Perforated Foam Research Articles

Development of Forecasting Model for Prediction of Compressive Strength of Foamed Concrete using Density with W/C ratio and S/C ratio by the Application of ANN

This Artificial neural network study presents the prediction model for a cellular foamed concrete. Foamed Concrete is a cementitious material that should consist of a minimum of 20% of foam, which is mechanically entrained using the mechanical generator of foam. Foamed Concrete possesses a cellular microstructure. By which they become a highly air-entrained system having unusual physical and mechanical properties. It is the perfect mixture of cement, water, sand (fine aggregate), and perforated foam. Published information related to the prediction of foamed concrete is limited, and rational guidelines to evaluate the compressive strength of the concrete are not widely available. This study aims to encourage the strength of foamed concrete economically and predict the strength in the compressive form of concrete. A dataset of 153 instances having an input parameter proportion of Density, W/C ratio, & S/C ratio have been taken to predict compressive strength to elevate and expand the precision and accuracy of the foamed concrete. The data has been trained with the help of ANN, in which we conduct a network analysis to forecast the compound’s performance and stability. The deficiency of strength of foamed concrete is to be sorted out with the help of ANN, and the prominent and reliable equation for the compression power is generated. ANN helps to optimize the compressive strength at the time of physical casting of the concrete.

On the use of a trilinear traction-separation law to represent stitch failure in stitched sandwich composites

Modern aircraft employ the use of lightweight engineering materials such as sandwich composites to increase the flexural rigidity of their structural components. These sandwich composites are limited by their low interfacial strength between the outer facesheets and internal core, which can result in facesheet-core debonding at relatively low out-of-plane loads. In this study, sandwich composites that are reinforced with through-the-thickness stitching are considered. Stitched sandwich composite specimens, fabricated from 110 kg/m3 perforated foam core with cross-ply carbon/epoxy facesheets, were manufactured with different combinations of stitch densities (0.0016–0.01 stitches/mm2) and linear thread densities (400–1200 Denier) of through-the-thickness reinforcement. Single cantilevered beam (SCB) tests were performed to characterize the facesheet-core debonding within the stitched sandwich composites. Unique fracture morphologies were observed that exhibit dependency on stitch processing parameters. A discrete cohesive zone modeling approach is used to simulate the separation of the facesheet from the core. Three-dimensional finite element analysis reveals crack curvature near the stitching. Good agreement between predicted and experimental measurements were obtained.

Sound Absorption Properties of Perforated Recycled Polyurethane Foams Reinforced with Woven Fabric.

The acoustic properties of recycled polyurethane foams are well known. Such foams are used as a part of acoustic solutions in different fields such as building or transport. This paper aims to seek improvements in the sound absorption of these recycled foams when they are combined with fabrics. For this aim, foams have been drilled with cylindrical perforations, and also combined with different fabrics. The effect on the sound absorption is evaluated based on the following key parameters: perforation rate (5% and 20%), aperture size (4 mm and 6 mm), and a complete perforation depth. Experimental measurements were performed by using an impedance tube for the characterization of its acoustic behavior. Sound absorption of perforated samples is also studied—numerically by finite element simulations, where the viscothermal losses were considered; and analytically by using models for the perforated foam and the fabric. Two textile fabrics were used in combination with perforated polyurethane samples. Results evidence a modification of the sound absorption at mid frequencies employing fabrics that have a membrane-type acoustic response.

Strength Characteristics of Preformed Foam Concrete

The study deals with the usage of perforated foam of various percentages to that of coarse aggregate to produce light weight concrete. With the day to day increase in industries and civilization’s expansion it has become very much necessary to produce structures with proficiently lesser weight. Its usage has become more proficient in construction of building in earthquake prone areas. This experimental investigation deals with the study of strength parameters of light weight concrete by performing various strength test and its various behavior s such as compression, tensile and flexure are studied by adding preformed foam at various proportions of 0%, 2%, 5%, 10%, 20% and 40%. All these strength parameter test are performed on 7th day, 14th day and 28th day respectively from day of casting.

Mechanical performance of marine sandwich composites subjected to flatwise compression and flexural loading: Effect of resin pins

Mechanical performance of marine sandwich panels comprising E-glass/vinyl ester face sheets and perforated poly-vinyl chloride foam core was evaluated and compared with conventional foam core sandwich panels. Circular holes through the foam core thickness were drilled with 12 different arrangements in square patterns and the holes were filled with the resin during the infusion process which created the through-the-thickness solid resin pins. The effect of each pattern on the flatwise compression and core shear properties of the sandwich panels were experimentally investigated. The three-point bending maximum failure load of perforated foam core sandwich panels was increased over 133.8% by increasing the diameter of the resin pins at the expense of increased panel weight up to 67%. The flatwise compression stress to induce core crushing was significantly increased by reinforcing the resin pins.

