scholarly journals Numerical and Experimental Extraction of Dynamic Parameters for Pyramidal Truss Core Sandwich Beams with Laminated Face Sheets

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5199 ◽  
Author(s):  
Miroslaw Wesolowski ◽  
Mariusz Ruchwa ◽  
Eduards Skukis ◽  
Andrejs Kovalovs
Keyword(s):  
Three Dimensional ◽  
Sandwich Beam ◽  
Essential Elements ◽  
Mode Shapes ◽  
Sandwich Beams ◽  
Dynamic Parameters ◽  
Additional Layer ◽  
Out Of Plane ◽  
Pyramidal Truss ◽  
Loss Factors

Sandwich beams that are composed of laminated face sheets and aluminum pyramidal truss cores are considered to be essential elements of building and aerospace structures. In this paper, a methodology for the experimental and numerical analysis of such structures is presented in order to support their industrial application. The scope of the present research covers both the experimental and numerical extraction of the dynamic parameters of the sandwich beams. Vibration tests are performed while using an optical system for three-dimensional vibrations sensing. The in-plane and out-of-plane vibration modes can thus be examined. A detailed numerical model of the sandwich beam is developed, including an adhesive joint (an additional layer of material) between the parent components of the beam. The numerically predicted modal parameters (eigenfrequencies, mode shapes, modal loss factors) are comported with their corresponding experimentally-obtained values. The modal loss factors are predicted based on the strain energy method, for which a brief theoretical introduction is provided. The obtained experimental and numerical results coincide with good accuracy. The circumstances for possible model simplifications are provided depending on the solution objectives.

In-Plane Vibration Modes of Arbitrarily Thick Disks

1997 ◽  
Author(s):  
Kevin I. Tzou ◽  
Jonathan A. Wickert ◽  
Adnan Akay
Keyword(s):  
Natural Frequencies ◽  
Arbitrary Dimension ◽  
Three Dimensional ◽  
Mode Shapes ◽  
Vibration Modes ◽  
Three Dimensional Model ◽  
Bending Vibration ◽  
Annular Disk ◽  
Out Of Plane ◽  
Plane Bending

Abstract The three-dimensional vibration of an arbitrarily thick annular disk is investigated for two classes of boundary conditions: all surfaces traction-free, and all free except for the clamped inner radius. These two models represent limiting cases of such common engineering components as automotive and aircraft disk brakes, for which existing models focus on out-of-plane bending vibration. For a disk of significant thickness, vibration modes in which motion occurs within the disk’s equilibrium plane can play a substantial role in setting its dynamic response. Laboratory experiments demonstrate that in-plane modes exist at frequencies comparable to those of out-of-plane bending even for thickness-to-diameter ratios as small as 10−1. The equations for three-dimensional motion are discretized through the Ritz technique, yielding natural frequencies and mode shapes for coupled axial, radial, and circumferential deformations. This treatment is applicable to “disks” of arbitrary dimension, and encompasses classical models for plates, bars, cylinders, rings, and shells. The solutions so obtained converge in the limiting cases to the values expected from the classical theories, and to ones that account for shear deformation and rotary inertia. The three-dimensional model demonstrates that for geometries within the technologically-important range, the natural frequencies of certain in- and out-of-plane modes can be close to one another, or even identically repeated.

In-Plane Vibration Modes of Arbitrarily Thick Disks

1998 ◽  
Vol 120 (2) ◽  
pp. 384-391 ◽  
Author(s):  
K. I. Tzou ◽  
J. A. Wickert ◽  
A. Akay
Keyword(s):  
Natural Frequencies ◽  
Arbitrary Dimension ◽  
Three Dimensional ◽  
Mode Shapes ◽  
Vibration Modes ◽  
Three Dimensional Model ◽  
Bending Vibration ◽  
Annular Disk ◽  
Out Of Plane ◽  
Plane Bending

