Fiber Panel Research Articles

Star centroiding error compensation for intensified star sensors.

A star sensor provides high-precision attitude information by capturing a stellar image; however, the traditional star sensor has poor dynamic performance, which is attributed to its low sensitivity. Regarding the intensified star sensor, the image intensifier is utilized to improve the sensitivity, thereby further improving the dynamic performance of the star sensor. However, the introduction of image intensifier results in star centroiding accuracy decrease, further influencing the attitude measurement precision of the star sensor. A star centroiding error compensation method for intensified star sensors is proposed in this paper to reduce the influences. First, the imaging model of the intensified detector, which includes the deformation parameter of the optical fiber panel, is established based on the orthographic projection through the analysis of errors introduced by the image intensifier. Thereafter, the position errors at the target points based on the model are obtained by using the Levenberg-Marquardt (LM) optimization method. Last, the nearest trigonometric interpolation method is presented to compensate for the arbitrary centroiding error of the image plane. Laboratory calibration result and night sky experiment result show that the compensation method effectively eliminates the error introduced by the image intensifier, thus remarkably improving the precision of the intensified star sensors.

Sustainable Building Material for Noisy Urban Residential Space

Researches on noise control have been conducting until now. Eventhough correlation model of housing orientation to airport's runway was found out, it would be better if housings are equipped by materials which can absorb noise. This paper will refresh the housing master plan design near airport continued with the possibility of housing on controlling noise disturbance. Method used is descriptive analysis on reviewing sustainable materials for low cost housings. Results of researches show that wood sawdust and coconut fibre panel have quite good acoustical performances and could be used to be wall layering in noisy urban housings.

Distributed internal strain measurement during composite manufacturing using optical fibre sensors

After manufacturing a composite laminate, it is expected to store residual stresses that might affect the mechanical response of the plate. An optical fibre sensor was embedded in an epoxy carbon fibre panel, measuring the development of residual strain by monitoring in-situ and in real-time the manufacturing process, from the resin infusion to the curing cycle, and the changes experienced within. An optical sensor interrogator detects and measures changes in strain and temperature along the optical fibre length with high precision and accuracy, making it possible to obtain a full strain/temperature profile. Data acquired from the embedded sensor led to track and characterize the strain profile at every stage of the manufacturing process. This work showed that the infusion stage is highly related to the residual strain after the curing process. Moreover, the residual strain is 40% higher near the edge compared to the mean value measured in the laminate.

Mode III Loading of Composite Panels

Efficient design of modern aircraft requires an understanding of the mechanical behavior of carbon fiber panels under both in-plane and out-of-plane loading conditions. Currently, relatively little published literature exists for out-of-plane shear (mode III) loading. This paper presents both experimental and computational results for strain fields showing damage initiation, and propagation of notched carbon fiber panels under mode III loading. Experimentally, strain fields were measured using digital image correlation. Computationally, the commercial finite element package Abaqus, using typical composite analysis techniques, was used to calculate strain fields. Comparisons were made between measured and calculated values. Experimental results indicated that areas of both tensile and compressive strain concentrations existed at the notch tip. Damage initiation occurred in these areas, typically only in one or the other. Subsequent damage propagation occurred both in areas of elevated tensile strain and in areas of elevated compressive strain. Computational results showed differences of typically to as compared with experimental results for notch tip strain concentrations before damage and with larger differences after damage had occurred. Overall, these results provide information on how notched carbon fiber panels behave under mode III loading and the effectiveness of a commonly used computational approach in predicating this behavior.

Preliminary evaluation of the sound absorption coefficient of a thin coconut coir fiber panel for automotive applications

Absorbent materials are fibrous or porous and must have the property of being good acoustic dissipaters. The noise reduction process occurs due to transformation of a part of the sound energy into heat. This process occurs when a sound wave propagates through pores or irregular arrangement of fibers. Sound propagation causes multiple reflections and friction of the air present in the absorbent medium transforming sound energy into heat. The acoustic surface treatment with absorbent material are widely used to reduce the reverberation in enclosed spaces or to increase the sound transmission loss of acoustic panels. In addition, these materials can also be applied to acoustic filters with the purpose to increase their efficiencies. The sound absorption depends on the excitation frequency of the sound and it is more effective at high frequencies. Natural fibers such as coconut coir fiber have a high potential to be used as sound absorbing material. Natural fibers are agriculture waste, manufacturing this fiber is a natural product, therefore an economic and interesting option. This work compares the sound absorption coefficient of a thin coconut coir fiber panel in relation to a composite panel made of fiberglass and expanded polyurethane foam used in the automotive industry. The evaluation of sound absorption coefficient was carried out with the impedance tube technique.

