Blog Posts

#8 Northrop Grumman On-Site Visit

Published:October 28th, 2022
Category:Fall Semester
Photo After On-Site Visit

The site visit was a success, we were about to gather valuable advice from Northrop Grumman directors and engineers during our presentation, while also being provided an exclusive tour of the Northrop Grumman facility. We plan to implement all the comments we received to improve our prototype and presentation.

In preparation for prototype day on 11/15, we have compiled and ordered a list of off-the-shelf (OTS) electrical parts to start testing detector methods. Capacitance sensing is the primary detection method we are designing based on the results from our design matrix. However, we did order some metal detection sensors to test if our findings were correct during our literature review. The ordered electrical parts are expected to be delivered next week.

Testing RC & Colpitts Oscillator Circuit
Iterations of the Circuit Design (right-side is still in development)

With the electrical components we had on hand, we assembled a capacitance sensing circuit consisting of a Colpitts oscillator and an RC oscillator with smoothing circuity. However, during testing, we noticed a bunch of noise within our signal, causing the result to be unreadable. The noise is most likely due to the low capacity of the oscilloscope unit.

Next week, we have scheduled a meeting with Dr. Orazem to discuss impedance as a detection method. We are also developing multiple body design concepts for our prototype, so we are not limited to one design. Come back next week to see what we have in store for our prototype design.

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#7 Eddy Current Testing

Published:October 21st, 2022
Category:Fall Semester

As we prepare for the on-site PDR presentation, which Northrop Grumman confirmed for Monday (10/24), we are continuing to test and collect data for possible detection methods. Methods we focused on this week were Eddy currents and capacitance. A paint thickness gauge, which is highly used in the automotive industry to measure the thickness of the paint of the outer body, was used to measure eddy currents to calculate the thickness on our test samples. From the experiment, we were able to see a noticeable difference between the thickness of the non-defect section to the defect section on both unidirectional and woven carbon fiber prepreg.

Testing samples using a paint thickness gauge
Colpitts oscillator with RC oscillator

To improve our capacitance measurement method that we have been testing for the past few weeks, we refined the circuit to include a Colpitts oscillator in addition to the RC oscillator. By incorporating a Colpitts oscillator, we are able to generate our own signal.

Our plans for next week are to perform EIS measurements with Dr. Orazem to determine the feasibility of the detection method, a literature review on Eddy current sensing, and begin prototype design based on site visit feedback.

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#6 Preparation of PDR Presentation

Published:October 14th, 2022
Category:Fall Semester
Meeting with graduate students
Pulse Echo Testing

Lots of testing has happened since we last posted. At the beginning of the week, Dr. Peter Ifju introduced us to his graduate students, who had experience with non-destructive testing (NDT) methods like ultrasonic transducers. The graduate students were kind enough to lend us their (Pulse Echo Ultrasonic Piezoelectric Transducer) equipment to test our sample prepreg layup with defects. While testing, we noticed some flaws in ultrasonic sensing methods. Some negatives of ultrasonic sensing based on the test were the requirement of the sensor to be stationary while collecting data and the scattering/attenuation of the acoustic waves when measuring through the composite fibers.

Instead of a traditional in-class lecture this week, we were given the opportunity to practice our PDR presentation in front of fellow classmates. Through this experience, we gathered helpful feedback from classmates to improve our presentation slides and approach. After implementing the suggestions from students’ feedback, we feel more prepared for our on-site presentation with our sponsor.

Soldered Capacitor
RC Oscillator Circuit
Capacitance Circuit Setup

We also visited the Herbert Wertheim Laboratory for Engineering Excellence (HWLEE) Prototyping Lab to create an RC oscillator circuit. However, we could not produce a signal generator due to the equipment’s bandwidth limitations. In the coming weeks, we plan on continuing testing on the RC circuit, conducting a literature review on shearography, and redesigning the device concept due to the lack of the roller in the layup process (based on recent info from the sponsor).

