Date of Award

2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Civil Engineering

Subject(s)

Storage tanks--Impact testing., Honeycomb structures., Strength of materials.

Abstract

Within the civil engineering industry, the evaluation of a retro-fit system or more- specifically, a post-installed, glass fiber reinforced polymer and honeycomb system over steel is evaluated on how this retro-fit system can help minimize impact and critical kinetic energy onto steel storage tanks caused from wind-borne debris to structures in hurricane prone regions. Determining an accurate formula for critical kinetic energy for steel has also been an on-going process in our industry for over 200 years. This research helps to get one-step closer to accurately determining a valid equation. Existing theories and equations of critical kinetic energy have been evaluated and compared to the laboratory data within. The major type of laboratory testing performed was impact testing, using guidelines of the Department of Energy Protocol. Two other minor laboratory tests were performed to correlate the data for comparison. One finite element analysis was also evaluated for correlation. Laboratory testing was performed on four (4) stainless-steel panels consisting of one, un-reinforced panel and three reinforced panels. These panels were tested using the Department of Energy Protocol 5 at Texas Tech University (TTU) for impact testing of the panels. The same laboratory samples of iv honeycomb and epoxy were tested at the University of Alabama Huntsville (UAH). The honeycomb and epoxy samples consisted of 4”x4” coupons for 1/8” and 1⁄4” honeycomb cell size. These were assembled in accordance with the same laboratory impact procedure and tested for compression and deflection was measured. Assembly was performed in accordance with HJ3’s manufacturer recommendations and specifications as well as the same lay-up pattern consisting of 1-layer of honeycomb, 2-layers and 3- layers. Laboratory tests were performed at UAH on the glass fiber reinforcement material and the epoxy. This test sample consisted of 16”x16” indention panels using 1/8” density cell honeycomb and the layup was the same. The last analysis consisted of a finite element modeling (FEM) of the honeycomb core for the 1⁄4” panel using the software Abaqus VER.6.8-4. This sample was assembled in the same fashion as the laboratory impact test panels. Finally, Theoretical critical kinetic energy of the panels was evaluated using the empirical formulas, Neilson’s formula, SRI’s formula, Greenstreet’s formula and Linderman’s equation of load to relate to deflection. Gerard’s theory of adding protective layers to reduce critical kinetic energy appear to be valid. A configuration of thickness varies for amount of energy to be absorbed. SRI’s formula appears to be the most accurate at this date and time. The sample laboratory test performed at UAH were evaluated and the measured deflection was compared to the empirical deflection and load, using the laboratory data and Kunimoto and Yamada’s formula [40]. In general, it was determined that the honeycomb post installed system may absorb approximately 5.7 percent to 10.3 percent of critical kinetic energy depending on the density of the honeycomb and approximately 1.5 percent to 60.5 percent deflection depending on the number of layers or height of the honeycomb.

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