Floor Panels Research Articles

Impact Strength of Laminated Floor Panel from Kenaf<i> (Hibiscus cannabinus)</i> High Density Fibreboard

This study provides a better understanding of the effect of density and thickness on impact strength of laminated floor panel from Kenaf high density fibreboard (KHDF). The objective of this study was therefore to determine the role of density and thickness on the impact strength of laminated floor panel. Laminated floor panels consisted of high density fibreboard (HDF) as core and decorative paper as surface layer and backing. Kenaf bast fibres were used for HDF with three different densities (850, 960 and 1000 kg/m3) with thickness of 8mm and 12mm for each panel. Energy (J) value was evaluated to determine the impact strength of all various floor panels. It was found that thickness has affected statistically on impact strength while there was no significantly difference existed on density of laminated floor panel on impact strength.

Adhesively bonded connections between composite sandwich floor panels for building rehabilitation

A connection system between adjacent sandwich panels for use in building floor rehabilitation, consisting of an adhesively (epoxy) bonded Z-joint, is proposed and studied. Experimental and numerical investigations were carried out to assess the joints’ behaviour under vertical loads, their effect on the overall mechanical response of the sandwich floor panels, and the stress distributions within the various panel components. Their behaviour along the transverse and longitudinal (main span) directions was studied for panels made of glass-fibre reinforced polymer (GFRP) faces and two types of cores: polyurethane (PUR) foam and balsa wood. The joints’ failure along the transverse direction occurred in the GFRP elements due to excessive through-thickness tensile stresses – failure in the adhesive layer was not observed. In the longitudinal direction, joint failure did not occur. The developed FE models were able to simulate the behaviour of the connections and jointed panels, providing reasonably accurate predictions for the deformations and failure modes experimentally observed. The joints significantly increased the panels’ shear stiffness, but showed limited influence on their bending stiffness. Although the flexural stiffness of the PUR foam and balsa wood cored panels was similar, the balsa wood core absorbed a significantly higher portion of shear force.

Optimization Of Parameters Of Heating Elements For Floor Panel Of Piglets Resting Places

The article deals with problem solving of mathematical physics using the method of separation of variables optimizing heating element – optimizing water tube parameters (tube material, radius, insulation thickness, choosing appropriate surrounding environment). For ensuring piglets comfort, concrete floor panels heated by electric current or hot water are used. If an electro-heated cable in the panels body is placed, than amount of heat conducted from the cable is the same along all the length of the cable. If hot water circulating through tube is used, than amount of heat energy taken off the heater decreases along its length. The aim of the research is to create the mathematical model of a water tube, were water temperature is gradually decreasing. This model is needed to make precise calculations of the heating panel for piglets, to ensure equal temperature distribution over the upper surface of the panel, taking into account mathematically calculated temperature decrease of the heat source.

Vibro-acoustic analysis of a coach platform under random excitation

Vibro-acoustic analysis of a rail vehicle cabin is presented in this paper. Vehicle is modeled by an air cavity coupled to a flexible floor panel. Analytical procedure is employed to predict the structural-borne noise in the vehicle model generated by random excitation of the panel. In this study, natural frequencies of the coupled system are obtained and then the sound pressure field inside the cavity is analytically determined. In order to find dynamic responses of the coupled system in the time domain, Durbin's numerical Laplace transform inversion algorithm is employed. Convergence of the algorithm is verified and eventually a parametric study is carried out to investigate the effects of rail irregularity and vehicle speed on the time and frequency responses.

Optimisation of the structural modes of automotive-type panels using line stiffeners and point masses to achieve weak acoustic radiation

In this paper, an optimisation method is presented that turns the structural modes of an automotive-type panel into weak acoustic radiators. The advantage of the proposed method is that the optimum design does not depend upon a specific excitation mechanism. Hence, the optimised panel can be used in the early stages of vehicle product design when specific knowledge about the excitation forces is not available. In the proposed method the boundary conditions of the panel are specified such that the panel can be considered in isolation from the rest of the structure. The optimisation of the structural modes of the panel is then achieved by placing a number of constraint masses and stiffeners of optimum size and weight at optimum locations on the plate. Firstly, a theoretical model of a simply-supported plate is developed that takes into account the constraints at arbitrary positions and orientations. Then a genetic algorithm is used to minimise the sound power radiated by different modes on the plate by finding the optimum design for the constraints. Secondly, the use of added masses and stiffeners is then applied to a floor panel of a simplified model of a vehicle body structure in order to reduce the radiated sound. Predicted and experimental results of the radiated sound power from a reference flat panel and from various optimised panel designs are presented to illustrate the effectiveness of the optimised designs in reducing radiated sound from the structure. A combination of masses and stiffeners is shown to be an effective way of constructing weakly radiating structural modes on the panel.

