Effects And Characteristics Of Molybdenum Disilicide Jacketed Waveguides On The Strength And Efficiency Of Structural Integrity Fields
Title
Midshipman, USS Charon, RSV-88003
Abstract
Structural integrity fields (SIFs) provide increased structural strength to starships. Making improvements on this technology can be difficult due to its cross-compatibility with other ship systems. One area where improvements could be made is the coating for the SIF network waveguides. Molybdenum disilicide (MoSi2) was identified as a potential replacement for the molybdenum coating currently in use. In the experiment, MoSi2resulted in higher tensile and compressive strengths, lower energy usage, and a decrease in shearing strength.
Introduction
Inside each Starfleet starship is a skeleton of tritanium, duranium, and terminium trusses. These materials are preferable for starship construction due to their physical characteristics. Yet, none of these materials can stand up to the rigors of interstellar travel on its own. The propulsive and gravitational forces experienced during space travel far exceed the structural limits of these materials. Likewise, some ships are so massive that they risk collapsing in on themselves under their own weight without some sort of support.
To compensate for these limitations, starships supplement their mechanical strength with a structural integrity field system (SIF). The SIF directs forcefield energy into a network of ceramic-polymer conductive elements within the spaceframe. This has the effect of increasing the load bearing capacity of the structure by up to 125 times its normal strength. Starship builders have used the technology behind structural integrity fields for over a century. In that time, little has changed in the design of these systems. Graviton polarity sources feed into 250 millicochrane subspace fields distortion amplifiers before passing into a network of molybdenum jacketed triphasic waveguides. These waveguides run alongside the trusses and distribute the forcefield energy into the ceramic-polymer conductive elements via conductive tritanium rods. In addition to the spaceframe, the ship's external shell is also laced with a secondary SIF network to provide more resilience.
Because of its importance, the SIF network contains multiple redundant generators. It is not uncommon for different generators to be powering separate sections of a ship at any given time. Deflector shields and tractor beams also use similar power sources. This means that extra generators provide a net benefit to the ship. The overlapping systems allow engineers in the field to reroute power between them as needed. Any changes made to the SIF generators for the sake of efficiency could potentially disrupt this symbiosis. Substantial changes could even rule out their use as redundant systems for other important ship systems.
Efficiency improvements to the SIF network need to be limited to subsystems that do not interact with other systems. Waveguides are one such subsystem, distributing forcefield energy through the network to ceramic-polymer conductive elements within the spaceframe. They are rectangular conduits with a broad wall width of 2.3cm and a height of 0.85cm. The sizing of the waveguides is important because it determines the frequency of energy that can travel through them. The current size corresponds to a transmittable frequency between 8.147 Ghz and 12.318 Ghz. This covers the nominal frequency range output by the subspace field distortion amplifiers. Changes to the size of the waveguides would also necessitate replacement of the amplifiers, which would not be ideal.
This leaves the molybdenum coating on the waveguides as a remaining avenue for improvement. Molybdenum (Mo) is a diagravitic material, making it perfect for use in waveguides. It has the added benefit of having a melting temperature of 2623 °C and an extremely low coefficient of thermal expansion. The molybdenum coating on the waveguides allows forcefield energy to circumvent the inverse square law, travelling through the network with minimal loss.
While molybdenum appears to be perfect for waveguide coating, it is also the perfect place to make improvements. One such improvement may be to switch from molybdenum to molybdenum disilicide. Molybdenum disilicide (MoSi2) is an intermetallic compound created through the combination of molybdenum and silica. The compound has a lower melting temperature than molybdenum, 2030 °C, but retains its low coefficient of thermal expansion. More importantly, the addition of silica increases the material’s gravitic permittivity. This suggests that molybdenum disilicide could make an excellent candidate to replace molybdenum as a coating for structural integrity field waveguides.
This work attempts to improve the efficiency and strength of structural integrity fields by replacing molybdenum with molybdenum disilicide as a coating for the waveguides. This paper presents the characteristics of these experimental waveguides along with a side-by-side analysis of their performance with standard waveguides in terms of energy use and structural strength.
Procedure
Three test conditions were identified in designing this experiment. The first was a baseline test with no structural integrity field present. The goal of this test was to get a baseline for the inherent strength of the materials chosen for the experiment. The second was a control test using a powered structural integrity field with a standard molybdenum jacketed waveguide. The third was an experimental test using a powered structural integrity field with a molybdenum disilicide jacketed waveguide.
