Study of Thin Sandwich Beams With Steel Faces and Perforated Polymer Core in Bending Loading: Experiments and Simulations

2010 ◽  
Vol 78 (1) ◽  
Author(s):  
P. Lhuissier ◽  
J.-P. Masse ◽  
L. Salvo ◽  
Y. Brechet
Keyword(s):  
Numerical Simulations ◽  
Failure Modes ◽  
Numerical Models ◽  
Large Strain ◽  
Porous Polymer ◽  
Analytical Models ◽  
Sandwich Beams ◽  
The Core ◽  
Set Up ◽  
Bending Loading

The mechanical behavior of thin sandwich beams with steel faces and porous polymer core have been investigated using quasistatic four-points bending. Classic sandwich models predicting the behavior and the failure modes are improved to fit the particular configuration of the structure. Numerical simulations were set up in order to investigate damage at large strain. Macroscopic results are compared with analytical models and numerical simulations. Two numerical models of the core allowed confrontation of local behavior with experiments. Criteria for localization and damaging depending on core architecture are proposed.

Failure and Deformation Modes of Sandwich Beams under Quasi-Static Loading

2010 ◽  
Vol 29-32 ◽  
pp. 84-88
Author(s):  
Lin Jing ◽  
Zhi Hua Wang ◽  
Long Mao Zhao
Keyword(s):  
Aluminum Foam ◽  
Failure Modes ◽  
Experimental Results ◽  
Sandwich Beams ◽  
Foam Material ◽  
Deformation And Failure ◽  
Structure Response ◽  
The Core ◽  
Bottom Face ◽  
Deformation Modes

In this paper the structure response of quasi-statically loaded sandwich beams made of aluminum skins with open-cell aluminum foam cores is investigated experimentally. The experimental programme was designed to investigate the deformation and failure modes of sandwich beams, so a large number of experiments have been conducted, and the experimental results are reported and discussed systematically. It is found that sandwich beams under quasi-static punching loads can fail in several modes: face yield, face wrinkling, core shear, the bottom face fracture and interfacial failure between the core and the faces. Moreover, the effects of face thickness, cell size of foam material on the failure and deformation modes were discussed. The experimental results are of worth to optimum design of cellular metallic sandwich structures.

Evaluation of numerical pounding models with experimental validation

2013 ◽  
Vol 46 (3) ◽  
pp. 117-130 ◽  
Author(s):  
S. Khatiwada ◽  
N. Chouw ◽  
J.W. Butterworth
Keyword(s):  
Numerical Simulations ◽  
Numerical Models ◽  
Experimental Studies ◽  
Viscoelastic Model ◽  
The Other ◽  
Analytical Models ◽  
Seismic Gap ◽  
Shake Table ◽  
Linear Viscoelastic ◽  
Linear Viscoelastic Model

Pounding damage in major earthquakes has been observed frequently in the form of aesthetic, minor or major structural cracks and collapse of buildings. These observations have attracted many numerical and experimental studies that led to analytical models for simulating seismic pounding. This study considers pounding between two steel portal frames without a seismic gap. The first frame has a constant natural period while the second frame has variable stiffness and mass values. Five different ground motions are applied to eight combinations of adjacent frames using a shake table. Numerical simulations for the same configurations are carried out with five pounding force models, viz. linear viscoelastic model, modified linear viscoelastic model, nonlinear viscoelastic model, Hertzdamp model and modified Hertzdamp model. The contact element stiffness and coefficient of restitution for numerical models are determined experimentally. The amplification of maximum displacement of the first frame predicted by the numerical simulations is compared with the shake table results. It was found that the Hertzdamp model always overestimated the responses while the other four models also frequently overestimated the amplifications. The predictions from the four models were not significantly different. Since the linear viscoelastic model requires substantially less computation, compared with the other models this model is more suitable for numerical modelling of pounding responses. However, more study is required to refine the numerical models before building pounding can be modelled with enough confidence.

scholarly journals Experimental Study of Load-Bearing Cold-Formed Steel Walls Exposed to Realistic Design Fires

2014 ◽  
Vol 5 (4) ◽  
pp. 291-330 ◽  
Author(s):  
Anthony Ariyanayagam ◽  
Mahen Mahendran
Keyword(s):  
Failure Modes ◽  
Parametric Design ◽  
Numerical Models ◽  
Test Procedure ◽  
Natural Fire ◽  
Deformation Curves ◽  
Design Fire ◽  
Wall Panels ◽  
Measured Time ◽  
Set Up

This paper presents the details of full scale fire tests of LSF wall panels conducted using realistic fire time-temperature curves. Tests included eight LSF wall specimens of various configurations exposed to both parametric design and natural fire curves. Details of the fire test set-up, test procedure and the results including the measured time-temperature and deformation curves of LSF wall panels are presented along with wall stud failure modes and times. This paper also compares the structural and thermal behavioural characteristics of LSF wall studs with those based on the standard time-temperature curve. Finally, the stud failure times and temperatures are summarized for both standard and realistic design fire curves. This study provides the necessary test data to validate the numerical models of LSF wall panels and to undertake a detailed study into the structural and thermal performance of LSF wall panels exposed to realistic design fire curves.

