Mechanical Engineering Commons^™

Cfrp Delamination Density Propagation Analysis By Magnetostriction Theory, Brandon Eugene Williams

All Dissertations

While Carbon Fiber Reinforced Polymers (CFRPs) have exceptional mechanical properties concerning their overall weight, their failure profile in demanding high-stress environments raises reliability concerns in structural applications. Two crucial limiting factors in CFRP reliability are low-strain material degradation and low fracture toughness. Due to CFRP’s low strain degradation characteristics, a wide variety of interlaminar damage can be sustained without any appreciable change to the physical structure itself. This damage suffered by the energy transfer from high- stress levels appears in the form of microporosity, crazes, microcracks, and delamination in the matrix material before any severe laminate damage is observed. This …

A Novel Approach For Real-Time Quality Monitoring In Machining Of Aerospace Alloy Through Acoustic Emission Signal Transformation For Dnn, David Adeniji, Kyle Oligee, Julius Schoop

Mechanical Engineering Faculty Publications

Gamma titanium aluminide (γ-TiAl) is considered a high-performance, low-density replacement for nickel-based superalloys in the aerospace industry due to its high specific strength, which is retained at temperatures above 800 °C. However, low damage tolerance, i.e., brittle material behavior with a propensity to rapid crack propagation, has limited the application of γ-TiAl. Any cracks introduced during manufacturing would dramatically lower the useful (fatigue) life of γ-TiAl components, making the workpiece surface’s quality from finish machining a critical component to product quality and performance. To address this issue and enable more widespread use of γ-TiAl, this research aims to develop a …

A Novel Approach For Real-Time Quality Monitoring In Machining Of Aerospace Alloy Through Acoustic Emission Signal Transformation For Dnn, David Adeniji, Kyle Oligee, Julius Schoop

Mechanical Engineering Faculty Publications

Gamma titanium aluminide (γ-TiAl) is considered a high-performance, low-density replacement for nickel-based superalloys in the aerospace industry due to its high specific strength, which is retained at temperatures above 800◦C. However, low damage tolerance, i.e., brittle material behavior with a propensity to rapid crack propagation, has limited the application of γ-TiAl. Any cracks introduced during manufacturing would dramatically lower the useful (fatigue) life of γ-TiAl components, making the workpiece surface’s quality from finish machining a critical component to product quality and performance. To address this issue and enable more widespread use of γ-TiAl, this research aims to develop a real-time …

In-Situ Characterization Of Surface Quality In Γ-Tial Aerospace Alloy Machining, David Adeniji

Theses and Dissertations--Mechanical Engineering

The functional performance of critical aerospace components such as low-pressure turbine blades is highly dependent on both the material property and machining induced surface integrity. Many resources have been invested in developing novel metallic, ceramic, and composite materials, such as gamma-titanium aluminide (γ-TiAl), capable of improved product and process performance. However, while γ-TiAl is known for its excellent performance in high-temperature operating environments, it lacks the manufacturing science necessary to process them efficiently under manufacturing-specific thermomechanical regimes. Current finish machining efforts have resulted in poor surface integrity of the machined component with defects such as surface cracks, …

Acousto-Ultrasonic Shm/Nde Methods Toward Field Application, Stephen Harris Howden

Theses and Dissertations

Acousto-ultrasonic nondestructive evaluation (NDE) and structural health monitoring (SHM) methods offers solutions in damage detection, material properties evaluation and more. These ultrasonic waves can propagate through solids and interact with structural features and discontinuities. In this thesis use of several acousto-ultrasonics NDE/SHM methods were explored to evaluate their sensing and detection capabilities toward damage detection field applications in nuclear and aerospace industries.

