1 DESIGNING INCLUSIVE, ERGONOMIC AND SAFE HYPERLOOP SEATING Balvinder Kaur Dhillon Eesha Ather Farah Ahmed Ali Dawoud Ria Ketan Chandarana 1 Biomedical Research Team Hyperlink, London, United Kingdom 07 th June 202 3 Abstract When deciding which material is the most appropriate to develop the Hyperloop pod out of, passenge r safety should be considered and at the best centre of the choice. This is due to the side effects of vacuum exposure which can occur if the pod were to develop and crack if it were to propagate. When designing the hyperloop material choice is very import ant and a material with a high tensile strength, among other material properties, is highly desirable. Within this paper, a literature review is conducted to delve deeper into the reasons why the correct material choice is vital, focusing on the biological aspects. Materials are then chosen so a literature review can then be conducted into these materials. COMSOL Multiphysics is then used to simulate these materials regarding their tensile strength within a vacuum to support the literature review where Car bon Fibre reinforced polymers are shown to be the most desirable material. 2 Table of Contents Abstract ________________________________ _______________ 1 Introduction ________________________________ ___________ 3 Literature Review ________________________________ _______ 4 1. Carbon Fibre Reinforced Polymers _____________________ 6 2. Aluminum ________________________________ __________ 8 3. Steel ________________________________ ______________ 9 4. Decision Matrix: ________________________________ ____ 11 Methodology ________________________________ __________ 13 1. Biological Impacts ________________________________ __ 13 2. Crack Formation ________________________________ ___ 14 3. Material Structure and CFRP _________________________ 14 Results ________________________________ _____________ 16 Simulation ________________________________ ___________ 16 1. Steel ________________________________ ____________ 17 1. Carbon Fibre Reinforced Polymers (CFRP) ______________ 19 2. Aluminum ________________________________ _________ 20 Discussion ________________________________ ___________ 21 C onclusion ________________________________ ___________ 25 Bibliography ________________________________ __________ 26 3 Introduction The Hyperloop is the next mode of transport that, when developed, can create socioeconomical changes and have great stride in science. Fundamentally, hyperloop utilises electromagnetic levitation and a vacuum to travel at 760mph [Babu C, 2021]. Within this paper we will specifically focus on the vacuum of hyperloop technolog y. Within a vacuum, there is no pressure and thus no air particles. As a result, when moving, the hyperloop pods do not encounter air particles resulting in less resistance, hence allowing it to move at such immense speeds. While the vacuum is highly advan tageous, it comes with many difficulties and challenges. These being the biological impacts, the important of material selection and the problem of disembarking and embarking passengers among other things. The safety of Hyperloop’s passengers is of major importance because of the dangers associated with vacuum exposure. The motivation of this paper is to reduce the probability of being exposed to the vacuum. This paper will look to briefly define the impacts vacuum exposure can have and then moving onto w hat pre - emptive measurements can be taken to reduce these effects, specifically the materials choice for the production of the pods within Hyperloop. This will include looking at the varying materials that can be used to manufacture the Hyperloop pod and w hich provides the most desired material properties. The paper will then look to compare these materials and then choose which is the most suitable as a result of its material properties, including completing simulations using COMSOL Multiphysics to support the research. Within the methodology, the conduction of the COMSOL simulation will be discussed and the different stages of research will again be reviewed. Within the results, the simulations conducted will be presented with the analysis of this compar ed to the information obtained within the literature review. To conclude and provide evidence for the accuracy of the literature review, the materials similarities and differences will be analysed within the discussion through the use of COMSOL simulations 4 There are many factors that contribute to the importance of choosing the correct material for developing the pods. One being avoiding the biological impacts that can occur when being exposed to the vacuum which is discussed in the literature review, an d another being extending the service life and durability of the pods by choosing a material that possesses the desired material properties. This, again, is