Mechanical Engineering Commons^™

Damage Identification In 3d Printed Metal Parts Using Deep Learning, Romaine Byfield, Alireza Modir, Ibrahim Tansel, Raniero Plaza

36th Florida Conference on Recent Advances in Robotics

An active Structural Health Monitoring (SHM) method called Surface Response to Excitation (SuRE), is used in this study to detect and quantify the damages created by a milling operation on additively manufactured metal plates. This method entails bonding two piezoelectric disks to the test specimens, one to excite it with surface waves from one end of the plate, and the other to sense the dynamic response to excitation at the other end. A sweep sine wave with a duration of 1 ms, ranging from 50-120 kHz is used as the excitation signal. Five stainless steel plates of identical size (195×54×2.5 …

Investigation Into Strain Sensing With Reduced Graphene Oxide, And Applications In Low-Cost Leak Detection And Health Monitoring Of Water Equipment, Armin Yazdi

Theses and Dissertations

Strain gauges are one of the most important transducers that can be used in many applications such as robotics, structural health monitoring, medicine etc. The expensive mass production, as well as lack of high sensitivity, high strain tolerance or high quality can be some of the challenges with the current strain gauges. The reduced graphene oxide possesses many of the excellent properties of graphene while being easy and inexpensive to be mass-produced. However, its electromechanical behavior under strain (especially large strains) has not been well studied. In this dissertation, strain sensing by reduced graphene oxide with Polydimethylsiloxane substrate is investigated …

Drone-Based Vibration Monitoring And Assessment Of Structures, Sabrina Carroll, Joud Satme, Shadhan Alkharusi, Nikolaos Vitzilaios, Austin Downey, Dimitris Rizos

Faculty Publications

This paper presents a novel method of procuring and processing data for the assessment of civil structures via vibration monitoring. This includes the development of a custom sensor package designed to minimize the size/weight while being fully self-sufficient (i.e., not relying on external power). The developed package is delivered to the structure utilizing a customized Unmanned Aircraft System (UAS), otherwise known as a drone. The sensor package features an electropermanent magnet for securing it to the civil structure while a second magnet is used to secure the package to the drone during flight. The novel B-Spline Impulse Response Function (BIRF) …

Nondestructive Evaluation And Structural Health Monitoring Of Manufacturing Flaws And Operational Damage In Composite Structures, Robin James

Theses and Dissertations

Advanced composite materials have begun to be used extensively in the manufacturing of aerospace structures. Composite aerospace structures can develop complex types of damages during the manufacturing stages and operational lifetime. This creates an indispensable demand for appropriate nondestructive evaluation (NDE) and structural health monitoring (SHM) methods that are tailored to specific types of damage. This dissertation addresses innovative methods for NDE and SHM of manufacturing flaws and operational damage in composite structures.

For the NDE of manufacturing flaws in carbon fiber reinforced polymer (CFRP) composites, an eddy current testing (ECT) NDE method has been developed by conducting multiphysics modeling …

Artificial Intelligence Approaches For Structural Health Monitoring Of Aerospace Structures, Kimberly A. Cardillo

Theses and Dissertations

Structural health monitoring (SHM) and non-destructive evaluation (NDE) have been a significant research topic to help with damage detection in aerospace structures. SHM and NDE techniques are based on extracting damage sensitive features to determine the criticality of damage and lifetime of a structure. Acoustic emission (AE) signal detection is an important technique in SHM and NDE especially for fatigue crack growth. AE signals for thin aerospace structures consist of ultrasonic guided Lamb waves that propagate through the structure. This thesis focuses on AE signal repeatability, load at which AE signals occur, feature extraction, artificial intelligence and electro-mechanical impedance of …

Deep Learning Of Nonlinear Dynamical System, Aditya Wagh

Dissertations, Master's Theses and Master's Reports

A data-driven approach, such as neural networks, is an alternative to traditional parametric-model methods for nonlinear system identification. Recently, long Short- Term Memory (LSTM) neural networks have been studied to model nonlinear dynamical systems. However, many of these contributions are made considering that the input to the system is known or measurable, which often may not be the case. This thesis presents a method based on LSTM for output-only modeling, identification, and prediction of nonlinear systems. A numerical study is performed and discussed on Duffing systems with various cubic nonlinearity.

