scholarly journals Thermal Inertia Characterization of Multilayer Lightweight Walls: Numerical Analysis and Experimental Validation

2021 ◽  
Vol 11 (11) ◽  
pp. 5008
Author(s):  
Juan José del Coz-Díaz ◽  
Felipe Pedro Álvarez-Rabanal ◽  
Mar Alonso-Martínez ◽  
Juan Enrique Martínez-Martínez
Keyword(s):  
Lightweight Concrete ◽  
Thermal Flux ◽  
Experimental Studies ◽  
Thermal Inertia ◽  
Transient State ◽  
Experimental Tests ◽  
Building Design ◽  
Experimental Methodology ◽  
Improve Energy Efficiency ◽  
Concrete Blocks

The thermal inertia properties of construction elements have gained a great deal of importance in building design over the last few years. Many investigations have shown that this is the key factor to improve energy efficiency and obtain optimal comfort conditions in buildings. However, experimental tests are expensive and time consuming and the development of new products requires shorter analysis times. In this sense, the goal of this research is to analyze the thermal behavior of a wall made up of lightweight concrete blocks covered with layers of insulating materials in steady- and transient-state conditions. For this, numerical and experimental studies were done, taking outdoor temperature and relative humidity as a function of time into account. Furthermore, multi-criteria optimization based on the design of the experimental methodology is used to minimize errors in thermal material properties and to understand the main parameters that influence the numerical simulation of thermal inertia. Numerical Finite Element Models (FEM) will take conduction, convection and radiation phenomena in the recesses of lightweight concrete blocks into account, as well as the film conditions established in the UNE-EN ISO 6946 standard. Finally, the numerical ISO-13786 standard and the experimental results are compared in terms of wall thermal transmittance, thermal flux, and temperature evolution, as well as the dynamic thermal inertia parameters, showing a good agreement in some cases, allowing builders, architects, and engineers to develop new construction elements in a short time with the new proposed methodology.

scholarly journals Bending and Shear Experimental Tests and Numerical Analysis of Composite Slabs Made Up of Lightweight Concrete

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
F. P. Alvarez Rabanal ◽  
J. Guerrero-Muñoz ◽  
M. Alonso-Martinez ◽  
J. E. Martinez-Martinez
Keyword(s):  
Numerical Simulations ◽  
Lightweight Concrete ◽  
Numerical Models ◽  
Experimental Studies ◽  
Experimental Tests ◽  
Isotropic Hardening ◽  
Structural Behaviour ◽  
Composite Slabs ◽  
The Coefficient Of Friction ◽  
Materials Used

The aim of this paper is to understand the structural behaviour of composite slabs. These composite slabs are made of steel and different kinds of concrete. The methodology used in this paper combines experimental studies with advanced techniques of numerical simulations. In this paper, four types of concrete were used in order to study their different structural strengths in composite slabs. The materials used were three lightweight concretes, a normal concrete, and a cold conformed steel deck which has embossments to increase the adherence between concrete and steel. Furthermore, two lengths of slabs were studied to compare structural behaviours between short and long slabs. m-k experimental tests were carried out to obtain the flexural behaviour of the composite slabs. These tests provide dimensionless coefficients to compare different sizes of slabs. Nonlinear numerical simulations were performed by means of the finite element method (FEM). Four different multilinear isotropic hardening laws were used to simulate the four concretes. Coulomb friction contact was used to model the coefficient of friction between steel and concrete. Finally, a chemical bond was included to consider sliding resistance in the contact surface between steel and concrete. Experimental and numerical results are in good agreement; therefore, numerical models can be used to improve and optimize lightweight composite slabs.

scholarly journals Design Corrections in Spanish Office Buildings to Improve Energy Efficiency in the Face of Climate Change

2020 ◽  
Vol 5 (12) ◽  
pp. 114
Author(s):  
José A. Orosa ◽  
Diego Vergara ◽  
Feliciano Fraguela ◽  
Pablo Fernández-Arias
Keyword(s):  
Climate Change ◽  
Energy Efficiency ◽  
Energy Consumption ◽  
Carbon Dioxide Emissions ◽  
Natural Ventilation ◽  
Thermal Inertia ◽  
Building Design ◽  
Wall Structure ◽  
Intergovernmental Panel ◽  
Improve Energy Efficiency