discussed in the literature review. Safety and efficiency are also something that should be ensured when operating the hyperloop system. These factors combined can ensure a safer hyperloop environment and become more cost - effective. Literature Review Hyperloop technology is being dubbed as the fifth mode of transport, having the potential to impact society and change lives for the better, ranging from social mobility an d socioeconomically to creating new developments in science and engineering. One of the key concerns within this technology is the use of a vacuum system and the potential exposure that could occur. To ensure the chance of being exposed to a vacuum is re duced, crack formation and thus the structural integrity and material choice of the hyperloop pod are vital. The main concern being investigated in this paper is the development of a crack on the structure of the pod as these can have stark consequences. T he strategies used to mitigate this issue are vital in ensuring the safety of all passengers and cargo on board hyperloop with the main strategy being discussed is the use of a compatible materials within the vacuum of hyperloop. Other measures that will b e discussed include the methods of embarking and disembarking, how this is done and how the vacuum would be controlled in this scenario. In the event of crack formation on the pod’s structure, air would rush out of the pod and travel up the pressure grad ient in an attempt to equalise pressure throughout the entirety of the hyperloop system. Causing such force, passengers and cargo would feel it’s effect and be displaced from the pod, ultimately due to the high velocity of around 1000mph for larger cracks [Rob. 2014]. Not only could a passenger face serious injury, but they would also experience a vast range of other biological impacts when exposed to the vacuum. Biological impacts can range from 5 simply feeling lightheaded due to a lack of oxygen to multi o rgan failure and unfortunately death if left untreated for longer than a few minutes. If quickly provided with oxygen or reacclimatised to atmospheric pressure, the passengers would have little to no lasting side effects. In addition to these biological re asons, it is vital to choose the correct material as it needs to be ideal for use with the pressure changes the hyperloop undergo. Besides these biological reasons, the material needs to be cost effective as well as energy efficient. While the main focus o f this paper is to choose a material that proves to be efficient in reducing the chances of crack propagation, these other factors also prove to hold some value and should also be considered. In order to be able to withstand the conditions the hyperloop will be under within the vacuum system, the materials structure of the pod needs to be heavily considered, especially when looking at the extent of the negative impacts that are possible. The Hyperloop pod has many similarities to aircraft, cabins within b oth sets of machinery are pressurised. This is necessary to ensure a breathable environment and to avoid any side effects such as hypoxia. The pod operates in similar conditions to that of an aircraft at cruising altitude of about 33,000 to 42,000 ft above sea level [Pilot Institute, 2021]. At these high cruising altitudes, the ambient pressure compared to the cabin pressure is significantly lower, which is what we see regarding the hyperloop as it acts as a pressure vessel. Thus, materials used for the man ufacture of aircraft/spacecraft can be utilised for the development of the hyperloop pod. As a result, it is wise to use a composite material as it is then possible to obtain the many necessary properties required to ensure there is no crack formation and pressure is kept stable.An example of such material is Carbon Fibre Reinforced Polymers (CFRP) which can be used in the wing of the plane, and it has been used to manufacture a jaguar wing and engine bay door for the use of testing. Not only has CFRP been used in aircraft but also in the blades of a helicopter which has significantly increased its service life [Pao Y W, 2020]. 