There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

This chapter introduces the finite element method (FEM) as a tool for solution of classical electromagnetic problems. Although we discuss the main points in the application of the finite element method to electromagnetic design, including formulation and implementation, those who seek deeper understanding of the finite element method should consult some of the works listed in the bibliography section.

Introduction to the Finite Element Method

This chapter introduces the subject of statistical pattern recognition (SPR). It starts by considering how features are defined and emphasizes that the nearest neighbor algorithm achieves error rates comparable with those of an ideal Bayes’ classifier. The concepts of an optimal number of features, representativeness of the training data, and the need to avoid overfitting to the training data are stressed. The chapter shows that methods such as the support vector machine and artificial neural networks are subject to these same training limitations, although each has its advantages. For neural networks, the multilayer perceptron architecture and back-propagation algorithm are described. The chapter distinguishes between supervised and unsupervised learning, demonstrating the advantages of the latter and showing how methods such as clustering and principal components analysis fit into the SPR framework. The chapter also defines the receiver operating characteristic, which allows an optimum balance between false positives and false negatives to be achieved.

Statistical Pattern Recognition

This study provides a bibliographic review in the broad field of green composites seeking-out for materials with a potential to be applied in the near future on automotive body panels. Hereupon, materials deriving from renewable resources will be preferred as opposed to the exhaustible fossil products. With the technical information of bio-polymers and natural reinforcements a database was created with the mechanical performance of several possible components for the prospect green composite. Following the review, an assessment is performed where aspects of suitability for the candidate elements in terms of mechanical properties are analyzed. In that section, renewable materials for matrix and reinforcement are screened accordingly in order to identify which hold both adequate strength and stiffness performance along with affordable cost so as to be a promising proposal for a green composite.

Green composites: A review of adequate materials for automotive applications

http://jultika.oulu.fi/files/nbnfi-fe2017112150815.pdf

One-part alkali-activated materials : a review

Preparation of honeycomb layer is a critical step for successful fabrications of thermoformed based sandwiched structures. This paper deals with an initial investigation on the rapid manufacturing process of corrugated sheet with 120° dihedral angles. Time history of local displacements and thickness, assuming viscous dominated material model for a 1mm thick thermoformable material, was computed by using ANSYS® Polyflow solver. The quality of formed surfaces was evaluated for selection of mould geometry and assessment of two common variants of thermoforming process. Inadequate mesh refinement of a membrane elements produces satisfactorily detailing and incomplete forming. A perfectly uniform material distribution was predicted using drape forming process. However, the geometrical properties of vacuum formed part are poorly distributed and difficult to control with increasing inflation volumes. Details of the discrepancies and the contributions of the CAE tool to complement traditional trial and error methodology in the process and design development are discussed.

https://iopscience.iop.org/article/10.1088/1757-899X/114/1/012012/pdf

CAE applications in a thermoforming mould design

The use of electric vehicle especially electric bus in on the rise. Unfortunately, it still has a downside which is not having enough distance compared to the conventional bus which uses diesel as its energy source. One of the reasons that affect the distance the electric bus can travel is the weight of the bus. The lighter the bus, the longer it can travel. Because of that, a new way of building the chassis and bus body structure that uses the composite material to replace not just heavy but also rusty prone metallic material has been developed. Now that the weight has improved, it creates another problem where the current method of inspecting the quality of the product during manufacturing is not just error-prone, but also take a longer time than it is allocated. The available tool in the market is expensive and a lot of investment is needed to make it work with a large structure such as the bus that a small company could not afford. Due to that, this project is going to address the need by designing and developing a thermal imaging tool for composite damage detection. The design process is done by using a model-based systems engineering method to identify the needs of the user and develop the functional requirement it needs based on that. Then, the structure of the tool is allocated to the functional requirement and eventually, the hardware needed for it to become a complete product is identified. Once the hardware has been identified, it now can be integrated and several conceptual housing designs are developed where the final selection of the design is selected by using the Pugh evaluation matrix method. The integrated hardware is then put to test to ensure the tool works as intended. Based on the experiment conducted, the tool can detect a sub-surface damaged-induced specimen up to 2 mm depth. More than that, a longer time is needed which is not productive. In conclusion, although the developed tool meets all its objectives, there is still room for improvement to make it work efficiently in the field.

Preliminary Design of a Low-Resolution Thermography Camera System for Subsurface Defect Detection of a Thin Composite Plate; A Case Study for Composite Electric Bus Structure

A numerical investigation to optimize the carbon/epoxy multi layer composite rotor is performed for the spacecraft energy storage application. A high-speed double and triple layer rotor design is proposed and different composite materials are tested to achieve the most suitable recipe. First, analytical rotor evaluation was performed in order to establish a reliable numerical composite rotor model. Subsequently, finite element analysis is employed in order to optimize the double and triple layer composite rotors. Then, the modal analysis was carried out to determine the rotor natural frequencies. The rotor stress distributions and the rotor mode shapes show that a safe operational regime below 46, 000 rotations per minute is achievable.

/pdf/critical-speeds-for-carbon-epoxy-composite-rotors-in-4vyisgmfnb.pdf

Critical Speeds for Carbon/Epoxy Composite Rotors in Spacecraft Energy Storage Applications

Effect of different amount chitosan, starch and glycerol in composite edible coating

This paper presents an improved version of a wireless device embedded with a smart PZT sensor to detect flaws and structural defects on selected investigated structure. Smart PZT sensors were used as an actuator and sensor, coupled with two XBee's and one signal generator IC chip. Programme execution on transmitting and receiving the ultrasonic guided wave via the PZT sensor had been written in MATLAB. The developed source code is basically to receive serial data from one Xbee to another remote Xbee attached to the investigated structural system. The refined waveform response is utilised for prognosis of the true structural status. The 4-mm simulated holed into one of the aluminium structural plate is benchmarked with its pristine condition in validating the effectiveness of the developed SHM wireless module. Results showed that the wave is more even in non-defected area and disrupted in affected area. Ultrasonic waves increase continuously for non-destructive evaluation and structural health monitoring in various structural applications because the guided wave can propagate long distances and reach difficult-to-access regions; for inspecting porous and some non-porous materials ultrasonic waves attenuate fast and are very useful. Recent advances in ultrasonic wave application model and results are discussed in this paper.

Faizal Mustapha

Papers

CAE applications in a thermoforming mould design

Preliminary Design of a Low-Resolution Thermography Camera System for Subsurface Defect Detection of a Thin Composite Plate; A Case Study for Composite Electric Bus Structure

Critical Speeds for Carbon/Epoxy Composite Rotors in Spacecraft Energy Storage Applications

Effect of different amount chitosan, starch and glycerol in composite edible coating

Wireless structural health monitoring (SHM) system for damage detection using ultrasonic guided waveform response