The majority of buildings in Europe are at present naturally ventilated and do not use heating or cooling equipment throughout the summer. However, this idea is changing and as a result heating ventilation air conditioning (HVAC) related energy consumption has been rising in the recent years. On the other hand, predictions published by the intergovernmental Panel on Climate Change (IPCC) indicate an annual warming rate ranging between 0.1 and 0.4 °C. In the present study, the ISO 13790:2011 standard has been employed to analyze the effect of building design corrections over the energy saving of a real building during its mean life and under climatic change predictions. In this sense, the effect of climate change, ventilation rate and its energetic and carbon dioxide emissions implications are obtained for the next 15 years. The results obtained indicate that an increment in the air changes by natural ventilation will be more effective than changing the wall structure and, in consequence, the thermal inertia. In particular, it was obtained that an increase of natural ventilation will always reduce the energy consumption and that this consumption will be lower with time due to an increment of an average outdoor air temperature. This modification will allow reduced cooling energy peak demands during the summer season and improve indoor ambiences in mild regions and the energy efficiency.

Experimental Studies Concerning the Semipermeable Membrane Separation Efficiency for 134Cs, 137Cs, 57Co, 58Co, 60Co, 54Mn in Liquid Radioactive Waste I. Treatment of secondary waste from POD decontamination procedure

2008 ◽  
Vol 59 (5) ◽  
Author(s):  
Mirela Dulama ◽  
Nicoleta Deneanu ◽  
Cristian Dulama ◽  
Margarit Pavelescu
Keyword(s):  
Membrane Separation ◽  
Separation Efficiency ◽  
Liquid Radioactive Waste ◽  
Experimental Studies ◽  
Experimental Tests ◽  
Suspended Solid ◽  
Process Efficiency ◽  
Active Charcoal ◽  
Precipitation Process ◽  
Pre Treatment

The paper presents the experimental tests concerning the treatment by membrane techniques of radioactive aqueous waste. Solutions, which have been treated by using the bench-scale installation, were radioactive simulated secondary wastes from the decontamination process with modified POD. Generally, an increasing of the retention is observed for most of the contaminants in the reverse osmosis experiments with pre-treatment steps. The main reason for taking a chemical treatment approach was to selectively remove soluble contaminants from the waste. In the optimization part of the precipitation step, several precipitation processes were compared. Based on this comparison, mixed [Fe(CN)6]4-/Al3+/Fe2+ was selected as a precipitation process applicable for precipitation of radionuclides and flocculation of suspended solid. Increased efficiencies for cesium radionuclides removal were obtained in natural zeolite adsorption pre-treatment stages and this was due to the fact that volcanic tuff used has a special affinity for this element. Usually, the addition of powdered active charcoal serves as an advanced purifying method used to remove organic compounds and residual radionuclides; thus by analyzing the experimental data (for POD wastes) one can observe a decreasing of about 50% for cobalt isotopes subsequently to the active charcoal adsorption.. The semipermeable membranes were used, which were prepared by the researchers from the Research Center for Macromolecular Materials and Membranes, Bucharest. The process efficiency was monitored by gamma spectrometry.

scholarly journals Experimental and Numerical Investigation on the Perforation Resistance of Double-Layered Metal Shield under High-Velocity Impact of Armor-Piercing Projectiles

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 626
Author(s):  
Riccardo Scazzosi ◽  
Marco Giglio ◽  
Andrea Manes
Keyword(s):  
High Strength Steel ◽  
Steel Plate ◽  
Experimental Studies ◽  
Practical Interest ◽  
High Strength ◽  
Experimental Tests ◽  
Element Model ◽  
Transportation Systems ◽  
Metal Shield ◽  
Softening Parameter