6 1. Carbon Fibre Reinforced Polymers Carbon Fibre Reinforced Polymers (CFRP) are a likely fit to ensure the desired structural integrity is reached as a result of it being classed as a composite. Composites are a combination of multiple materials allowing for the desired properties of each material to be utilised, thus producing a material that mee ts all requirements. CFRP has a high specific stiffness, strength and fatigue strength of (150 – 300) *10 7 MPA [EduPack, 2023] meaning it is able to endure pressure vessel conditions, with high pressure on the inside of the pod and extremely low pressure o n the outside of the pod [Ozkan. R, et al. 2020]. The high fatigue limit means the structure can take high cyclic loads before cracking leading to a lower likelihood of crack development within the pod structure and not compromising the pods strength. The material also contributes to a weight reduction of more than 20% compared to aluminum and more than 50% when compared to steel [Heine. M., 2021] CFRP also has the potential to undergo a wide range of temperature change with service temperature of the mat erial ranging from - 123 o C to 220 o C [EduPack, 2023]. While the temperatures of the hyperloop will not vary greatly, it is nonetheless an important property because of the need to depressurise and pressurise for embarking and disembarking. This potential sce nario will cause the temperature of the vacuum to increase from freezing temperatures when depressurised to when it reaches atmospheric pressure, which varies greatly. This property is a vital property for hyperloop technology because of change in pressure required to allow passengers and cargo on and off the pods at varying destinations. CFRP is much less prone to fatigue damage compared to that of other materials which proves to be a useful property as it means the development of an initial crack is les s likely. As mentioned earlier, the material has increased the service life of things like helicopter blades. When applying this to the hyperloop pod, an increased service life allows for the pod to run longer without the need for replacement. Composites a re also a lightweight material and this is no different for CFRP, a lighter material will decrease the overall weight of hyperloop technology thus 7 allowing it to travel at much higher speeds. CFRP has a density of around 1.5*10 3 to 1.6*10 3 kg/m 3 which means it also has a light weight [EduPack, 2023]. This property has proved to be highly useful in other industries like the automotive industry. CFRP can reduce the weight of the vehicle by up to 60%, thus increasing fuel efficiency by 30% and reducing CO 2 emissions by 20% [Othman. R, 2019] This composite has a very low coefficient of linear thermal expansion leading to dimensional stability, high fatigue strengths and a high thermal conductivity [Ozkan. D., et al., 2020]. Coefficient of linear thermal ex pansion is the ability for a material to expand under heat. As this value is low for CFRP, the hyperloop pods will have little expansion when exposed to different temperatures which proves advantageous properties for the hyperloop pod. This wide range of advantageous properties makes CFRP desirable in many industries including, as mentioned earlier, aerospace the biomedical field, the automotive industry etc. While CFRP has its advantages, there are several negative aspects related to using the material which must be discussed in order to completely understand its use in the development of the pod of hyperloop technology. The material has low flexibility so manufacturing the product would prove more difficult. CFRP also suffers from brittleness so prior t o the material experiencing a fracture, there is very little to no elastic deformation, it is mostly plastic deformation. However, while this is a disadvantage, it is not as applicable to this scenario as the pod is unlikely to experience a force large eno ugh to cause elastic deformation. CFRP also experiences a lengthy production time and is more costly than the likes of aluminum and steel. Another disadvantage to CFRP is that it has a low thermal expansion coefficient which is vital in ensuring the syste m does not overheat and does become damaged to excessive temperatures. CFRP has a value between 1 – 4 μstrain/ o C [EduPack, 2023]. While these are disadvantages of using CFRP, these are not isolated to the CFRP with many other materials also experiencing these drawbacks. Along with this it should also be noted that the many advantages of the CFRP out way the cons hence why it is a suitable material for the use of manufacturing the pod. 8 Something that should be considered is the impact a vacuum system can have on the material and its properties. CFRP can experience outgassing which is the release of trapped gases when the material is exposed to a vacuum. This not only impacts the quality of the vacuum but also the structural integrity of CFRP. Reducing the quality of the vacuum results in the presence of more particles, more resistance and hence a slower pod and less efficiency as more energy is required. Outgassing can disturb the structural integrity by introducing defects in the material like cracks. The se can lead to the structure being weaker and the chance of the pod reaching failure higher. The material does experience levels out outgassing which is the materials act of releasing gases due to a change in the environment, in this case this change is in the pressure difference as a result of the presence of a vacuum [Pastore R, et al 2020]. The presence can