For nuclear applications, passive sensing using piezoelectric sensors and acoustic emission (AE) techniques were explored on the spent fuel dry storage casks. Dry storage casks are used in the nuclear industry to transport or store spent nuclear fuel …

Material State Awareness For Composites Part Ii: Precursor Damage Analysis And Quantification Of Degraded Material Properties Using Quantitative Ultrasonic Image Correlation (Quic), Subir Patra, Sourav Banerjee

Faculty Publications

Material state awareness of composites using conventional Nondestructive Evaluation (NDE) method is limited by finding the size and the locations of the cracks and the delamination in a composite structure. To aid the progressive failure models using the slow growth criteria, the awareness of the precursor damage state and quantification of the degraded material properties is necessary, which is challenging using the current NDE methods. To quantify the material state, a new offline NDE method is reported herein. The new method named Quantitative Ultrasonic Image Correlation (QUIC) is devised, where the concept of microcontinuum mechanics is hybrid with the experimentally …

Physics Based Modeling Of Guided Waves For Detection And Characterization Of Structural Damage In Nde And Shm, Banibrata Poddar

Theses and Dissertations

Guided waves based damage detection techniques are popular for their ease of generation and detection along with their ability to travel long distances. Accurate and efficient modeling is a key for successful implementation of guided waves for NDE/SHM. However, efficient prediction of scattering from various damage is challenging due to the complex nature of these guided waves.

This dissertation presents as physics based efficient and accurate modeling techniques to predict ultrasonic wave propagation and their interaction with various damage. Detection and characterization of damage in structures can typically be divided into two categories, active and passive. This research is aimed …

Damage Tolerance And Assessment Of Unidirectional Carbon Fiber Composites, Mark David Flores

Open Access Theses & Dissertations

Composites are beginning to be used in a variety of different applications throughout industry. However, certification and damage tolerance is a growing concern in many aerospace and marine applications. Although compression-after-impact have been studied thoroughly, determining a damage tolerance methodology that accurately characterizes the failure of composites has not been established. An experimental investigation was performed to study the effect of stacking sequence, low-velocity impact response, and residual strength due to compression and fatigue. Digital Image Correlation (DIC) captured the strains and deformation of the plate due to compression. Computational investigations integrated non-destructive techniques (C-Scan, X-Ray) to determine the extent …

Resonance Testing For Fault Detection Of Steam Generator Heat Transfer Tubing Walls, Michael C. Shannon, John Howington, Jesus Sanchez, Colin Sandidge, Jeremy Townsend, Keith Welsh

Chancellor’s Honors Program Projects

No abstract provided.

Structural Health Monitoring With Piezoelectric Wafer Active Sensors--Predictive Modeling And Simulation, Victor Giurgiutiu

Faculty Publications

This paper starts a review of the state of the art in structural health monitoring with piezoelectric wafer active sensors and follows with highlighting the limitations of the current approaches which are predominantly experimental. Subsequently, the paper examines the needs for developing a predictive modeling methodology that would allow to perform extensive parameter studies to determine the sensing method’s sensitivity to damage and insensitivity to confounding factors such as environmental changes, vibrations, and structural manufacturing variability. The thesis is made that such a predictive methodology should be multi-scale and multi-domain, thus encompassing the modeling of structure, sensors, electronics, and power …

Structural Health Monitoring With Piezoelectric Wafer Active Sensors—Predictive Modeling And Simulation, Victor Giurgiutiu

Faculty Publications

This paper starts a review of the state of the art in structural health monitoring with piezoelectric wafer active sensors and follows with highlighting the limitations of the current approaches which are predominantly experimental. Subsequently, the paper examines the needs for developing a predictive modeling methodology that would allow to perform extensive parameter studies to determine the sensing method’s sensitivity to damage and insensitivity to confounding factors such as environmental changes, vibrations, and structural manufacturing variability. The thesis is made that such a predictive methodology should be multi-scale and multi-domain, thus encompassing the modeling of structure, sensors, electronics, and power …

Characterization Of Crack Propagation During Sonic Ir Inspection, Jacob Kephart, John Chen, Hong Zhang

Mechanical Engineering

Sonic IR is an emerging, thermal-based, nondestructive evaluation (NDE) technique. Typically a short burst of high power acoustical energy is injected into an object being studied and certain types of defects heat up and is detected using a thermal imaging camera. This inspection technique is very fast, lasting only a few seconds for total inspection time. However due to many uncertainties in the inspection process it has yet to be adopted widely by industry. There are many unknown parameters governing sonic IR, which need to be understood before it becomes a widely used NDE technique. This paper shows that under …