforcement is Ø39-150 and beam dimension 20x40 enlarge to 35x55. On the building of Umar Bin Khatab B was K25x25 with shear reinforcement Ø16-150 enlarge to K40x40 with shear reinforcement Ø25-150, with the original beam dimension 20x40 enlarge to 30x55. The cost budget in the building of Umar Bin Khatab A is Rp 74.158.600,00 and in building of Umar Bin Khatab B is Rp 61.084.600,00.</p>