impact the performance of the system as well as providing more resistance for the hyperloop pod. These gases can deposit onto surfaces, causing surfa ce degradation and the corrosion of metal parts. As the outgassing is contaminating the vacuum, it can also cause in an increase in pressure system so in turn reducing the hyperloops efficiency as it creates more resistance. The accumulation of outgasses c an cause a decrease in service life which can be very costly for Hyperloop due it its difficult manufacturing nature. A way to battle the outgassing issue can be to bake CFRP prior to use. Nonetheless, the levels of outgassing experienced through the use o f CFRP is significantly lower compared to the likes of aluminum and steel. Despite these issues, CFRP is still seen as a potential material due to its good fatigue resistance, strength and stiffness. The material can also be pre - treated or even coated to reduce the chances of outgassing occurring. 2. Aluminum Aluminum is another potential material that can be used for manufacturing the pod. It is a lightweight metal that reduces the overall weight of the pod proving to be advantageous as this means les s energy will be required to propel it forward. This is beneficial for energy conservation. The material also possesses the property of having a high strength to weight ratio. When using the material, the low weight would be combined with the property of h aving high strength means aluminum can withstand high stresses while also being quite light. Aluminum has an average strength of around 429.5 MPa [EduPack, 2023]. Thus, using aluminum for manufacturing allows the pod to demonstrate the ability to withst and a high force 9 without the event of crack formation occurring. Aluminium also has desirable ductility making the manufacturing process much easier as engineers can also shape the material into the required shape. However, in certain metals, exposure to a vacuum can cause vacuum embrittlement which is the change of the metals properties due to direct contact with the vacuum. For aluminium, this means it will no longer be a ductile material but in fact a brittle material, leaving it more prone to fracture . This is undesirable. The thermal conductivity of aluminum is very high of around 160W/m o C, especially when compared to the likes of steel [EduPack, 2023]. The same goes for corrosion and oxidation resistance which is important in maintaining the vacuu m seal in Hyperloop. Having a high thermal conductivity can prove to be both an advantage and disadvantage. On one hand, the material can help dissipate heat from the pod and aid maintaining operating temperatures. From the electrical components and machin ery used to run the pod, there can be high levels of heat being generated which can cause overheating. Overheating can be detrimental to the systems of hyperloop for various reasons: it poses a safety hazard, can cause damage to numerous components leading to higher maintenance costs and reduced performance and maybe even failure of the system. Aluminum is able to transfer this heat quickly and efficiently away due to its high thermal expansion coefficient. However, while this is desirable, it can cause is sues as it can lead to unwanted heat loss from the pod resulting in lower efficiency of the system. Whilst outgassing is an issue that Is associated with materials that are used within a vacuum system, this is something of less concern for aluminum as it is a material that has been used within the space industry for many years now. 3. Steel Steel is another material which can be used for the manufacturing of the pod as a result of some of its desirable properties. For many years now, it has been in th e construction industry due to its strong and durable nature. The pods of the hyperloop need to withstand high loads, and thus steels ability to withstand high stress makes it one of the most ideal materials for use in the hyperloop system. Steel is an all oy of iron and carbon and is hence why its properties can greatly vary. Steel has a high tensile and yield strength with the tensile strength ranging from 379MPa to 532MPa [EduPack, 2023]. Having a high tensile and yield strength can 10 be a highly desirable property for reasons already mentioned as it means the chance of failure is less likely. Therefore, having a higher tensile and yield strength means the pod can withstand higher loads coming from the passengers and cargo and so avoiding deformation and fai lure. The ductility of steel is also admirable meaning it can deform easily when coming into contact with a force. This can also contribute to the ease of developing of the pod. This property combined with the high strength of steel means the material ca n avoid failure while also being able to deform and absorb energy without fracturing. This combination is