The Experimental Research on the Heating and Cooling Performance of Light Floor Radiant Panels

The steady state and dynamic performance of light radiant floor panels under heating and cooling conditions are studied in this paper by experiments. The surface temperature, the heating and cooling capacities are measured under different water supply temperature when the temperature of the room is stable. Through the tests, the heating and cooling capacities at different water supply temperature were obtained under steady conditions. For example, when the water supply temperature is 33°C, the heating capacity of the panel is about 76W and the data measured in the test is 75.9. The time constant of the light floor radiant panel is about 30min and is much smaller than that of traditional concrete floor.

Optimization Analysis on Storage Tank Volume in Solar Heating System

Based on the analysis of the storage and exothermic process of the storage tank, the energy balance equation was established, and discussed the relationship between storage tank volume and storage temperature difference, as well as that between the tank volume and the max heat storage. The average temperature of the tank and the auxiliary heat added for the system of a typical architecture in Xi’an during the heating season were simulated by TRNSYS. The paper discussed the operating conditions with changing the combination of systems and storage temperature difference, and found that the heat storage time of the tank is great different from the solar radiation time. SHS prefers floor panel heating with lower temperature and the thermal collector form that can ensure storage temperature range of 15̊C. Then it gives out the recommended value of required storage tank volume for a unit area of collector.

Analysis of Local Vibration for High-Speed Railway Bridge Based on Finite Element Method

Based on the theory of vehicle track coupling dynamics, the local vibration of the high-speed railway box girder is analyzed by the Finite Element Method and the model is simulated with the solid elements. Through the study of vibration characteristics of the selected 6 sensitive points, the local vibrations in different parts of the box girder are figured out. It is compared the response of the time domain and frequency domain in different parts of the cross section on different train speeds. Furthermore, the influence of track irregularity of local vibration response is analyzed. The results show that the track irregularity is the main factor causing local vibration. At last, the effects of local vibration on the boundary conditions are discussed. The response of top panel, floor panel and web panel were different and the flange panel was similar between the simple supported beam and the fixed beam.

Thermal performance of a radiant floor heating system with different heat storage materials and heating pipes

Experiments were carried out to investigate the performance of a low-temperature radiant floor heating system with different heat storage materials (sand and phase change material) and heating pipes (polyethylene coils and capillary mat) in the floor structure of a test room. Detailed temperatures in both floor structural layers and the air of the room were measured for four different combinations of these thermal mass and heating pipes during charge and discharge operations. The results showed that the floor structure with capillary mat provides more uniform temperature profile in vertical direction of the test room and needs much shorter time (nearly half) to attain the same room temperature than the cases with polyethylene (PE) coils during the charging process. Also, after the heat source was closed, the floor structures using phase change material (PCM) as thermal mass release heat about 2 times longer than the cases using sand. A CFD simulation is also performed which confirms the measured data during the charging and discharging processes. The results indicate the advantages of using PCM – capillary mat combination for low – temperature floor panel typical of solar – hot – water heating system.

THE PRESENT AND FUTURE PROSPECTS OF FRICTION STIR WELDING IN AERONAUTICS

Since its invention friction stir welding as a solid state joining method was considered primarily for aluminium alloys in the aerospace industry. Years of intense research and development were necessary to introduce the process for fabrication of aerospace components. It was necessary to accumulate sufficient information about process parameters, tooling and machinery for process specification, certification and design allowables. Friction stir welding was first used in space vehicles and in military aircraft, later it was used in civil aviation. Aircraft manufacturers such as Boeing, Airbus, and Embraer use this technique for components such as floor panels, fuselage panels, and wing ribs among others. This process allows for the introduction of new structural solutions in the same way that the development of advanced alloys also permits similar advances.

Meshless analysis of piezoelectric sensor embedded in composite floor panel

Piezoelectric materials are the key element in various sensors and sensory devices used in industry and research. In this article, we use the meshless local Petrov–Galerkin method to analyze a three-dimensional piezoelectric sensor that is embedded in a composite floor panel. Temporal variation of panel deformation is determined analytically and then prescribed as a boundary condition for the sensor. In the proposed formulation, quasi-static governing equations for the electric field and elastodynamic equations for mechanical fields are coupled together. Local integral equations are derived from the local weak form of the governing equations, using a Heaviside step function as the test function. Nodal points are distributed in the analyzed domain, and each node is the center of a small subdomain of spherical shape. The spatial variations of the displacement and electric potential are approximated by the moving least squares scheme. A system of ordinary differential equations is obtained after evaluation of all spatial integrals. The Houbolt finite-difference scheme is applied to solve this system of ordinary differential equations as a time-stepping method. The temporal variation of the induced electric field is finally obtained. It is shown that significant peak amplitudes of the electric field are detected at the top of the sensor.