The three-dimensional vibration of an arbitrarily thick annular disk is investigated for two classes of boundary conditions: all surfaces traction-free, and all free except for the clamped inner radius. These two models represent limiting cases of such common engineering components as automotive and aircraft disk brakes, for which existing models focus on out-of-plane bending vibration. For a disk of significant thickness, vibration modes in which motion occurs within the disk’s equilibrium plane can play a substantial role in-setting its dynamic response. Laboratory experiments demonstrate that in-plane modes exist at frequencies comparable to those of out-of-plane bending even for thickness-to-diameter ratios as small as 10−1. The equations for three-dimensional motion are discretized through the Ritz technique, yielding natural frequencies and mode shapes for coupled axial, radial, and circumferential deformations. This treatment is applicable to “disks” of arbitrary dimension, and encompasses classical models for plates, bars, cylinders, rings, and shells. The solutions so obtained converge in the limiting cases to the values expected from the classical theories, and to ones that account for shear deformation and rotary inertia. The three-dimensional model demonstrates that for geometries within the technologically-important range, the natural frequencies of certain in- and out-of-plane modes can be close to one another, or even identically repeated.

scholarly journals Seismic Protection of RC Buildings by Polymeric Infill Wall-Frame Interface

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1577
Author(s):  
Ahmet Tugrul Akyildiz ◽  
Alicja Kowalska-Koczwara ◽  
Łukasz Hojdys
Keyword(s):  
Three Dimensional ◽  
Mode Shapes ◽  
Dimensional Structure ◽  
Seismic Loads ◽  
Rc Buildings ◽  
Infill Wall ◽  
Infill Walls ◽  
Rc Frames ◽  
Out Of Plane ◽  
Real Size

This paper is aimed at investigating the usage of flexible joints in masonry infilled walls surrounded by reinforced concrete (RC) frames. For this purpose, a real-size specimen was numerically created and exposed to the seismic loads. In order to evaluate both in-plane and out-of-plane performances of the infill walls, the system was chosen as a box shaped three-dimensional structure. In total, three different one-story constructions, which have single bays in two perpendicular directions, were modeled. The first type is the bare-frame without the infill walls, which was determined as a reference system. The second and third types of buildings are conventional mortar joint and PolyUrethane Flexible Joint (PUFJ) implemented ones, respectively. The influence of these joints on the material level are investigated in detail. Furthermore, general building dynamic characteristics were extracted by means of acceleration and displacement results as well as frequency domain mode shapes. Analyses revealed that PUFJ implementation on such buildings has promising outcomes and helps to sustain structural stability against the detrimental effects of earthquakes.

Experiments and Analysis on Stability of the Sandwich Structures with Soft Core

2019 ◽  
Vol 19 (12) ◽  
pp. 1950159 ◽  
Author(s):  
Dongjian Zhang ◽  
Xitao Zheng ◽  
Chongzhe Wang ◽  
Zhen Wu
Keyword(s):  
Comparative Analysis ◽  
Transverse Shear ◽  
Three Dimensional ◽  
Sandwich Beam ◽  
Beam Element ◽  
Surface Boundary ◽  
Sandwich Beams ◽  
3D Fem ◽  
Surface Boundary Conditions ◽  
Three Dimensional Finite Element

In this paper, first a complete buckling experiment of the sandwich beams with the foam core is carried out, which includes the manufacturing of specimens and their experimental verification. Second, a refined sinusoidal zig-zag theory (RSZT) is established, which can describe the zig-zag effect during the in-plane compression of sandwich beam and accommodate the transverse shear free surface boundary conditions. Based on the established model combined with Hu–Washizu variational principle, a two-node beam element has been developed to address the buckling problem of the sandwich beams. Thus, the established beam element is able to accommodate interlaminar continuous conditions of transverse shear stress. Several examples have been investigated to validate the accuracy of the established method. The comparative analysis of the results including experimental data, the results acquired from three-dimensional finite element (3D-FEM) and diverse models has been made. Comparative analysis shows that the accurate buckling loads can be acquired from the established model. Nevertheless, other models discarding the continuous conditions of transverse stresses among the adjacent layers largely overestimate the critical loads.

Three-dimensional elasticity solution for sandwich beams/wide plates with orthotropic phases: The negative discriminant case

2011 ◽  
Vol 13 (6) ◽  
pp. 641-661 ◽  
Author(s):  
George A. Kardomateas ◽  
Catherine N. Phan
Keyword(s):  
Composite Laminates ◽  
Three Dimensional ◽  
Sandwich Beam ◽  
Isotropic Case ◽  
Isotropic Phase ◽  
Sandwich Beams ◽  
Elasticity Solution ◽  
Positive Real ◽  
Three Dimensional Elasticity ◽  
Positive Discriminant

In an earlier paper, Pagano (1969) [Pagano NJ. Exact solutions for composite laminates in cylindrical bending. J Compos. Mater. 1969; 3: 398–411] presented the three-dimensional elasticity solution for orthotropic beams (applicable also to sandwich beams) for the cases of: (1) a phase with positive discriminant of the qudratic characteristic equation, which is formed from the orthotropic material constants and further restricted to positive real roots and (2) an isotropic phase, which results in a zero discriminant. The roots in this case are all real, unequal, and positive (positive discriminant) or all real and equal (isotropic case). This purpose of this article is to present the corresponding solution for the cases of (1) negative discrimnant, in which case the two roots are complex conjugates and (2) positive discriminant but real negative roots. The case of negative discriminant is frequently encountered in sandwich construction, where the orthotropic core is stiffer in the transverse than the in-plane directions. Example problems with realistic materials are solved and compared with the classical and the first-order shear sandwich beam theories.

Analysis of Interface Deformation of Steel-Concrete-Steel Sandwich Beam

2012 ◽  
Vol 525-526 ◽  
pp. 357-360
Author(s):  
Pei Xiu Xia ◽  
Guang Ping Zou ◽  
Zhong Liang Chang
Keyword(s):  
Sandwich Beam ◽  
Analytical Models ◽  
Sandwich Beams ◽  
Interface Deformation ◽  
Simply Supported ◽  
Interface Slip ◽  
Steel Panels ◽  
Uniformly Distributed Loads ◽  
Relationship Of ◽  
The Relationship

The effect of the interface slip is neglected in most studies on calculating deflection of sandwich beams. By taking a simply supported sandwich beams under uniformly distributed loads as an example, simplified analytical models of the interface slip are established, and corresponding clculation formulas of interface slip between steel panels and concrete and section curvatures are derived. The formula for deflection of sandwich beams are then presented. This formula reflects the relationship of influence each other between the interface slip and deflection.

Conical SNA using fuzzy k-medoids based on user experience

2021 ◽  
pp. 002072092098849
Author(s):  
Poonam Rani ◽  
MPS Bhatia ◽  
Devendra K Tayal
Keyword(s):  
Social Networks ◽  
Social Network ◽  
User Experience ◽  
Three Dimensional ◽  
Experimental Results ◽  
Dynamic Parameters ◽  
Clustering Method ◽  
Cone Model ◽  
Intelligent Approach ◽  
Conical Model

The paper presents an intelligent approach for the comparison of social networks through a cone model by using the fuzzy k-medoids clustering method. It makes use of a geometrical three-dimensional conical model, which astutely represents the user experience views. It uses both the static as well as the dynamic parameters of social networks. In this, we propose an algorithm that investigates which social network is more fruitful. For the experimental results, the proposed work is employed on the data collected from students from different universities through the Google forms, where students are required to rate their experience of using different social networks on different scales.