Study on Dynamic Responses and Reinforcement of Reinforced Concrete Columns Subjected to Blast Loading

The terrorism and regional conflicts posed a threat to the world peace. Some terrorist explosions caused collapse of the buildings, which brought heavy tragedies to the human components. Therefore research on damage of structural components and resistance to damage have become the focus of our attention. Finite element software LS-DYNA was applied to simulating the response of reinforced concrete columns under blast loading. And analysis on dynamic response under different loading period was carried out. By studying on the stress and strain of reinforced concrete columns subjected to blast loading, the possible failure modes were obtained. In addition, the bearing capacities of concrete columns that are reinforced with carbon fiber and steel panel were analyzed, and the reinforcement effects were compared to provide reasonable reinforcement schemes for structures blast-resistant design.

Green Materials Comparison of Sawdust and Coconut Fiber Acoustical Waffle Panel

The natural wealth of Indonesia produces a wide range of natural resources. This research will discuss sawdust and coconut fiber for example from natural resources which can be processed into building materials. Various researches have studied the absorber made from sawdust and coconut fiber, but only a few studies that made the absorber material that had the texture of waffle on its surface. The research method used was the method comparisons of density, absorption coefficient and Sound Transmission Loss (STL). The result is that the waffle panel from sawdust has a higher density than the waffle panel made of coconut fiber. The STL of the coconut fiber panel has ranged between 46,134 – 51,312 dB. This value is lower than the STL material of sawdust that has a value between 47,301 – 62,688 STL. The absorption coefficient of coconut fiber panels is 0,432–0,511, while the absorption coefficient of sawdust panel has range of 0,469 – 0,529.

Localisation and identification of fatigue matrix cracking and delamination in a carbon fibre panel by acoustic emission

BackgroundThe use of Acoustic Emission (AE) as a Structural Health Monitoring (SHM) technique is very attractive thanks to its ability to detect not only damage sources in real-time but also to locate them. MethodsTo demonstrate the AE capabilities on known damage modes, a carbon fibre panel was manufactured with cut fibres in a central location and subjected to fatigue loading to promote matrix cracking. Subsequently, a delamination was created within the panel using an impact load, and the test was continued. ResultsAE signals were located within the crack area in the first part of the test. After impact, AE signals were detected from both areas under fatigue loading; signals from this area were located and used for further analysis with the neural network technique. ConclusionsThe application of an unsupervised neural network based classification technique successfully separated two damage mechanisms, related to matrix cracking and delamination. The results obtained allowed a more detailed understanding of such sources of AE in carbon fibre laminates.

ATR FTIR Mapping of Leather Fiber Panels

Leather fiber panels are very promising materials for many applications, not only for the easy availability of the constituents but also for their outstanding fi re-retardant properties. These innovative composite panels can be an excellent material for building insulation, and in recent times, the interest of industries in this composite board has considerably arisen. For this reason the discrimination of the components in the leather fiber panels is becoming fundamental in order to ensure their homogeneous properties. A method to characterize the surface of these materials is then required. An ATR FTIR mapping system for the leather fiber panels has been performed with a Perkin–Elmer microscope coupled with a Frontier FTIR spectrometer. The system has successfully allowed transforming the optical image to a chemical one. This technique can be considered as a right tool for routine controls of the surface quality, especially when the leather shavings cannot be optically distinguished.

Classification of acoustic emission data from buckling test of carbon fibre panel using unsupervised clustering techniques

Acoustic emission is widely used for mechanical diagnostics and to characterise damage in composite materials. Distinction between different damage mechanisms is still one of the major challenges and remains an unresolved issue. The objective of cluster analysis is to separate an acoustic emission data set into multiple classes that reflect different acoustic emission sources. This article is concerned with the implementation of unsupervised clustering techniques to classify acoustic emission transients from a carbon fibre laminate buckling test. A new approach to signal feature extraction was utilised, whereby principal components provide signal features that represent the greatest data variance while remaining linearly uncorrelated with each other; feature selection was undertaken using a hierarchical clustering method and finally a cluster analysis was performed using k-means and Fuzzy C-means techniques. The aim of the work is to reduce the data required in the classification process, thereby reducing the processing time and computational power required, without significantly affecting the classification result. Thus, an approach which is more suited to online processing, allowing fast and efficient processing and storage of data is provided. The proposed unsupervised clustering analysis was able to separate acoustic emission signals into two different clusters that were correlated to the damage mechanisms observed. The results show that the clustering groups have a good fit with ultrasonic C-scan and digital image correlation strain data. The application of a clustering process that uses the most effective acoustic emission features as input data is an objective method, and this investigation shows that it may be a useful complement in the field of non-destructive evaluation.