highly desirable. Steel also has a high toughness which means the material can absorb energy without fracturing, which, once again, is important when the material needs to withstand high loads. The material also possesses the properties of good corrosion resistance and thermal conductivity (around 52 W/m o C) [EduPack, 2023]. Due to the large changes in temperature experienced within the hyperloop syste m, good thermal conductivity is highly desirable as the pods ability to conduct heat can significantly impacts its performance. Materials with a good thermal conductivity can dissipate heat more efficiently, helping prevent heat related issues like overhea ting. Good thermal conductivity can also help prevent thermal stresses and thermal gradients. When different parts of a material expand or contract due to a temperature change, thermal stress can occur causing the material to deform or even crack. A signif icant temperature variation along the material is known as thermal gradients which can, again, lead to crack formation, which is undesirable. Thus, a good thermal conductivity is important when choosing the correct material to ensure the chance of crack de velopment is reduced. As steel has a good thermal conductivity, it can reduce the likelihood of cracks and thus makes for good structural integrity. Good thermal conductivity can help facilitate heat transfer, preventing thermal stresses and gradients from forming which hence improves the overall durability and longevity of the material and therefore the pods. Another advantage of having good thermal conductivity is the heat transfer reducing the energy loss which can improve efficiency. A higher thermal co nductivity means heat transfer is more effective thus reducing the energy lost to the environment. This overall improves efficiency of the pods. While steel is seen to be very advantageous for use within the manufacturing of the pod, it does have some un desirable qualities. Steel has a high weight with a 11 density of 7.81e3 kg/m3 which means the overall weight of the hyperloop system will be higher thus reducing the speed it travels at [EduPack, 2023]. Therefore, to go at the speeds desired more energy and a higher cost would be required, making it much less efficient. Steel can also interfere with the magnetic levitation of the hyperloop system. Steel is known as a ferromagnetic material meaning it can be attracted to the magnetic levitation systems of the hyperloop and potentially even magnetise itself. This can reduce efficiency and reliability, cause instability and in a worst - case scenario situation even derailment. This is not something that should be risked especially considering one of the main reason s for choosing the correct material is passenger safety. This ferromagnetic property can make steel a much less desirable property for the use of manufacturing the pod of Hyperloop. Steel is also known to have high outgassing which can heavily impact the p erformance of the hyperloop. 4. Decision Matrix: Based on the research conducted a decision matrix has been created in order to demonstrate which material is the most desirable for the manufacturing of the pod, keeping in mind the reason for this research is to ensure passenger by reducing vacuum exposure through decreasing the chance of crack formation and development. Table 1 – Decision matrix comparing the different material properties of CFRP, Aluminium and steel Properties: CFRP: Aluminium: Steel: Stiffness 5/5 4/5 3/5 Strength 5/5 4/5 2/5 Weight 5/5 4/5 3/5 Strength : Weight 5/5 3/5 3/5 Thermal conductivity 2/5 4/5 3/5 Outgassing 3/5 4/5 2/5 Corrosion Resistance 3/5 4/5 3/5 Cost 2/5 4/5 3/5 Fatigue Resistance 4/5 3/5 2/5 Manufacturing complexity 3/5 4/5 3/5 Magnetic interference 5/5 3/5 1/5 Weight 42/55 41/55 28/55 12 As per the literature review, Carbon fibre reinforced polymers have been shown to be the superior material when compared to aluminium and steel for the development of Hyperloop pods. This can also be seen in the from table 1 which shows the decision matrix . It can be seen with the strength, weight, stiffness and magnetic interference, CFRP performs in the most desirable manner when compared to steel and aluminium. When comparing the potential of the 3 materials, from the literature review steel is the most undesirable material as a result of its high magnetic interference. A property which is particularly important is strength which is the property that will be simulated in COMSOL Multiphysics. The strength of the pods are vital as this is what ensures the s tructural integrity, reducing the probability of crack formation occurring. This is also very important in ensuring the safety of passengers due to the potential issues that can occur when exposed to a vacuum environment. Below, CFRP, Aluminium and steel w ill undergo a simulated strength test in COMSOL to gain more information on whether the composite material is the most desirable choice as suggested by the literature review. 