The use of ducts to improve the control of supply air temperature rise in UFAD systems: CFD and lab study

Cool supply air flowing through the underfloor plenum is exposed to heat gain from both the concrete slab (conducted from the warm return air on the adjacent floor below the slab) and the raised floor panels (conducted from the warmer room above). The magnitude of this heat gain can be quite high, resulting in undesirable loss of control of the supply air temperature from the plenum into the occupied space. These warmer supply air temperatures can make it more difficult to maintain comfort in the occupied space (without increasing airflow rates), particularly in perimeter zones where cooling loads reach their highest levels. How to predict plenum thermal performance is one of the key design issues facing practicing engineers – evidence from completed projects indicates that excessive temperature rise in the plenum can be a problem.One of the recommended strategies for addressing temperature rise in UFAD systems is the use of ductwork (flexible or rigid) within the underfloor plenum to deliver cool air preferentially to perimeter zones or other critical areas of high cooling demand.Several experiments were carried out in a full-scale underfloor plenum test facility, in order to characterize all the phenomena that take place in an underfloor plenum equipped with a fabric or metal duct. Experimental data were collected for validation of a computational fluid dynamics (CFD) model of the plenum. This paper describes the first part of a more comprehensive work, whose aim is to use the validated CFD plenum model to conduct simulations of a broader range of plenum design and operational parameters. This work proves that using ductwork within the underfloor plenum reduce the temperature rise in the plenum.

Damping materials for floor panels

This paper describes the history of the development of typical damping materials for automotive floor panels from the introduction of asphalt sheet in Japan in 1963 until the present, as well as recent trends in the use of such materials. Technical developments in damping materials can be divided into the following four stages: (1) Noise reduction was attained by the effect of mass. (2) Elasticity was increased to improve the damping performance. (3) Constraining layers were added in the material (also to improve damping). (4) Weight reduction is being attempted; this is where the current research effort is being directed. A description is given of a resin constrained multi–layer–type damping material which maintains the same processability on the production line as is seen in conventional materials, while the damping performance is markedly improved.

Optimization of PCM embedded in a floor panel developed for thermal management of the lightweight envelope of buildings

Implementation of phase change materials (PCMs) into building components allows their thermal performance to be enhanced, reducing indoor temperature fluctuations and improving the occupant comfort. A practical problem to solve is the possibility of leakage when the PCM is under the liquid state. In this study, a new component using PCMs is described. This component derives from an existing slab having cylindrical cavities which is used in floors/ceilings. The cavities are filled with a polymer–paraffin composite and leaks are avoided, due to, both the use of the composite and the insertion inside cavities.This study is based on numerical simulations whose results are compared to experimental ones with the same boundary conditions in order to validate the model. The PCM was introduced inside the cavities with an annular repartition and different percentages. A new indicator was introduced (PCM activity) that allows an evaluation of the amount of PCM to be used in such a component. With this indicator the optimal percentage of PCM has been determined.

Multi Response Optimization of Drilling Parameters during Drilling of Particle Board Using Grey Relational Analysis

Particle board serves numerous functions such as cabinetry, tabletops, shelving, wall & floor panels, etc. Though Particle boards are much cheaper compared to solid wood, machining the material by optimizing the process parameters is a big challenge. Drilling is the major operation during final assembly of particle board, where fasteners are used to join together to bring final shape to the product. In this paper, the operation parameters such as speed, feed, drill diameter has been considered during drilling operation performed on Particle board and the output responses-surface roughness of the drilled hole and the Thrust force acting on the board during drilling are measured. Good surface finish of the hole ensures reduction of localised stresses around the hole due to fastening. Reduced Thrust force contributes to lesser delamination in particle board. Hence minimisation of both surface roughness and delamination is desired and hence optimisation of both responses is done simultaneously using grey relational analysis.

