High-Level Project Summary
Magnetic lock is a devise, that consists of 1 permanent magnet, 1 solenoid and 1 ferromagnetic. The cable is placed between the magnet and ferromagnetic. As was required by the challenge, our device is fully resettable, does not use pyrotechnics and opens like a lock without bringing any shock. It has two states: locked and opened. In the first one, there is no current in the solenoid, and magnet interacts with the ferromagnetic, producing force that keeps cable fixed. In the second state electromagnet starts opposite to the magnets magnetic field to reduce its influence on the ferromagnetic. After that attraction of ferromagnetic becomes smaller, so cable is free to go.
Link to Project "Demo"
Link to Final Project
Detailed Project Description
Magnetic lock consists of three main elements: one permanent magnet (made of nickel-iron 50/50), one solenoid (made of copper wire and stainless-steel core) one ferromagnetic (made of permalloy), and titanium alloy. The main idea of this device is to keep cable fixed or free with help of magnetic interactions.
There are two states of our device: locked and opened.
Locked state
There is no current in the solenoid, so it is no magnetic field produced from is.
Permanent magnet make an external field (B ≈ 1,5 T), which influence ferromagnetic, so it starts to produce its own magnetic field, which is explained by the phenomenon of magnetic hysteresis. As a result, magnetic field intensifies (B ≈ 1,68 T) and magnet attracts the ferromagnetic with the force
F ≈ 1,7 kN. As a result of magnetic and friction forces, cable which is clamped between the magnet and ferromagnetic remains fixed. