Mechanical Engineering Commons^™

Numerical Evaluation Of Energy Release Rate At Material Interfaces For Fatigue Life Predictions, Robert L. Hendrickson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Composite materials are becoming popular in almost all industries. Carbon-fiber and glass-fiber composites are used in aircraft, sports equipment, boats, prosthetics, and wind turbine blades. In all these applications, the composites are subjected to different loads. Loads can take the form of impact or cyclic/fatigue loading, both of which decrease the strength of composites as micro-cracks grow through the composite. Composite laminates are made up of fiber plies (thin layers of fiber) and the fibers are surrounded by a resin like epoxy. It is common for laminates to fail because of delamination growth (plies peeling apart). Small delaminations do not …

Effect Of Manufacturing Processes On The Loss Factor And Other Mechanical Properties Of Kenaf Fiber-Reinforced Composites, Brian P. Spackman

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The characteristics essential for manufacturing parts and products are not well known for natural fiber-reinforced composite materials. Natural fibers display properties similar to glass fibers, and present a more environmentally friendly option for manufacturing composite materials. This research investigates various parameters in the manufacture of kenaf fiber-reinforced composites including cure time, density, matrix hardener ratio, surface treatment, and fiber length and examines the effect they have on mechanical properties of the composite material. Several samples were created and subjected to a vibrational test. Using known relationships, mechanical properties were extracted from the test results. Samples were found to exhibit repeatable …

Fabrication Of Multi-Material Structures Using Ultrasonic Consolidation And Laser-Engineered Net Shaping, John Olorunshola Obielodan

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

This research explores the use of two additive manufacturing processes for the fabrication of multi-material structures. Ultrasonic consolidation (UC) and laser- engineered net shaping (LENS) processes were used for parallel systematic investigations of the process parameters and methodologies for the development of multi-material structures.

The UC process uses ultrasonic energy at low temperature to bond metallic foils. A wide range of metallic materials including nickel; titanium; copper; molybdenum; tantalum; MetPreg®; silver; stainless steel; and aluminum alloys 1100, 3003, and 6061 were bonded in different combinations. Material domains are inherently discrete in ultrasonically consolidated structures. The mechanical properties of some of …

Axisymmetric Finite Element Modeling For The Design And Analysis Of Cylindrical Adhesive Joints Based On Dimensional Stability, Paul E. Lyon

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The use and implementation of adhesive joints for space structures is necessary for incorporating fiber-reinforced composite materials. Correct modeling and design of cylindrical adhesive joints can increase the dimensional stability of space structures. The few analytical models for cylindrical adhesive joints do not fully describe the displacement or stress field of the joint.

A two-dimensional axisymmetric finite element model for the design and analysis of adhesive joints was developed. The model was developed solely for the analysis of cylindrical adhesive joints, but the energy techniques used to develop the model can be applied to other types of joints as well. …