Analysis of Complex Structures Coupling Variable Kinematics One-Dimensional Models

2014 ◽  
Author(s):  
Erasmo Carrera ◽  
Enrico Zappino
Keyword(s):  
Mechanical Design ◽  
Computational Cost ◽  
Advanced Materials ◽  
Complex Structures ◽  
Displacement Fields ◽  
One Dimensional ◽  
Classical Models ◽  
Kinematic Models ◽  
Carrera Unified Formulation ◽  
Dimensional Models

One-dimensional models are widely used in mechanical design. Classical models, Euler-Bernoulli or Timoshenko, ensure a low computational cost but are limited by their assumptions, many refined models were proposed to overcome these limitations and extend one-dimensional models at the analysis of complex geometries or advanced materials. In this work a new approach is proposed to couple different kinematic models. A new finite element is introduced in order to connect one-dimensional elements with different displacement fields. The model is derived in the frameworks of the Carrera Unified Formulation (CUF), therefore the formulation can be written in terms of fundamental nuclei. The results show that the use variable kinematic models allows the computational costs to be reduced without reduce the accuracy, moreover, refined-one dimensional models can be used in the analysis of complex structures.

High-Fidelity One-Dimensional Models for Tapered Structures Analyses

2016 ◽  
Author(s):  
Andrea Viglietti ◽  
Enrico Zappino ◽  
Erasmo Carrera
Keyword(s):  
Computational Cost ◽  
Displacement Fields ◽  
One Dimensional ◽  
Thin Walled Structures ◽  
Solid Models ◽  
Stress And Displacement Fields ◽  
Carrera Unified Formulation ◽  
Dimensional Models ◽  
Polynomial Expansions ◽  
Tapered Structures

This paper presents the static analysis of tapered structures made of composite material using 1D models. These models are based on a one-dimensional formulation derived using the Carrera Unified Formulation (CUF). This formulation allows us to obtain 3D-like results thanks to the use of polynomial expansions to describe the displacement field over the cross-section. According to the types of expansion used, different classes of refined one-dimensional elements are obtained. In this work the Lagrange expansions were used. The use of LE models allows each structural component to bo considered separately; this approach is called component wise (CW). The thin-walled structures are usually made of composite materials, in particular, the aeronautical structures. For this reason, these kinds of structures are taken into account. The stress and displacement fields due to simple load cases have been obtained. The results have been compared with those obtained using commercial tools. The results show the capability of the present refined one-dimensional models to achieve results usually obtained by the use of solid models and therefore, with higher computational cost.

Node-Dependent Kinematic One-Dimensional Models for the Analysis of Rotating Structures

2017 ◽  
Author(s):  
Erasmo Carrera ◽  
Matteo Filippi ◽  
Enrico Zappino
Keyword(s):  
Equations Of Motion ◽  
Computational Cost ◽  
Three Dimensional ◽  
Element Model ◽  
One Dimensional ◽  
Thin Walled Structures ◽  
Centrifugal Stiffening ◽  
Dimensional Finite Element ◽  
Classical Models ◽  
Kinematic Models

In this paper, the dynamics of rotating structures has been studied using a refined one-dimensional finite element model with a node-dependent kinematics. The present approach has been used to derive models where refined theories are used only in the region in which they are required and classical models elsewhere. This produces a reduction in the computational cost without a reduction in the accuracy of the analysis. The equations of motion have been derived in a three-dimensional fashion and they include all contributions due to the rotational speed, namely the gyroscopic, the spin softening, and the centrifugal stiffening terms. Classical and higher-order refined models have been established with the Carrera Unified Formulation. The numerical model has been assessed and then a number of applications to thin-walled structures have been proposed. The current methodology appears very effective when rotors are constituted of components with different deformability such as compact shafts and disks. The results have been compared with those obtained from uniform kinematic models and convergence analyses have been performed. The results show the efficiency of the proposed model.

A Component-Wise Approach to Analyse a Composite Launcher Structure Subjected to Loading Factor

2016 ◽  
Author(s):  
Tommaso Cavallo ◽  
Alfonso Pagani ◽  
Enrico Zappino ◽  
Erasmo Carrera
Keyword(s):  
Composite Structures ◽  
Computational Cost ◽  
Free Vibration Analysis ◽  
High Strength ◽  
3D Models ◽  
Advanced Materials ◽  
Space Structures ◽  
One Dimensional ◽  
Computational Costs ◽  
The One

The space structures are realized by combining skin and reinforced components, such as longitudinal reinforcements called stringers and transversal reinforcements called ribs. These reinforced structures allow two main design requirements to be satisfied, the former is the light weight and the latter is a high strength. Solid models (3D) are widely used in the Finite Element Method (FEM) to analyse space structures because they have a high accuracy, in contrast they also have a high number of degrees of freedoms (DOFs) and huge computational costs. For these reasons the one-dimensional models (1D) are gaining success as alternative to 3D models. Classical models, such as Euler-Bernoulli or Timoshenko beam theories, allow the computational cost to be reduced but they are limited by their assumptions. Different refined models have been proposed to overcome these limitations and to extend the use of 1D models to the analysis of complex geometries or advanced materials. In this work very complex space structures are analyzed using 1D model based on the Carrera Unified Formulation (CUF). The free-vibration analysis of isotropic and composite structures are shown. The effects of the loading factor on the natural frequencies of an outline of launcher similar to the Arian V have been investigated. The results highlight the capability of the present refined one-dimensional model to reduce the computational costs without reducing the accuracy of the analysis.