13 M ethodology The key objective of this research project was to investigate the health impacts of a vacuum environment in the context of the Hyperloop pod and explore preventative measures to ensure passenger safet y. The research has considered the following topics: biological effects of vacuum exposure, crack formation and pressure consequences, material structures to prevent cracks, potential materials for construction, and the use of various materials including C arbon Fiber Reinforced Polymers (CFRP) in the pod. 1. Biological Impacts In this initial stage of the study, the aim was to conduct a comprehensive literature review of the biological effects of vacuum exposure on the human body. The vacuum of space presen ts numerous hazards to human health, with the most immediate and significant being the lack of oxygen. This can rapidly lead to hypoxia, a state of oxygen deprivation that can inflict severe damage to the brain, potentially resulting in stroke or death. An other major concern associated with vacuum exposure is the phenomenon of ebullism, which typically occurs at high altitudes, specifically above the Armstrong limit of approximately 19 km or at pressures below 6.3 kPa (Stuff, 2016). Under these conditions, bodily fluids can boil due to the decreased atmospheric pressure. This process causes liquid water to transform into water vapor, which can then infiltrate the bloodstream and soft tissues (Oikofuge, 2016). Consequently, this can result in tissue swelling, bruising, and in severe cases, an embolism caused by gas bubbles in the bloodstream. This not only leads to intense pain but can also inflict internal damage to tissues and organs. Furthermore, the rupture of the lungs is another significant hazard relate d to vacuum exposure, as the sudden expansion of air within the lungs can cause the release of air and fluid into the chest cavity. A notable incident demonstrating the dangers of vacuum exposure occurred in 1965 when an astronaut's spacesuit leaked, when subjected to near - vacuum conditions. He lost consciousness after 14 seconds, and his saliva began to boil on the tongue. In the event of a crack in a pod within a vacuum environment, the lack of oxygen would pose a serious risk, particularly if the pod wer e compromised while the tube remained intact (House et al., n.d.). However, promptly returning the individual to an area with normalized 14 pressure and oxygen levels could improve their chances of survival, contingent upon the duration of their exposure to t he vacuum. 2. Crack Formation The second phase of the study focuses on the consequences of crack formation in the pod and tube with respect to pressure and the material structure required to prevent such occurrences, while also addressing pressure maintena nce. The Hyperloop system, designed to operate at high speeds within a low - pressure environment, is susceptible to cracks and leaks in the pod and tube, potentially compromising the safety and efficiency of the system (Tbaileh, 2021). The dimensions and lo cation of the crack significantly influence the system's airtightness, with larger, centrally - located cracks leading to increased air leakage (Devkota et al., 2017). In response to pressure loss, the Hyperloop system is engineered to activate emergency bra kes and safety measures automatically, safeguarding passengers and mitigating accidents (Musk, 2013). Crack formation leads to the development of a highly under - expanded jet, culminating in a distinct Mach disk. As the crack width expands, a more extensive oblique shock cell structure forms (Kim et al., 2022). The leading shock wave generated ahead of the Mach disk propagates as a normal shock wave, with its propagation speed and pressure rising proportionally to the crack width. Preventing crack formation necessitates a carefully designed vacuum tube structure, which can be constructed overhead on pylons, at ground level, or below ground, depending on the terrain conditions and curvature requirements. The pier spacing that supports the tubes is critical for achieving the design objective of the overall structure, with an optimal span length typically ranging between 20 m and 40 m (Braun, Sousa and Pekardan, 2017). The alignment and curve radius must also be considered during the design process to ensure pass enger comfort and safety. To detect cracks and other material defects, non - destructive testing techniques such as X - ray and ultrasonic testing can be employed to verify structural integrity (www.hse.gov.uk, n.d.). 