Each condition needed to be subjected to the normal forms of stress placed upon the structural members of a starship. To measure tensile, compressive, and shearing strength, three separate trials would be required. Due to the destructive nature of these trials, nine models would be needed to test all of the conditions.
Nine models of a typical secondary spaceframe support were created for this experiment. The models were pared down to only consist of the materials necessary to create and sustain a structural integrity field. Nine identical microextruded aluminium i-beams were fabricated with a dimension of 6 cm x 9 cm x 1 m, with a 1 cm thick flange and 1 cm web thickness. Aluminium was chosen as a test material due to its softness, having a mere 2.75 on the Mohs hardness scale. This decision reduced the amount of force needed to perform structural tests, making it possible to perform the testing within a traditional lab setting. Ceramic-polymer elements were phase bonded to each i-beam as per Star Fleet construction standards. Nine tritanium rods, spaced at 10 cm intervals, conduct the forcefield energy from the waveguides to the conductive ceramic-polymer elements.
In the three baseline and three control models, a single triphasic waveguide with a broad wall width of 2.3cm and a height of 0.85cm was coated with molybdenum before being gamma welded onto the structure. In the experimental models, a waveguide of identical dimensions was coated with molybdenum disilicide prior to its attachment to the model. All of the waveguides run the full length of their respective i-beam.
To compensate for the smaller size of the models, the structural integrity field was powered by a graviton polarity source connected to a 2 nanocochrane subspace field distortion transformer. The output was then routed through a graviton field detector before being attached to one end of the waveguide. The opposite end was connected to a second graviton field detector to measure the amount of forcefield energy used by the field.
Trials were conducted within a holodeck, where shaped forcefield emitters could apply measured amounts of force to the models. For each trial, the graviton polarity source was powered on. Graviton field detectors then took measurements for one minute without any physical stresses being placed on the model to establish a baseline for energy usage. The baseline energy drain rate (EDRvB ), measured in nanocochranes, was calculated from the average pre-model energy rate (Φi) and average post-model energy rate (Φe) using the formula,
EDRb= Φi − Φe
Next, holodeck forcefield emitters applied an increasing amount of force, in the manner specific to each trial. Photonic extensometers registered the deformation of the i-beams and marked the transition from the model’s elastic behavior, where the material was capable of returning to its previous shape, to a plastic one, where the material would hold its new, deformed shape. At the presence of this transition, sensors logged the amount of force being generated applied, measured in megapascals, as the material’s yield strength (Fty). The forcefield emitters then continued exerting force until the point of complete structural failure, which sensors logged, also in megapascals, as the model’s ultimate tensile strength (Ftu).
As the models were put under stress, the graviton field sensors continued to monitor energy usage. After a complete structural failure of a model, the graviton field detectors calculated and reported the maximum energy drain rate (EDRmax) experienced during the experiment using the same energy drain rate formula listed above.
Nine trials were devised for this experiment. Three stress trials were performed for each of the three test conditions. The details of each trial are listed in table 1. For each condition, models were subjected to a tensile, compressive, and shearing strength test. The tensile strength trials involved applying outward force to the ends of the longest axis of the model, pulling the ends away from each other. For the compressive strength tests, inward forces were applied to the model along its longest axis, pushing the ends toward each other. For the shearing strength test, the model was subjected to a force perpendicular to and in the center of its longest axis.
| Trial | Waveguide Jacketing | Structural Integrity Field | Stress Test |
|---|---|---|---|
| Tut | Mo | Unpowered | Tensile |
| Tuc | Mo | Unpowered | Compressive |
| Tus | Mo | Unpowered | Shearing |
| Tct | Mo | Powered | Tensile |
| Tcc | Mo | Powered | Compressive |
| Tcs | Mo | Powered | Shearing |
| Tet | MoSi2 | Powered | Tensile |
| Tec | MoSi2 | Powered | Compressive |
| Tes | MoSi2 | Powered | Shearing |
Table 1: List of trials and their conditions
In all trials, powered models were expected to have an increase in strength of at least 120 to 130 times their unpowered counterparts. The molybdenum disilicide models should have exhibited an increase in strength over their molybdenum counterparts. The difference in the two materials’ gravitic permittivity suggests a potential increase in strength between 2% to 5%. Additionally, significant differences in the amount of energy used by the models, both at rest and under stress, should have been registered. Again, the molybdenum disilicide coated models were expected to outperform the molybdenum models.