A Node-Dependent Kinematic Approach for Rotordynamics Problems

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Matteo Filippi ◽  
Enrico Zappino ◽  
Erasmo Carrera
Keyword(s):  
Dynamic Analysis ◽  
Computational Cost ◽  
Three Dimensional ◽  
Governing Equations ◽  
Three Dimensional Model ◽  
Flexible Supports ◽  
Out Of Plane ◽  
Kinematic Models ◽  
Carrera Unified Formulation ◽  
Kinematic Approach

This paper presents the dynamic analysis of rotating structures using node-dependent kinematics (NDK) one-dimensional (1D) elements. These elements have the capabilities to assume a different kinematic at each node of a beam element, that is, the kinematic assumptions can be continuously varied along the beam axis. Node-dependent kinematic 1D elements have been extended to the dynamic analysis of rotors where the response of the slender shaft, as well as the responses of disks, has to be evaluated. Node dependent kinematic capabilities have been exploited to impose simple kinematic assumptions along the shaft and refined kinematic models where the in- and out-of-plane deformations appear, that is, on the disks. The governing equations of the rotordynamics problem have been derived in a unified and compact form using the Carrera unified formulation. Refined beam models based on Taylor and Lagrange expansions (LEs) have been considered. Single- and multiple-disk rotors have been investigated. The effects of flexible supports have also been included. The results show that the use of the node-dependent kinematic elements allows the accuracy of the model to be increased only where it is required. This approach leads to a reduction of the computational cost compared to a three-dimensional model while the accuracy of the results is preserved.

scholarly journals Development of a synchrotron powder diffractometer with a one-dimensional X-ray detector for analysis of advanced materials

2013 ◽  
Vol 121 (1411) ◽  
pp. 287-290 ◽  
Author(s):  
Masahiko TANAKA ◽  
Yoshio KATSUYA ◽  
Yoshitaka MATSUSHITA ◽  
Osami SAKATA
Keyword(s):  
Advanced Materials ◽  
One Dimensional ◽  
X Ray ◽  
Powder Diffractometer

scholarly journals Collision Avoidance and Stability Study of a Self-Reconfigurable Drainage Robot

Sensors ◽  
2021 ◽  
Vol 21 (11) ◽  
pp. 3744
Author(s):  
Rizuwana Parween ◽  
M. A. Viraj J. Muthugala ◽  
Manuel V. Heredia ◽  
Karthikeyan Elangovan ◽  
Mohan Rajesh Elara
Keyword(s):  
Collision Avoidance ◽  
Mechanical Design ◽  
Side Wall ◽  
Stability Study ◽  
Directional Movement ◽  
Kinematic Models ◽  
Wall Collision ◽  
Inspection And Maintenance ◽  
Rolling Wheel ◽  
Hybrid Locomotion

The inspection and maintenance of drains with varying heights necessitates a drain mapping robot with trained labour to maintain community hygiene and prevent the spread of diseases. For adapting to level changes and navigating in the narrow confined environments of drains, we developed a self-configurable hybrid robot, named Tarantula-II. The platform is a quadruped robot with hybrid locomotion and the ability to reconfigure to achieve variable height and width. It has four legs, and each leg is made of linear actuators and modular rolling wheel mechanisms with bi-directional movement. The platform has a fuzzy logic system for collision avoidance of the side wall in the drain environment. During level shifting, the platform achieves stability by using the pitch angle as the feedback from the inertial measuring unit (IMU) mounted on the platform. This feedback helps to adjust the accurate height of the platform. In this paper, we describe the detailed mechanical design and system architecture, kinematic models, control architecture, and stability of the platform. We deployed the platform both in a lab setting and in a real-time drain environment to demonstrate the wall collision avoidance, stability, and level shifting capabilities of the platform.

scholarly journals New insights on homogenization for hexagonal-shaped composites as Cosserat continua

Meccanica ◽  
2021 ◽  
Author(s):  
Marco Colatosti ◽  
Nicholas Fantuzzi ◽  
Patrizia Trovalusci ◽  
Renato Masiani
Keyword(s):  
Continuum Theory ◽  
Representative Elementary Volume ◽  
Elementary Volume ◽  
Displacement Fields ◽  
Micropolar Continuum ◽  
Rigid Particles ◽  
Hexagonal Shape ◽  
Classical Models ◽  
Elastic Interfaces ◽  
Cosserat Continua

AbstractIn this work, particle composite materials with different kind of microstructures are analyzed. Such materials are described as made of rigid particles and elastic interfaces. Rigid particles of arbitrary hexagonal shape are considered and their geometry is described by a limited set of parameters. Three different textures are analyzed and static analyses are performed for a comparison among the solutions of discrete, micropolar (Cosserat) and classical models. In particular, the displacements of the discrete model are compared to the displacement fields of equivalent micropolar and classical continua realized through a homogenization technique, starting from the representative elementary volume detected with a numeric approach. The performed analyses show the effectiveness of adopting the micropolar continuum theory for describing such materials.

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