Numerical and experimental investigation for enhancing the energy absorption capacity of the novel three-dimensional printed sandwich structures

2021 ◽  
pp. 146442072199749
Author(s):  
H Geramizadeh ◽  
S Dariushi ◽  
S Jedari Salami
Keyword(s):  
Energy Absorption ◽  
Sandwich Structures ◽  
Three Dimensional ◽  
Absorption Capacity ◽  
The Novel ◽  
Energy Absorption Capacity ◽  
Fused Deposition ◽  
Honeycomb Sandwich ◽  
Out Of Plane ◽  
Vertical Walls

The current study focuses on designing the optimal three-dimensional printed sandwich structures. The main goal is to improve the energy absorption capacity of the out-of-plane honeycomb sandwich beam. The novel Beta VI and Alpha VI were designed in order to achieve this aim. In the Beta VI, the connecting curves (splines) were used instead of the four diagonal walls, while the two vertical walls remained unchanged. The Alpha VI is a step forward on the Beta VI, which was promoted by filleting all angles among the vertical walls, created arcs, and face sheets. The two offered sandwich structures have not hitherto been provided in the literature. All models were designed and simulated by the CATIA and ABAQUS, respectively. The three-dimensional printer fabricated the samples by fused deposition modeling technique. The material properties were determined under tensile, compression, and three-point bending tests. The results are carried out by two methods based on experimental tests and finite element analyses that confirmed each other. The achievements provide novel insights into the determination of the adequate number of unit cells and demonstrate the energy absorption capacity of the Beta VI and Alpha VI are 23.7% and 53.9%, respectively, higher than the out-of-plane honeycomb sandwich structures.

scholarly journals In-Process Measurement of Three-Dimensional Deformations Based on Speckle Photography

2021 ◽  
Vol 11 (11) ◽  
pp. 4981
Author(s):  
Andreas Tausendfreund ◽  
Dirk Stöbener ◽  
Andreas Fischer
Keyword(s):  
Evaluation Method ◽  
Process Analysis ◽  
Plane Deformation ◽  
Three Dimensional ◽  
Machining Process ◽  
Image Correlation ◽  
Speckle Photography ◽  
Process Measurement ◽  
Out Of Plane ◽  
Plane Deformations

In the concept of the process signature, the relationship between a material load and the modification remaining in the workpiece is used to better understand and optimize manufacturing processes. The basic prerequisite for this is to be able to measure the loads occurring during the machining process in the form of mechanical deformations. Speckle photography is suitable for this in-process measurement task and is already used in a variety of ways for in-plane deformation measurements. The shortcoming of this fast and robust measurement technique based on image correlation techniques is that out-of-plane deformations in the direction of the measurement system cannot be detected and increases the measurement error of in-plane deformations. In this paper, we investigate a method that infers local out-of-plane motions of the workpiece surface from the decorrelation of speckle patterns and is thus able to reconstruct three-dimensional deformation fields. The implementation of the evaluation method enables a fast reconstruction of 3D deformation fields, so that the in-process capability remains given. First measurements in a deep rolling process show that dynamic deformations underneath the die can be captured and demonstrate the suitability of the speckle method for manufacturing process analysis.

scholarly journals Identification of Mode Shapes of a Composite Cylinder Using Convolutional Neural Networks

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2801
Author(s):  
Bartosz Miller ◽  
Leonard Ziemiański
Keyword(s):  
Neural Networks ◽  
Convolutional Neural Networks ◽  
Composite Structures ◽  
Three Dimensional ◽  
Mode Shapes ◽  
Identification Algorithm ◽  
Material Degradation ◽  
Local Material ◽  
Noisy Input ◽  
Shape Vector

The aim of the following paper is to discuss a newly developed approach for the identification of vibration mode shapes of multilayer composite structures. To overcome the limitations of the approaches based on image analysis (two-dimensional structures, high spatial resolution of mode shapes description), convolutional neural networks (CNNs) are applied to create a three-dimensional mode shapes identification algorithm with a significantly reduced number of mode shape vector coordinates. The CNN-based procedure is accurate, effective, and robust to noisy input data. The appearance of local damage is not an obstacle. The change of the material and the occurrence of local material degradation do not affect the accuracy of the method. Moreover, the application of the proposed identification method allows identifying the material degradation occurrence.

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