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#5 Testing, Testing, & more Testing

Published:October 7th, 2022
Category:Fall Semester
DIY parallel plate capacitor
Testing EIS on known capacitor

With the PDR deadline approaching,  we dedicated this week to test all the potential detection methods. We eliminated optical laser detection earlier in the week because carbon fiber was too absorbent to identify any intrusions’ reliability. From the equipment we were able to access and know how to use, we were able to design a DIY parallel plate capacitor and electrochemical impedance spectroscopy (EIS) device to test capacitance sensing methods of detection.

Since most of the methods we are testing are highly specialized in electrical engineering, we seek the help of Dr. Erin Patrick. During our meeting with Dr. Patrick, we discussed simple capacitive measurement methods with pulsed current or voltage sources that we can easily integrate into a simple portable device. We were then introduced to Dr. Mark Orazem to get more insight and help with EIS measurements of sample prepreg with and without defects to understand the capacitive nature of the systems better.

Applying plastic film to the metal surface
Rolling out prepreg with red defects
Final setup (left in the freezer to not cure)

At the end of the week, we constructed a preliminary test experiment with unidirectional and woven prepreg (half side with the defect and half with no defect). We would like to thank Dr. Peter Ifju (our coach) for supplying us with the prepreg material for this experiment. Next week we plan on creating a product architecture, finishing the PDR report, narrowing down detection methods due to budget constraints, and continuing lab testing of capacitance sensing methods.

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#4 First Month Report with Hurricane Ian

Published:October 1st, 2022
Category:Fall Semester
Hurricane Ian entering Florida

Hope everyone is staying safe from hurricane Ian this week. Even though this school week has been cut in half, we were able to complete and submit our first-month report containing the following:

  • Introduction
    • Project Objectives
    • Design and Prototype Expectations
  • Literature Review
    • Homomorphic Filtering
    • Non-contact Ultrasonic Inspection
    • Co-Planar Array Capacitive Sensing
  • Preliminary Product Design Specifications
    • Interactions Diagram
    • House of Quality
    • Technical Performance Measure
  • Concept Generation
    • Concept Matrix (Capacitive, Metal Detection, Thermal Imaging Optical, Ultrasonic)
  • Project Roadmap – Fall Semester

The list above only shows broadly what we wrote about. The full table of contents can be found in the report. This first month’s report is mainly used to prepare our team for the preliminary design review (PDR) on the week of October 17th with our sponsor, Northrop Grumman. We plan on continuing concept generation in the coming weeks and constructing our preliminary design report.

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#3 Concept Generation

Published:September 23rd, 2022
Category:Fall Semester
In-class concept generation activity
Birefringence idea from Dr. Ifju during coach meeting

This past week, we narrowed our solution pool to ultrasonic, capacitance, and metal detection devices after discussing with our coach and liaison engineers. We plan to determine each method’s feasibility through intensive research and determine the best form of implementing the device into Northrop Grumman’s composite manufacturing process.

Currently, we are constructing a detailed road map to give us a better visualization of project completion. In the coming weeks, we plan on doing the following:

  • Deliver our first monthly report to detail progress and project direction
  • Northrop Grumman site visit
  • Acquire pre-preg material for future testing

We also plan on presenting our project design report to Northrop Grumman on the week of October 17th. We are super excited about how things are rolling and hope to see you next week on our blog!

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#2 First In-Class Presentation

Published:September 16th, 2022
Category:Fall Semester
Photo after in-class IPPD Presentation
Tour of Dr. Ifju’s Composite Lab

From the last blog post, we have made some slight modifications to our logo, met our liaison engineers for the first time, presented our logo & problem to the IPPD class, and done some preliminary research on possible physic solutions for our project. In addition, each individual on the team researched “what is prepreg” and “what the processes are to layup prepreg” to understand prepreg use in the industry better.

We also met with our coach, Dr. Peter Ifju, for the 2nd time and received many great pointers that were able to narrow down our possible solutions. After our meeting, the coach gave the team a tour of his composite lab, where we could see how prepreg is stored and physically interact with the prepreg with the backer material. Through this hands-on experience with the prepreg, we were able to confirm/eliminate solutions we had in mind.

Next week, we plan on developing additional project goal specifications, research material characterization techniques, and their interaction with carbon fiber as potential solutions.

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