Absorption Coefficient of Acoustic Coir Fibre Panel and Effects of Varying Percentage of Perforated Plates

The effects of perforated plates with different percentage of perforation affecting the sound absorption coefficient of coir fibre acoustic panels were investigated. Two types of perforated plates of 6.93 and 19.24% perforation were combined with the similar coir fibre layer. Acoustic tests for measuring the sound absorption were conducted in the reverberation room according to the ISO 354:2003 standard. The based coir fibre panel showed to possess good sound absorption characteristics from intermediate to high frequency range (800-2000 Hz). Perforated plates (6.93 and 19.24%) with coir fibre panel were found to achieve maximum sound absorption coefficients of 0.77 and 0.63 at 2000 Hz, respectively. As frequency increased to 4000 Hz, the sound absorption coefficient for the higher percentage perforation produced a higher sound absorption coefficient value.

Effect of Density on the Sound Absorption of Date Palm Fibers

An experimental study on the effect of panel density on the sound absorption properties of a date palm fiber panel has been presented in this paper. The experiments were carried out by using impedance tube at the Acoustic Lab, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia. The date palm fiber was tested for densities of 77 kg/m3, 100 kg/m3 and 125 kg/m3.The results show that the values of absorption coefficient improve when increasing the density of the panel. Noise reduction coefficient (NRC) was computed to compare the performance of the palm date fiber samples for the different densities. The NRC increases by increasing the density.

A Preliminary Study on the Sound Absorption of Date Palm Fibers

In this study sound absorption properties of a single layer date palm fiber has been investigated. Experimental measurements were carried out using impedance tube at the acoustic lab, Faculty of Engineering, Universiti Kebangsaan Malaysia. A constant thickness sample was considered in this study.The results show that the values of absorption coefficient are small at low frequencies, rising with increasing frequency but exhibiting a significant peak. The low density of the sample is reflected in the overall sound absorption performance of the date palm fiber. An improvement in the sound absorption in the lower frequency range was achieved by backing the sample with air gap of different thicknesses of 10 mm, 20 mm and 30 mm. The increase in the air gap thickness moved the peaks toward lower frequencies and improved the low frequencies absorption. However, that increase coincided with reduction of absorption in medium frequency range and reduction in the absorption peak. A linear relationship was found between sound absorption peaks and the air gap thickness. The performance of the date palm fiber can be improved by increasing the density of the sample, using different sample thicknesses and adding perforated plates to the date palm fiber panel.

Damage classification in carbon fibre composites using acoustic emission: A comparison of three techniques

Classifying the type of damage occurring within a structure using a structural health monitoring system can allow the end user to assess what kind of repairs, if any, that a component requires. This paper investigates the use of acoustic emission (AE) to locate and classify the type of damage occurring in a composite, carbon fibre panel during buckling. The damage was first located using a bespoke location algorithm developed at Cardiff University, called delta-T mapping. Signals identified as coming from the regions of damage were then analysed using three AE classification techniques; Artificial Neural Network (ANN) analysis, Unsupervised Waveform Clustering (UWC) and corrected Measured Amplitude Ratio (MAR). A comparison of results yielded by these techniques shows a strong agreement regarding the nature of the damage present in the panel, with the signals assigned to two different damage mechanisms, believed to be delamination and matrix cracking. Ultrasonic C-scan images and a digital image correlation (DIC) analysis of the buckled panel were used as validation. MAR’s ability to reveal the orientation of recorded signals greatly assisted the identification of the delamination region, however, ANN and UWC have the ability to group signals into several different classes, which would prove useful in instances where several damage mechanisms were generated. Combining each technique’s individual merits in a multi-technique analysis dramatically improved the reliability of the AE investigation and it is thought that this cross-correlation between techniques will also be the key to developing a reliable SHM system.

Implications of fiber characteristics and mat densification on permeability, compaction and properties of kenaf fiber panels

In the manufacturing of medium density and high density fiberboards the fiber characteristics and mat density substantially influence mat permeability, compaction pressure and panel's physicomechanical properties. In this paper, the permeability and compaction response of kenaf bast fiber mats are experimentally determined at three fiber lengths for both dry and resinated fiber mats with various levels of mat densification. The mats of long fibers have demonstrated higher permeability and require higher compaction pressure than short fiber mats at the same level of densification. Furthermore, kenaf panels in the density range of 800kg/m3 to 1100kg/m3 are manufactured with commercial melamine urea formaldehyde resin and three fiber categories. The panels are evaluated to demonstrate the effects of these factors on a panel's physicomechanical properties. The higher compaction pressure and good stress distribution with long fibers have resulted in higher mechanical properties than those of short fiber panels. On the other hand, a decrease in fiber length has lowered the mat permeability, resulting in significant improvements in dimensional properties. The panel physicomechanical properties can also significantly improve by increasing the panel density. The high density kenaf panels have shown excellent mechanical properties which are well above the standard requirements of MDF and HDF panels according to (ANSI, A208.2: 2009) and (ANSI, A135.4-2012) standards.