“Stolt Rotterdam” – The sinking of an acid freighter

The Stolt Rotterdam tanker ship, filled with nitric acid, was unloading at the Krefeld-Uerdingen terminal on the Rhine River in November 2001. Nitric acid ran out of the stainless steel tanks into the ship’s hull and damaged the structural steel. The ship then caught fire and sank at the terminal. Large quantities of nitrogen oxides were emitted, which drifted towards a residential area. Additionally, a mixture of acid and water was introduced into the Rhine River. The area became hazardous to people and the natural environment; however, the imminent danger for the residents and the environment was reduced because of the protective measures against pollution and the good teamwork between local authorities, fire brigades and the Bayer AG company. The acid was drained off of the ship using a controlled discharge of the acid into the river. Through the use of this measure, the ship was salvaged, limiting the pollution to the area and removing the health hazards to the people and the environment. After the ship was salvaged, the river police, along with assistance from the BAM Federal Institute for Materials Research and Testing, impounded the ship and selected corroded parts for further examination. Some of these components have been examined in detail by the BAM. These material investigations contributed to the elucidation of the origin of the leak in the floor panel. The cause of damage was deemed to be a result of a construction flaw at the enamelled valve on the load and discharge pipes.The results from the comparative corrosion testing using the original structural steel and 60% acid revealed that the valves began to leak at least 8h prior to the incident at the terminal.

Characterising the unique polychrome sinopia under the Lod Mosaic, Israel: pigments and painting technique

A sinopia, usually a monochrome preparatory drawing made on a mortar substrate, was used in the Graeco-Roman world either as a base for frescoes or to facilitate the application of coloured mosaic tesserae on walls or floors. In 2009, during the detachment of the Lod Mosaic (Israel), an unexpected and, for the Classical Roman era, a unique, polychrome sinopia was revealed under one of the floor panels. The palette of colours includes red and yellow ochre, green earth, carbon black and the valuable red pigment cinnabar, all applied with the fresco technique, as attested by microstratigraphy.

Cyclic behaviour of typical metal connectors for cross-laminated (CLT) structures

An extended experimental programme on typical cross-laminated (CLT) connections was performed at IVALSA Trees and Timber Institute. The paper discusses the results of monotonic and cyclic tests in shear and tension (pull-out) carried out on hold-downs and steel angle brackets used to anchor the wall panels to foundations or to connect wall panels to floor panels. Mechanical properties such as strength, stiffness, energy dissipation, impairment of strength and ductility were evaluated and are critically discussed in the paper. Significant ductility and energy dissipation was attained in most of the tests. Nevertheless, brittle failure modes were observed in some tests, indicating the need for introduction of capacity based design principles for CLT connections. The overstrength factors, which are needed for capacity based design, were also evaluated for the different types of connection tested. A comparison between the test results and the analytical formulas provided by current codes of practice and new proposals is also provided. The approach developed by Uibel and Blas gives slightly more accurate CLT metal strength predictions compared to the existing formulas in Eurocode 5. Both approaches lead to very conservative results. However, analytical models for the prediction of CLT metal connectors’ stiffness significantly overestimate the experimental values. Therefore, it is recommended that currently only experimental strength and stiffness values of hold-downs and angle brackets be used in seismic analyses. Some proposals to improve the mechanical performance of metal connectors in terms of strength and stiffness are also given based on this experimental and analytical study.

Prediction of bending stiffness and moment carrying capacity of sugi cross-laminated timber

Cross-laminated timber (CLT) panels consist of several layers of lumber stacked crosswise and glued together on their faces. Prototype sugi CLT floor panels were manufactured and bending tests were carried out under the different parameters of lumber modulus of elasticity (MOE), number of layers, thickness of lumber and thickness of CLT panels. On the basis of above tests, bending stiffness and moment carrying capacity were predicted by Monte Carlo method. MOE of lumber was measured by using grading machine and tensile strength of lumber was assumed to be 60 % of bending strength based on the obtained bending test. Bending stiffness EI of CLT panels could be estimated by adopting composite theory and equivalent section area. Experimental moment carrying capacity showed 12 % higher value than the calculated moment carrying capacity by average lumber failure method, and also showed 45 % higher value than the calculated moment carrying capacity by minimum lumber failure method due to the reinforcement of the outer layer by the neighboring cross layer.

Precast/Prestressed Concrete Sandwich Panels for Thermally Efficient Floor/Roof Applications

AbstractPrecast concrete floor systems represent a major component of the cost and weight of precast concrete buildings. Hollow-core (HC) planking is considered the most common precast concrete floor system for residential and commercial buildings because of their economy, light weight, structural capacity, and ease of production and erection. However, the high thermal conductivity of HC planks hinders their use in radiant heated floor and roof applications where thermal insulation is needed. This paper presents the development of a precast/prestressed concrete sandwich floor panel that consists of an internal wythe of insulation and two external wythes of concrete similar to those used in sandwich wall panels. The main difference between the sandwich floor and wall panels is the design of shear connectors between concrete wythes to achieve full composite action under ultimate loads while simultaneously having an adequate creep resistance under sustained loads and acceptable deflection under live loads. T...