scholarly journals Nonlinear numerical simulation of punching shear behaviour of reinforced concrete flat slabs with shear-heads

2019 ◽  
Author(s):  
D.V. Bompa ◽  
A.Y. Elghazouli
Keyword(s):  
Reinforced Concrete ◽  
Failure Modes ◽  
Numerical Models ◽  
Three Dimensional ◽  
Structural Response ◽  
Analytical Models ◽  
Shear Behaviour ◽  
Flat Slabs ◽  
Modes Of Failure ◽  
Concrete Damage

This paper examines the structural response of reinforced concrete flat slabs, provided with fully-embedded shear-heads, through detailed three-dimensional nonlinear numerical simulations and parametric assessments using concrete damage plasticity models. Validations of the adopted nonlinear finite element procedures are carried out against experimental results from three test series. After gaining confidence in the ability of the numerical models to predict closely the full inelastic response and failure modes, numerical investigations are carried out in order to examine the influence of key material and geometric parameters. The results of these numerical assessments enable the identification of three modes of failure as a function of the interaction between the shear-head and surrounding concrete. Based on the findings, coupled with results from previous studies, analytical models are proposed for predicting the rotational response as well as the ultimate strength of such slab systems. Practical recommendations are also provided for the design of shear-heads in RC slabs, including the embedment length and section size. The analytical expressions proposed in this paper, based on a wide-ranging parametric assessment, are shown to offer a more reliable design approach in comparison with existing methods for all types of shear-heads, and are suitable for direct practical application.

scholarly journals Experimental Investigation of Instabilities on Different Scales in Compressive Fatigue Testing of Composites

2021 ◽  
Vol 5 (4) ◽  
pp. 114
Author(s):  
Andreas Baumann ◽  
Joachim Hausmann
Keyword(s):  
Failure Modes ◽  
Fatigue Testing ◽  
Analytical Models ◽  
Fiber Reinforced ◽  
Continuous Fiber ◽  
Creep Tests ◽  
Test Set ◽  
Fiber Reinforced Materials ◽  
Set Up ◽  
Reinforced Materials

Compression testing of continuous fiber reinforced materials is challenging, because a great number of competing failure modes and instabilities on different length scales have to be considered. In comparison to tensile testing, the results are more affected by the chosen test set-up. Effects introduced by the test set-up as well as the type of damage in continuous fiber reinforced materials are mainly investigated for quasi-static loading. This is not the case for cyclic compression loading. Neither standardized methods nor a great deal of literature for reference exists. The aim of this work is to increase the understanding by analyzing the potential effects the set-up in fatigue loading might have on the damage for two common testing strategies by fatigue tests, load increase creep tests and supplementary analytical models. The results show that damage modes can be altered by the testing strategy for the investigated woven glass fiber reinforced polyamide 6. The tools both experimentally and analytically provide the basis to choose the correct set-up in future investigations.

Thermal Management Strategies for Embedded Electronic Components of Wearable Computers

1999 ◽  
Vol 122 (2) ◽  
pp. 98-106 ◽  
Author(s):  
Eric Egan ◽  
Cristina H. Amon
Keyword(s):  
Numerical Simulations ◽  
Polymer Composite ◽  
Numerical Models ◽  
The Body ◽  
Thermal Design ◽  
Analytical Models ◽  
Conductive Heat ◽  
Wearable Computer ◽  
Computer Design ◽  
Wearable Computers

Wearable computers are rugged, portable computers that can be comfortably worn on the body and easily operated for maintenance applications. The recently developed process of Shape Deposition Manufacturing has created the opportunity to embed the electronics of wearable computers in a polymer composite substrate. As both a protective outer case and a conductive heat dissipating medium, the substrate satisfies two basic constraints of wearable computer design: ruggedness and cooling efficiency. One such application of embedded electronics is the VuMan3R, a wearable computer designed and manufactured at Carnegie Mellon University for aircraft maintenance. This paper combines finite element numerical simulations, physical experimentation, and analytical models to understand the thermal phenomena of embedded electronic design and to explore the thermal design space. Numerical models ascertain the effect of heat spreaders and polymer composite substrates on the thermal performance, while physical experimentation of an embedded electronic artifact ensures the accuracy of the numerical simulations and the practicality of the thermal design. Analytical models using thermal resistance networks predict the heat flow paths within the embedded electronic artifact as well as the role of conductive fillers used in polymer composites. [S1043-7398(00)00102-X]

Experimental and Numerical Study of Solidification in Constant and Oscillating Temperature Gradients

2003 ◽  
Author(s):  
Y. Shu ◽  
B. Q. Li
Keyword(s):  
Numerical Simulations ◽  
Numerical Study ◽  
Numerical Models ◽  
Experimental System ◽  
Temperature Gradients ◽  
Working Fluid ◽  
Set Up ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Planar Solidification

Transient finite element models are developed to describe solidification of materials in constant and oscillating temperature gradients. Both moving grids and fixed methods are applied, with the former intended to model the near-planar solidification front, while the latter for complex solid-liquid interface morphology. Extensive numerical simulations are conducted for various configurations. To validate the model predictions, an experimental system has been set up with Succinonitrile (SCN) as a working fluid. The melt flows and solidification are measured using a laser PIV system. The measurements are compared well with numerical results obtained from the numerical models. Reasonably good agreement between the experimental measurements and numerical simulations is obtained.