3. Material Structure and CFRP The proper s election of materials is crucial for ensuring safe and efficient operation of the Hyperloop system. Different types of materials can be utilized, such as Carbon Fibre Reinforced Polymers (CFRP), Aluminium, and Steel. While steel is commonly used due to its favourable weight to strength ratio, high stiffness, and 15 yield and tensile strength, it can be costly and susceptible to corrosion. To address these issues, SAE AIST 1018 steel is frequently employed in the Hyperloop system as it possesses high strength, weldability, surface hardening qualities, favourable mechanical properties, and machinability. The cold drawing process improves its tensile and yield strength, surface hardness, and wear resistance, though it may lower its ductility. Steel reinforced conc rete has good compressive strength and cost - effectiveness, but its low tensile strength and porosity levels can be disadvantageous. It is vital to use materials with low outgassing rates, high bake out temperature tolerance, and low absorption of water and gases to maintain a high - quality vacuum (Civiltoday.com, 2019). Several materials, including cadmium, zinc, magnesium, lead, and certain plastics, should be avoided due to their outgassing and residue issues. Austenitic stainless steel, alloys with excell ent weldability, aluminium and its alloys, nickel, brass, and platinum are commonly utilized in vacuum environments (Weissler and Carlson, 1980). For windows, borosilicate glass can be machined and joined well with other materials. An investigation by Lope z - Puente demonstrated the impact of low temperatures, specifically 25 to 50 Celsius, on the failure strength of CFRP, indicating that it increases proportionally with strain rate. Furthermore, the study revealed that temperature does affect the mechanical properties of CFRP, particularly in terms of intermediate and high velocity impact responses (Ou et al., 2016). Maintaining constant pressure within a Hyperloop pod necessitates a comprehensive sealing system. Drawing inspiration from spacecraft design, a two - door airlock system can be employed for ingress and egress of astronauts, thereby ensuring pressure stability at approximately 14.7 psi (101.3 kPa) at sea level. Furthermore, a dual - O - ring configuration, akin to those utilized in large vacuum chambers capable of sealing vacuums as low as 10^ - 8 Torr, can offer a dependable seal. With a clamping force exerted on the O - rings at around 800 pounds per linear inch, the external O - ring maintains a rudimentary vacuum, while the internal O - ring confronts a redu ced pressure differential (llis.nasa.gov, n.d.). Porosity, induced by hydrogen, can undermine weld strength and compromise a spacecraft's ability to sustain constant pressure. To mitigate porosity, various process control measures are adopted, encompassing the cleansing of metal surfaces and filler wire, verification of chemical composition, assurance of shielding gas purity, and regulation of metal component alignment. Although non - destructive testing techniques might not wholly detect porosity, pinpointin g and eliminating contributing factors, coupled with analysing stress concentration surrounding cavities, facilitates a better comprehension of the correlation between pore size 16 and strength reduction. This insight contributes to refining the welding proce ss, ultimately guaranteeing the spacecraft's ability to maintain constant pressure during its operation (National Aeronautics and Space Administration, 1972). Results Simulation In order to determine the most suitable material that would ensure the least possible chance for crack formation, simulations using COMSOL Multiphysics were c onducted. Each material was tested in regards to its structural analysis and how it would perform in a vacuum to determine which material is the most desirable and whether CFRP, as shown through the literature review, is the best choice of material. One of the most important properties used to decide which material is the most suitable is its tensile strength. Therefore, each material underwent a tensile strength test. In Figure 1, a model developed in COMSOL can be seen. I n Figure 1 the Hyperloop pod can be seen to have a generalised shape within a cylindrical shape. This cylindrical shape is acting as the vacuum the pod would be within. Within this simulation, the pod itself will be si mulated as steel, aluminium and CFRP, as already discussed. 17 Figure 1a – View of the Pod within a vacuum system Figure 1b – View of the pod side on within the vacuum system. 1. Steel 18 Below are the results obtained for Steel Figure 2 – Simulation Results for Steel From the colour scale, Figure 2 indicates that t he average tensile strength of steel is about 1.5E5 Nm 2 19 1. Carbon Fibre Reinforced Polymers (CFRP) Below are the results obtained for CFRP Figure 3 – Simulation results for CFRP From Figure 3, the colour scale indicates the tensile strength to be around 0. 9 E6 Nm 2