In the case of protection of transportation systems, the optimization of the shield is of practical interest to reduce the weight of such components and thus increase the payload or reduce the fuel consumption. As far as metal shields are concerned, some investigations based on numerical simulations showed that a multi-layered configuration made of layers of different metals could be a promising solution to reduce the weight of the shield. However, only a few experimental studies on this subject are available. The aim of this study is therefore to discuss whether or not a monolithic shield can be substituted by a double-layered configuration manufactured from two different metals and if such a configuration can guarantee the same perforation resistance at a lower weight. In order to answer this question, the performance of a ballistic shield constituted of a layer of high-strength steel and a layer of an aluminum alloy impacted by an armor piercing projectile was investigated in experimental tests. Furthermore, an axisymmetric finite element model was developed. The effect of the strain rate hardening parameter C and the thermal softening parameter m of the Johnson–Cook constitutive model was investigated. The numerical model was used to understand the perforation process and the energy dissipation mechanism inside the target. It was found that if the high-strength steel plate is used as a front layer, the specific ballistic energy increases by 54% with respect to the monolithic high-strength steel plate. On the other hand, the specific ballistic energy decreases if the aluminum plate is used as the front layer.

River Soil & Sand Solidified Blocks as Ballast in Beach Protection

2013 ◽  
Vol 779-780 ◽  
pp. 323-326 ◽  
Author(s):  
Jing Min Mao ◽  
Da Feng Gao
Keyword(s):  
Yangtze River ◽  
Setting Time ◽  
Experimental Studies ◽  
Curing Agent ◽  
The Yangtze River ◽  
Environment Protection ◽  
Time Stability ◽  
Alternative Materials ◽  
Concrete Blocks ◽  
Protection Engineering

This paper deals with the feasibility of beach protection project alternative materials - the Yangtze River soil and sand, applies PCSB curing agent to solidify it and to produce beach protection blocks. Experimental studies on the performance of strength, setting time, stability and anti-erosion have been carried out to inquire into the regularity of solidification. Using soil and sand curing blocks instead of concrete blocks in the application of Yangtze River beach protection engineering has advantages of technology, economy and environment protection etc.

scholarly journals Numerical and experimental evaluation of masonry prisms by finite element method

2017 ◽  
Vol 10 (2) ◽  
pp. 477-508 ◽  
Author(s):  
C. F.R. SANTOS ◽  
R. C. S. S. ALVARENGA ◽  
J. C. L. RIBEIRO ◽  
L. O CASTRO ◽  
R. M. SILVA ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element Method ◽  
High Strength Concrete ◽  
Numerical Models ◽  
High Strength ◽  
Experimental Tests ◽  
Experimental Results ◽  
Concrete Blocks ◽  
Micro Modeling ◽  
Modeling Strategy

Abstract This work developed experimental tests and numerical models able to represent the mechanical behavior of prisms made of ordinary and high strength concrete blocks. Experimental tests of prisms were performed and a detailed micro-modeling strategy was adopted for numerical analysis. In this modeling technique, each material (block and mortar) was represented by its own mechanical properties. The validation of numerical models was based on experimental results. It was found that the obtained numerical values of compressive strength and modulus of elasticity differ by 5% from the experimentally observed values. Moreover, mechanisms responsible for the rupture of the prisms were evaluated and compared to the behaviors observed in the tests and those described in the literature. Through experimental results it is possible to conclude that the numerical models have been able to represent both the mechanical properties and the mechanisms responsible for failure.

Mechanical Properties of Various Models of Interlocking Concrete Blocks under In-Plane and Out-of-Plane Loads

2021 ◽  
Vol 881 ◽  
pp. 149-156
Author(s):  
Mochamad Teguh ◽  
Novi Rahmayanti ◽  
Zakki Rizal
Keyword(s):  
Mechanical Properties ◽  
Building Material ◽  
Experimental Tests ◽  
Concrete Block ◽  
Masonry Wall ◽  
Masonry Walls ◽  
Plane Shear ◽  
Out Of Plane ◽  
Concrete Blocks ◽  
Local Materials

Building material innovations in various interlocking concrete block masonry from local materials to withstand lateral earthquake forces is an exciting issue in masonry wall research. The block hook has an advantage in the interlocking system's invention to withstand loads in the in-plane and out-of-plane orientations commonly required by the masonry walls against earthquake forces. Reviews of the investigation of in-plane and out-of-plane masonry walls have rarely been found in previous studies. In this paper, the results of a series of experimental tests with different interlocking models in resisting the simultaneous in-plane shear and out-of-plane bending actions on concrete blocks are presented. This paper presents a research investigation of various interlocking concrete blocks' mechanical properties with different hook thicknesses. Discussion of the trends mentioned above and their implications towards interlocking concrete block mechanical properties is provided.