A State Estimation Framework For Fatigue Monitoring And Prognosis Of Minimally Instrumented Structural And Biomechanical Systems, Benjamin Leblanc

Graduate College Dissertations and Theses

Fatigue damage is the continuous degradation of a material, primarily due to the formation of microcracks and resulting from the repeated application of stress cycles. Traditionally a fatigue analysis was performed during the structural design stage of a machine or structure; however, more recently there has been increased interest in the monitoring and prognosis of fatigue damage in existing and operating structures. In monitoring, the structure already exists and its mechanical properties can be estimated by processing sensor measurements and non-destructive testing. The traditional approach to fatigue monitoring is to carry out a visual inspection, find macroscopic cracks and then …

Structural Health Monitoring Of Composite Parts: A Review, Jacob Pessin

Honors Theses

Structural health monitoring has the potential to allow composite structures to be more reliable and safer, then by using more traditional damage assessment techniques. Structural health monitoring (SHM) utilizes individual sensor units that are placed throughout the load bearing sections of a structure and gather data that is used for stress analysis and damage detection. Statistical time based algorithms are used to analyze collected data and determine both damage size and probable location from within the structure. While traditional calculations and life span analysis can be done for structures made of isotropic materials such as steel or other metals, composites …

Structural Health Monitoring Of Laminate Structures Using Shear-Mode Piezoelectric Sensors, Hussain Altammar

Theses and Dissertations

Structural health monitoring (SHM) employing embedded piezoelectric transducers has shown potential as a promising solution for inspection of different engineering structures such as aircraft, bridges, and renewable energy structures. Despite advancements in the field of ultrasonic SHM, inspection of laminate structures is still a major challenge due to their susceptibility to various joint defects. This thesis presents a novel approach to tackle the challenge of inspecting laminate structures using shear-mode (d35) piezoelectric transducers that are made of lead zirconate titanate (PZT).

This study begins with the characterization of d35 piezoelectric transducers using analytical, numerical, and experimental approaches. The results were …

Structural Health Monitoring And Non-Destructive Inspection Of Composite And Metallic Structures, Asaad Qasim Migot

Theses and Dissertations

Structural Health Monitoring (SHM) and Nondestructive Testing (NDT) techniques are being used as effective tools for investigating variety of civil, mechanical, and aerospace applications. In recent years, these techniques become such incredible tools for continuously monitoring of various structures. The aim of the dissertation work is to develop SHM and NDT methodologies for acoustic emission sources localization, damage detection and quantification in metallic and composite structures using a network of sensors, guided wave and developed imaging methods. This work is implemented through preparing metallic and composite specimens, setting up experiments, designing efficient networks of sensors, modeling guided wave interaction with …

Novel Structural Health Monitoring And Damage Detection Approaches For Composite And Metallic Structures, Shervin Tashakori

FIU Electronic Theses and Dissertations

Mechanical durability of the structures should be continuously monitored during their operation. Structural health monitoring (SHM) techniques are typically used for gathering the information which can be used for evaluating the current condition of a structure regarding the existence, location, and severity of the damage. Damage can occur in a structure after long-term operating under service loads or due to incidents. By detection of these defects at the early stages of their growth and nucleation, it would be possible to not only improve the safety of the structure but also reduce the operating costs. The main goal of this dissertation …

Physics-Based Approaches For Structural Health Monitoring And Nondestructive Evaluation With Ultrasonic Guided Waves, Md Yeasin Bhuiyan

Theses and Dissertations

The engineering infrastructures have a growing demand for damage monitoring systems to avoid any potential risk of failure. Proper damage monitoring solutions are of a great interest to this growing demand. The structural health monitoring (SHM) and nondestructive evaluation (NDE) offer appropriate online and offline damage monitoring solutions for a variety of mechanical and civil infrastructures that includes unmanned aerial vehicles (UAV), spaceships, commercial aircraft, ground transportation, wind turbines, nuclear spent fuel storage tanks, bridges, naval ships, and submarines. The fundamentals of the ultrasonic SHM and NDE consist of multi-disciplinary fields. The dissertation addresses SHM and NDE using ultrasonic guided …

Detecting Structural Defects Using Novel Smart Sensory And Sensor-Less Approaches, Amin Baghalian