Air Permeability of Thick Foams: Flow Numerical Simulations

From measured data are determined permeability parameters of thick perforated foam samples, used as car seats cushions. Parameters are used for numerical flow simulations in foam samples. Model of detailed geometry gives good view about detailed flow field (pressure and velocity) in foam volume, influenced by perforations and grooves. However, simulated flow is several times different from measured one. The main flow is through perforations (99%) and flow through foam is of two orders lower. Using homogenous geometry with “averaged” permeability parameters, evaluated from measured values, the coincidence of measured and simulated flow is very good, difference of 1-5%. However, it is not possible to get any details of flow in foam volume. Using inlet layer, the flow is decreasing, first in perforations and the ratio between perforation and foam flows is more balanced.

Silencer design for awning windows: Modified Helmholtz resonators with perforated foam

In order to dissipate sound which passes through an open awning window, we have developed a hybrid absorber made of a modified Helmholtz resonator with perforated foam. Generally, acoustic absorbers are divided into two major categories. The first one is porous materials which dissipate the acoustic wave in a visco-inertial form and heat. The second category is systems which absorb the energy of the acoustic wave by resonance. The aim of this work was to design a hybrid absorber which incorporates the benefits of the two categories for both high frequencies (conventional foam) and low frequencies (resonator). After describing the concept and the principles, we present the prototype which was built and tested under laboratory conditions between two reverberant rooms to attenuate the sound when an awning window is open. The prototype allows reduction of noise transmission (up to 6 dB) at low and high frequencies.

Mechanical properties of sandwich panels with perforated foam cores

Mechanical properties of sandwich panels employing E-glass/polyester face sheets bonded to a perforated foam core are evaluated and compared to sandwich panels fabricated with conventional plain sheet cores. Through-thickness compression testing, plate shear, face—core fracture toughness and weight measurements after infusion are used to evaluate the performance of both core configurations in sandwich panels. The influence of full and partial filling of the perforations with resin is also discussed based on experimental results and finite element analysis. It is found that complete filling of the core perforations with resin provide increased compression properties to the sandwich, at the expense of about 30% weight gain in the panel. Crack may be temporarily arrested when it meets a resin filled perforation, but this localized arrest is minor and does not significantly increase the global fracture toughness of the face—core interface. Partial resin filling of the perforations causes stress concentrations which significantly decrease the mechanical properties of the sandwich structure.

English

The paper deals with the fabrication and flexural properties studies of stitched core foam sandwich structures by varying thread TPI(Twist Per Inch).10 mil silane treated open form E – glass fabric was used as a face sheet. Divinycell foam H80 was used as a core material. The perforated foam was placed in between the face sheets and hand stitch method was used for stitching the face sheet and the foam by glass yarn (37 1/5) of 3, 3.8, 5.3. The panels were fabricated under Vacuum bag moulding process The flexural strength and flexural deflection of fabricated specimens were determined through three point bending test (ASTM C 393-62). A significant increase in flexural rigidity of foam was observed in the panel stitched with thread of 3 TPI when compared with other layers.

Moisture Transfer Through Impermeable Foam Insulations

The biophysical characteristics of perforated foam systems are presented in terms of experimentally determined values of insulation and moisture vapor permeance (MVP). The effect of windbreak motion on the moisture vapor transfer through such systems is discussed. A theoretical comparison among systems is given in terms of environmental range using the concept of moisture permeability index.

Extension traction with perforated foam rubber strips.

The application of perforated foam rubber strips with rayon or drill cloth backing to an extremity is a type of extension traction that I have found to be simple and easy to apply. Foam rubber consists of an infinite number of air bubbles in a matrix of rubber. As this mass is sliced longitudinally, there is created a gripping surface consisting of many concavities with rubber septums. Perforations made in the rubber permit an even better grip on the surface and allow air to reach the skin. The septums act as treads against the skin and hair. Hair acts advantageously when foam rubber is used, in contrast to the discomfort it causes when adhesive plaster is used. The foam rubber is held snugly and smoothly against the skin by an elastic bandage. No shaving or other preparation of the skin is required. This method is particularly useful in applying traction