Results
For the baseline trials, tensile and compressive tests resulted in an average yield strength of 34.55 MPa and an average ultimate tensile strength of 89.67 MPa. The shear strength test resulted in a lower yield strength of 18.98 MPa and ultimate tensile strength of 58.24 MPa, following von Mises yield criterion. The baseline energy drain rate for the models was an average of 0.354 nanocochranes (nCo). A maximum energy drain rate was not calculated for the baseline condition as the models’ structural integrity fields were not powered during their trials.
The control model tensile and compressive tests resulted in an average of 4.24 gigapascals (GPa). The ultimate tensile strength of these trials measured an average of 11 GPa. The structural integrity fields gave a respective 122.74% and 122.67% increase in strength from the baseline trials. Shearing yield strength was 2.28 GPa, a 120.13% increase. Shearing ultimate tensile strength was 7.05 GPa, an increase of 121.05%. Baseline energy rates were in line with the unpowered test, with an average of 0.355 nCo. The average maximum energy drain rate logged by the graviton field detectors was 1.631 nCo.
For the experimental condition, the average yield strength for the tensile and compressive trials was 4.39 GPa. The ultimate tensile strength for these trials averaged 11.38 GPa. These correspond to a respective increase of 127.06% and 126.9% from the baseline. It also shows an increase in yield strength and ultimate tensile strength of 3.5% from the control condition. The shearing stress trial resulted in a yield strength of 2.23 GPa and an ultimate tensile strength of 6.93 GPa. This is an increase of 117.49% and 118.99% from baseline, respectively. There was a decrease in yield strength and ultimate tensile strength of 2.19% and 1.7% respectively from the control condition. The baseline energy drain rate averaged 0.327 nCo, showing a 7.72% drop in energy usage from the control conditions. The average maximum energy drain rate was 1.619 nCo, showing a 0.08% decrease in energy usage from the control trial.
The full experimental results are listed in Table 2.
| Trial | Yield Strength (Fty) | Ultimate Tensile Strength (Ftu) | Baseline Energy Drain Rate (EDRb) | Maximum Energy Drain Rate (EDRmax) |
|---|---|---|---|---|
| Tut | 34.56 MPa | 89.65 MPa | 0.356 nCo | N/A |
| Tuc | 34.56 MPa | 89.68 MPa | 0.354 nCo | N/A |
| Tus | 18.98 MPa | 58.24 MPa | 0.353 nCo | N/A |
| Tct | 4.24 GPa | 10.99 GPa | 0.355 nCo | 1.631 nCo |
| Tcc | 4.24 GPa | 11.01 GPa | 0.356 nCo | 1.633 nCo |
| Tcs | 2.28 GPa | 7.05 GPa | 0.353 nCo | 1.629 nCo |
| Tet | 4.34 GPa | 11.37 GPa | 0.327 nCo | 1.618 nCO |
| Tec | 4.43 GPa | 11.38 GPa | 0.328 nCo | 1.621 nCO |
| Tes | 2.23 GPa | 6.93 GPa | 0.325 nCo | 1.617 nCo |
Table 2: Results from the experiment
Conclusions
The results show that molybdenum disilicide coated waveguides have some advantages and disadvantages. The 7.72% drop in energy usage seen in the experiment could be useful when scaled to a starship’s full size. A power reduction of that magnitude would give engineers on ships retrofitted with these changes more power to dedicate to other systems that use similar power sources. In new ships, the number of generators necessary to power the structural integrity field could be reduced, opening up space in the hull for other systems. While the increase of 3.5% in both tensile and compressive strength sounds promising, the decrease in shearing stress requires some serious consideration. Tensile and compressive strength are most commonly experienced by starships at flight. As the ship moves through space it faces stresses as it is stretched and compressed by the forces of its own engines. Starship design takes this into account and some of the stresses are offset through the layout of the spaceframe. Shearing stresses are more commonly experienced when the ship makes contact with a foreign body. While shielding normally prevents objects from making contact with the hull, collisions do happen. Decreasing the shearing strength of the ship could potentially lead to more catastrophic failures and greater loss of life.
A number of issues need to be studied prior to making any changes to the existing systems. Tests with terminium, tritanium, and duranium models are necessary to fully test the feasibility of these changes. These tests will require specialized equipment unavailable to the author at this time, and may have different results due to the physical characteristics of those materials. Larger scale testing would also need to take place to ensure that the gains experienced in the smaller models scale appropriately. Many of these tests could be performed in simulations, but it is the author’s opinion that they be tested in real world conditions before installation on existing ships. What the small scale experiments, such as this one, prove is that there are still many gains to be made both in the efficiency and the strength of these systems.