FIU Electronic Theses and Dissertations

Monitoring the mechanical integrity of critical structures is extremely important, as mechanical defects can potentially have adverse impacts on their safe operability throughout their service life. Structural defects can be detected by using active structural health monitoring (SHM) approaches, in which a given structure is excited with harmonic mechanical waves generated by actuators. The response of the structure is then collected using sensor(s) and is analyzed for possible defects, with various active SHM approaches available for analyzing the response of a structure to single- or multi-frequency harmonic excitations. In order to identify the appropriate excitation frequency, however, the majority of …

Fiber Optic Guided Wave Sensors For Structural Health Monitoring, Erik Frankforter

Theses and Dissertations

Risks and costs associated with aging infrastructure have been mounting, presenting a clear need for innovative damage monitoring solutions. One of the more powerful damage monitoring approaches involves using ultrasonic guided waves which propagate through a structure and carry damage-related information to permanently bonded sensors. Ultrasonic fiber-optic sensors are one of the most promising technologies for this application: they are immune to electromagnetic interference, present no ignition hazard, and transmit their data over tens of kilometers. However, before they can be widely employed, several limitations need to be overcome: poor sensitivity, unidirectional sensing, and loss of ultrasonic functionality due to …

Mens Doped Adhesive And Influence On Fracture Toughness, Kao Z. Yang

FIU Electronic Theses and Dissertations

Composites are in high demand; however, fasteners are often required for joining process and can reduce their advantages. One solution is adhesive bonding, but uncertainty exists regarding long term durability and the ability to interrogate bonds noninvasively. One potential solution to qualify bond integrity over its service life is to dope an adhesive with magneto-electric nanoparticles (MENs). MENs can yield output magnetic signatures that are influenced by bond quality and damage state. In this study, adhesives have been doped with MENs prior to bonding at 1% volume concentration. For optimum implementation, this health monitoring system should be evaluated for effects …

Structural Health Monitoring Of Composite Overwrapped Pressure Vessels, Luca Letizia

Honors Undergraduate Theses

This work is focusing to study the structural behavior of Composite Overwrapped Pressure Vessels (COPVs). These COPVs are found in many engineering applications. In the aerospace field, they are installed onto spaceships and aid the reorientation of the spacecraft in very far and airless, therefore frictionless, orbits to save energy and fuel. The intent of this research is to analyze the difference in performance of both perfectly intact and purposely damaged tanks. Understanding both the source and location of a structural fault will help NASA engineers predict the performance of COPVs subject to similar conditions, which could prevent failures of …

Model Updating And Structural Health Monitoring Of Horizontal Axis Wind Turbines Via Advanced Spinning Finite Elements And Stochastic Subspace Identification Methods, Antonio Velazquez Hernandez

Dissertations, Master's Theses and Master's Reports - Open

Wind energy has been one of the most growing sectors of the nation’s renewable energy portfolio for the past decade, and the same tendency is being projected for the upcoming years given the aggressive governmental policies for the reduction of fossil fuel dependency. Great technological expectation and outstanding commercial penetration has shown the so called Horizontal Axis Wind Turbines (HAWT) technologies. Given its great acceptance, size evolution of wind turbines over time has increased exponentially. However, safety and economical concerns have emerged as a result of the newly design tendencies for massive scale wind turbine structures presenting high slenderness ratios …

Monitoring Damage Initiation And Growth In Composite Structures By Acoustic Emission Method, Kassahun Mekonnen Asamene

Dissertations

In this dissertation, acoustic emission technique is examined as candidate for monitoring the integrity of polymer matrix structural members. Acoustic emission technique has so far been largely limited to laboratory tests and field applications have been mostly limited to qualification tests of aerospace structures. The lack of quantitative indications of damage in composite structural members associated with the complex nature of damage in these materials has been a limiting factor. Generally, a number of failure modes operate simultaneously at a site of damage, and each of these failure modes generates a different type of acoustic emission signal. In addition, issues …

A Novel Ultrasonic Method To Quantify Bolt Tension, Jairo Andres Martinez Garcia

USF Tampa Graduate Theses and Dissertations

The threaded fasteners are one of the most versatile methods for assembly of structural components. For example, in bridges large bolts are used to fix base columns and small bolts are used to support access ladders. Naturally not all bolts are critical for the operation of the structure. Fasteners loaded with small forces and present in large quantities do not receive the same treatment as the critical bolts. Typical maintenance operations such tension measurements, internal stress checking or monitoring of crack development are not practical due to cost and time constrains. Although failure of a single non-critical fastener is not …