A NEW GEARBOX FAULT DIAGNOSIS METHOD BASED ON LUCY–RICHARDSON DECONVOLUTION

2015 ◽  
Vol 39 (3) ◽  
pp. 593-603
Author(s):  
Xinghui Zhang ◽  
Jianshe Kang ◽  
Hongzhi Teng ◽  
Jianmin Zhao
Keyword(s):  
Fault Diagnosis ◽  
Experimental Studies ◽  
Experimental Tests ◽  
Rolling Element Bearings ◽  
Envelope Analysis ◽  
Rolling Element ◽  
Negative Effect ◽  
Diagnosis Method ◽  
Good Identification ◽  
Incipient Fault Diagnosis

Gear and bearing faults are the main causes of gearbox failure. Till now, incipient fault diagnosis of these two components has been a problem and needs further research. In this context, it is found that Lucy–Richardson deconvolution (LRD) proved to be an excellent tool to enhance fault diagnosis in rolling element bearings and gears. LRD’s good identification capabilities of fault frequencies are presented which outperform envelope analysis. This is very critical for early fault diagnosis. The case studies were carried out to evaluate the effectiveness of the proposed method. The results of simulated and experimental studies show that LRD is efficient in alleviating the negative effect of noise and transmission path. The results of simulation and experimental tests demonstrated outperformance of LRD compared to classical envelope analysis for fault diagnosis in rolling element bearings and gears, especially when it is applied to the processing of signals with strong background noise.

scholarly journals Research the hardness of polymer materials after turning

2020 ◽  
Vol 329 ◽  
pp. 03041
Author(s):  
Oleg Erenkov ◽  
Elena Yavorskaya
Keyword(s):  
Experimental Studies ◽  
Polymer Materials ◽  
Experimental Methodology ◽  
Elastic Aftereffect

The paper presents the results of experimental studies to determine the hardness of the treated surface depending on the conditions and machining type of workpieces made of textolite, caprolon and fluoroplastic. The experimental methodology and explanation of the reasons for changing the hardness of the treated surface for the investigated variants of machining the materials are under study. The results of studying the influence of the phenomenon of elastic aftereffect of the polymer materials after workpieces machining are obtained.

scholarly journals A Narrative Review of Libidibia ferrea: Botanical Aspects, Ethnopharmacological Properties, Phytochemical Characteristics, Toxicity, and Experimental Tests

2021 ◽  
pp. 16-30
Author(s):  
Nayanne C. O. da S. Almeida ◽  
Silvania da C. Furtado ◽  
José F. M. Barcellos
Keyword(s):  
Urban Areas ◽  
Folk Medicine ◽  
Experimental Studies ◽  
Experimental Tests ◽  
Stem Bark ◽  
Experimental Models ◽  
Narrative Review ◽  
In Vivo Models ◽  
Methodological Guidelines

Introduction: Jucá or pau-ferro (Libidibia ferrea) is an arboreal plant from the Fabaceae family. It is commonly used in traditional medicine in the treatment of various diseases, including inflammatory process. Aims: The objective of this narrative review is to present botanical aspects, ethnopharmacological properties, phytochemical characteristics, toxicity highlighting, and experimental models with L. ferrea. Results: Botanical Aspects: Jucá has several uses such as in landscaping (stem and canopy), in arborization of urban areas. Ethnopharmacological Properties: It is used in the treatment of various diseases such as diabetes, flu, asthma and, inflammatory processes of which different parts are used (root, stem bark, leaves, fruits, seeds). Phytochemical Characteristics: Phenolic compounds, fatty acids, and terpenoids are among the compounds monthly used. Toxicity: In vivo models have been used to verify toxicity and in most studies the plant presented no toxicity in its use. Experimental studies: Animals, such as mice, dogs, rats, etc. and different models of studies to analyze the action of the plant were used. Conclusions: Such low toxicity, associated with its widespread use in folk medicine and its various effects demonstrated in the studies included in this Review have corroborated for the continuity of the research with L. ferrea. New studies, however, ought to follow methodological guidelines, such as the Animal Research: reporting in vivo Experiments (ARRIVE) so that, a methodological design secures more homogeneous studies capable of quantifying the actual size of the effect in the plant may have in clinical studies.  

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