Recycled-PET fibre based panels for building thermal insulation: Environmental impact and improvement potential assessment for a greener production

A screening of Life Cycle Assessment for the evaluation of the damage arising from the production of 1 kg of recycled Polyethylene Terephthalate (RPET) fibre-based panel for building heat insulation was carried out according to the ISO 14040:2006 and 14044:2006. All data used were collected on site based on observations during site visits, review of documents and interviews with technical personnel and management. These data were processed by using SimaPro 7.3.3, accessing the Ecoinvent v.2.2 database and using the Impact 2002+ method. The study showed damage to be equal to 0.000299 points mostly due to the: 1) PET thermo-bonding fibre supply from China by means of a freight-equipped intercontinental aircraft; 2) production of bottle-grade granulate PET; 3) medium voltage electricity consumption during the manufacturing of RPET fibre panel. It was also highlighted that there were environmental benefits due to recycling through mainly avoiding significant emissions and reduced resource consumption. An improvement assessment was carried out to find solutions aimed at reducing the damage coming from the most impacting phases. Furthermore, the environmental impacts due to the production of the analysed RPET fibre-based panel were compared to other materials with the same insulating function, such as polystyrene foam, rock wool and cork slab. Finally, the environmental benefits of the recycling of PET bottles for flake production were highlighted compared to other treatment scenarios such as landfill and municipal incineration.

Influence of coupling agent content on the properties of high density polyethylene composites reinforced with oil palm fibers

Oil palm fiber reinforced high density polyethylene (HDPE) composites which can be used in several applications (mechanical part, fiber panel, etc.) were manufactured by twin-screw extrusion followed by compression molding. In particular, the effect of coupling agent (maleated polypropylene, MAPP) concentration (0, 2, 4 and 6wt.%) was investigated for 30 and 40wt.% oil palm fiber. Scanning electron microscopy (SEM), Fourier transforms infrared spectroscopy (FT-IR), dynamic mechanical thermal analysis (DMTA) and mechanical testing (tension and impact) were carried out to determine the effect of fiber and compatibilizer contents. The results showed that compatibilized composites have increased stiffness due to enhanced interfacial adhesion between the fibers and the matrix, as well as better homogeneity (better fiber dispersion) due to chemical bonding. The optimum MAPP content was found to be 4% for the range of conditions tested.

Compression Buckling Response of Tow-placed, Variable Stiffness Composite Panels with Sine Curved and Tangent Curved Fibers

Tailoring of composite laminated panels by Variable Angle Tow (VAT) steering fibers in their optimal spatial orientations provides a unique opportunity to maximize performance. Increased buckling response of the laminates by VAT steering technique may directly provide significant weight savings by redistributing loads in a benign manner. The aim of this work is to design tow-placed, variable stiffness composite panels with resistance to buckling by steering sine curved and tangent curved fibers. Buckling behaviors of two types of VAT panels and three typical types of straight fiber panels ([45/-45/0/90]s,[±45]2s, [0/90]2s) are investigated by finite element numerical simulations. It is found that the VAT panels with sine curved and tangent curved fibers show much better buckling performance to traditional straight fiber panels, with 9.25%-30.75% and 8.18%-29.47% improvement in buckling load respectively and a more uniform stress distribution. These results demonstrate that the design of composite laminated panels with sine curved and tangent curved fiber formats has the potential for buckling performance improvements in structural efficiency, and sine curved fibers may enhance buckling property of composite laminates better than tangent curved fibers do.

Experimental investigation of sound absorption properties of perforated date palm fibers panel

This paper presents the sound absorption properties of a natural waste of date palm fiber perforated panel. A single layer of the date palm fibers was tested in this study for its sound absorption properties. The experimental measurements were carried out using impedance tube at the acoustic lab, Faculty of Engineering, Universiti Kebangsaan Malaysia. The experiment was conducted for the panel without air gap, with air gap and with perforated plate facing. Three air gap thicknesses of 10 mm, 20 mm and 30 mm were used between the date palm fiber sample and the rigid backing of the impedance tube. The results showed that when facing the palm date fiber sample with perforated plate the sound absorption coefficient improved at the higher and lower frequency ranges. This increase in sound absorption coincided with reduction in medium frequency absorption. However, this could be improved by using different densities or perforated plate with the date palm fiber panel.

Optimizing the process of forming organic-synthetic fiber panels with the use of expert estimates

This article is devoted to optimizing the process of producing organic-synthetic fiber panels. Derringer’s special desirability functions and Saati’s method are used to solve a problem involving multi-criterional optimization: determine the dependences of the physico-mechanical indices of the panels on their percentage content of textile wastes and the pressing temperature.