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Figure 1. This picture displays the orientation of the PVC meta-materials prior to experimentation
Varying the Constituents of Meta-materials to Improve Efficiency Jeff Bang
Rockdale Magnet School for Science and Technology
Figure 2. This picture displays the finished meta-material.
Introduction
Purpose
Hypothesis
Pictures
Is it possible to stop an earthquake? Several million earthquakes occur in the world each year. Out of those, only about 20,000 earthquakes are identified. Last year, there have been 4086 earthquakes worldwide causing 113 deaths. Research on how to prevent earthquakes from causing death and destruction is a main focus in society today.
Maintaining the safety of lives is critical since earthquakes are one of the most devastating natural disasters; prevention of deaths would save many lives. Meta-materials are the most current method researched in dissipating earthquake waves. This technology has the potential to reduce the severe effects of catastrophes such as the 1906 San Francisco Earthquake.
The research hypothesis for this project states that if different materials are used to construct meta-materials, then it will have a significant effect on the meta-materials efficiency.
The purpose of this project is to test different materials to determine its effects on the meta-materials’ efficiency.
Methodology
Experimental Design Diagram
In this project, there are three independent variables. There are three different materials that will be tested: PVC, wood, and concrete. These materials will be created as meta-materials and tested. They will be compared to an experiment without any meta-materials. This is so that the data can be compared to see how effective the different materials will be as meta-materials. They will be tested at eight different frequencies: 100 Hz, 200 Hz, 300 Hz, 400 Hz, 500 Hz, 1000 Hz, 1500 Hz, and 2000 Hz with three trials each.
The dependent variable of this project is the acceleration of earthquake vibrations/amplitude. The actual vibration that will be measured will be the ones that exist after they have passed through the meta-materials when they read the model building and the 1-axis accelerometer that is mounted to it. The unit of measurement is meters per second per second.
Title: Varying the Constituents of Meta-materials to Improve Efficiency
Hypothesis: If different materials are used to construct meta-materials, then it will have a significant effect on the meta-materials’ efficiency
IV: Different constituents of meta-materials; frequency
DV: Acceleration (m/s/s)
Constant: Loud Speaker, 1-Axis Accelerometer, Frequency, 17.1kg of dirt, 37x24x28cm box, Model Building, position of meta-materials
Figure 7. This picture displays the experimental setup.
Background Information
Level of IV
None
PVC
Wood
Concrete
Frequency
100 Hz
3 Trials
200 Hz
300 Hz
400 Hz
500 Hz
1000 Hz
1500 Hz
2000 Hz
Earthquakes destroy buildings by weakening and breaking the supports of the building (Why buildings respond differently…, 2011). Taller, narrower buildings can withstand a higher frequency better than a building with short, wide dimensions. This is because high frequency waves have short waves, which affects the building less. A low frequency wave has long, low waves. This affects a tall narrow building much more than a short, wide building. The null hypothesis is that if meta-materials surround a building, then they will not have a significant effect of earthquake protection for the building
In doing this project, there are certain terms that require some prior knowledge. Some of these are meta-materials, seismic waves, and earthquake. Meta-materials are materials engineered to have optical, thermal, or other specific properties that naturally occurring substances do not. These materials can block, bend, and manipulate all sorts of waves. Meta-materials were first discovered in 1986 by a Russian theorist, Victor Veselago. Meta-materials work mostly because of their shape. The material used to make meta-materials does not have a huge impact on the functionality of the meta-material itself. The only conditions are that it must be strong enough to withstand seismic waves and be made of different materials than what it surrounds. Seismic waves are waves of energy that are mainly caused by earthquakes. The waves are caused by a sudden breaking of rock in the earth or an explosion. Seismic waves are recorded by seismographs when they are travelling through the earth. Earthquakes occur when a fault moves in the Earth, causing waves of energy to go outward from the fault.
The materials used to build the meta-materials are Polyvinyl Chloride (PVC) pipes, wood, and concrete. PVC pipes can be easily obtained from a hardware store. These are used because it can easily be replaced and adjusted for the meta-materials for function correctly. Wood can be obtained from the hardware store and can be used to easily create the meta-materials needed for this research project. Concrete can be easily obtained as well and can also be easily used to create specific shapes and sizes using molds.
Figure 8. This figure displays the power signal generator that was used for this experiment.
Data Analysis
Graph
After the experimentation, the accelerations were recorded. All of the data was inputted into MINITAB in order to obtain inferential and descriptive statistics. One ANOVA test was done on the variables of this experiment. The ANOVA test was done on the material and frequency variables, and the results showed that the meta-materials significantly reduced the acceleration of the mimicked seismic waves through the dirt (Materials DF: 2; F: ; P<0.05) (Frequency DF: 7; F: ; P<0.05). An ANOVA test was run on the average of the acceleration that resulted from the experiment data. It averaged the acceleration of frequencies per material.
The information gathered with the use of ANOVA testing and descriptive statistics showed that the research hypothesis was accepted. This is because the data of one material’s meta-material deviated from the data of another material’s meta-material. The null hypothesis was rejected.
Graph
Discussion & Conclusion
The purpose of this project is to test different materials to determine its effects on the meta-materials’ efficiency. From the data obtained, it is concluded that the research hypothesis was accepted (Materials DF: 2; F: ; P<0.05) (Frequency DF: 7; F:109.91; P<0.05). The null hypothesis was rejected. The research goal was achieved.
Figure 3 displays the Interval Plot of Acceleration, which shows the standard deviation of the data. As show in Figure 1, the data did not deviate much from the mean, especially accounting for the y-axis interval of Figure 5 displays the Chart of Mean of Acceleration for material per frequency. This chart graphed the average of the data for each trial per frequency per material. The general trend of the average acceleration of the concrete independent variable is the lowest compared to the average acceleration of the PVC and Wood independent variable, showing that the concrete independent variable was more effective in dissipating sound waves than the PVC and the wood independent variables.
Compared to other research, this project did follow the trend that meta-materials reduce the acceleration. However, the research it is compared to is a theoretical analysis and not an actual experimentation. For future research, the shape of the meta-materials could be tested as well as the material of the meta-materials.
Figure 3: This graph shows the standard deviation of the acceleration for each material..
Procedures
Construct Meta-materials (PVC, Wood, & Concrete)
Construct Model Building
Figure 5. This graph shows the average of the acceleration for each frequency per material.
No Meta-materials (100, 200, 300, 400, 500, 1000, 1500, 2000 Hz; 3 Trials)
Conduct Experiment
Wood Meta-materials
(100, 200, 300, 400, 500, 1000, 1500, 2000 Hz; 3 Trials)
Sources of Error & Limitations
Limitations to a more accurate data would be the possibility of human error when constructing the meta-materials. As the meta-materials had to be as precise as possible and they were built by hand, there was always the possibility for a human error. Another limitation was the inability to specify the exact frequency used for the experimentation. Figure 8 shows the function generator that was used in this experiment. The control used to set the frequency are dials and not numerical values, causing a possibility of wavering frequencies in between trials. A source of error in this research project could be that the positions of the meta-materials might have altered in between different variables, potentially affecting the acceleration measured.
Figure 4. This graph shows the percentage difference of the highest peak acceleration between the three materials per frequency.
PVC Meta-materials
(100, 200, 300, 400, 500, 1000, 1500, 2000 Hz; 3 Trials)
Concrete Meta-materials
(100, 200, 300, 400, 500, 1000, 1500, 2000 Hz; 3 Trials)
Figure 6. This graph shows the percentage difference of the average acceleration between the three materials per frequency.
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