Core Failure Modes in Composite Sandwich Beams

2001 ◽  
Author(s):  
Isaac M. Daniel ◽  
Emmanuel E. Gdoutos ◽  
Jandro L. Abot ◽  
Kuang-An Wang
Keyword(s):  
Failure Modes ◽  
Sandwich Beams ◽  
Deformation And Failure ◽  
Balsa Wood ◽  
Composite Sandwich ◽  
The Core ◽  
Aluminum Honeycomb ◽  
Failure Loads ◽  
Materials Failure ◽  
Core Materials

Abstract Core failure modes were studied in composite sandwich beams under three-point bending and in cantilever beams under end loading. The beams consisted of unidirectional carbon/epoxy face sheets and a variety of core materials, including aluminum honeycomb, PVC closed-cell foams, polyurethane foam and balsa wood. The constituent materials were fully characterized and in the case of the core materials, failure envelopes were developed for biaxial states of stress. Deformation and failure mechanisms were studied experimentally by means of moiré gratings and birefringent coatings. Results were obtained for stress (strain) distributions in the linear and nonlinear/plastic range of the core, critical failure loads and their dependence on geometrical dimensions, material parameters and loading conditions.

Predicting Hoop Tendon Behaviour in Pre-Stressed Concrete Containment Vessel

2004 ◽  
Vol 1-2 ◽  
pp. 251-260 ◽  
Author(s):  
Nawal K. Prinja ◽  
Michael F. Hessheimer ◽  
Robert Dameron
Keyword(s):  
Failure Modes ◽  
Numerical Models ◽  
Limit Load ◽  
Structural Features ◽  
Analytical Models ◽  
Limit Loads ◽  
Containment Vessel ◽  
International Round ◽  
Pressurisation Test ◽  
Design Pressure

This paper is based on the experimental and numerical analysis work carried out as part of an international round robin aimed to predict the limit load of the ¼ scale Pre-stressed Concrete Containment Vessel (PCCV) which was tested at Sandia National Laboratories (SNL) in USA. The design pressure, Pd, for the PCCV was 0.39MPa. Pressurisation test was conducted causing global collapse of the PCCV structure, which occurred at the pressure of 1.423MPa (3.65 Pd). Displacements, loads and strains were monitored at 55 standard locations giving a unique opportunity to assess the accuracy and reliability in predicting failure modes and limit loads of PCCV structures. To simulate the inelastic response of the structure with extensive concrete cracking requires specialist numerical models and detailed geometric representation of the main structural features. One of the most important structural features was the prestressed hoop tendon system. The paper presents a brief explanation of the test, the instrumentation used to monitor the tendon behaviour and describes the analytical models employed to predict the tendon behaviour.

scholarly journals Numerical Study on Strength and Failure Behavior of Rock with Composite Defects under Uniaxial Compression

Energies ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4418
Author(s):  
Xiaofei Wang ◽  
Zhiguo Xia ◽  
Peng Li ◽  
Hongning Liu
Keyword(s):  
Numerical Simulations ◽  
Uniaxial Compression ◽  
Failure Modes ◽  
Numerical Study ◽  
Numerical Models ◽  
Displacement Vector ◽  
Surrounding Rock ◽  
Failure Behavior ◽  
Underground Engineering ◽  
Combined Defects

The cracks and holes in underground engineering are the critical factors that cause the instability of the surrounding rock. It is helpful to control the stability of surrounding rock to study the samples with combined defects of cracks and holes. In this study, PFC 2D is used to analyze the numerical models. Seven combined models of single circular hole and double cracks with different angles are established, and the fracture angle varies from 0° to 90° with an interval of 15°. First, uniaxial compression experiments and numerical simulations are carried out in the 0° defect combination model, and the microscopic parameters of PFC 2D are determined. Then, the numerical simulations of seven defect models under uniaxial compression are carried out, and the crack development law and acoustic emission characteristics of different defect combination models are studied. The failure modes, mechanical behavior, and stress states are studied. The displacement vector distributions of different defect combination models are analyzed; it is found that there are three main types of macro cracks in the defect combination samples. The results show that the combined defects reduce the strength of the model. Meanwhile, the distributions of the stress and displacement are changed by the cracks with different angles in the defective models.

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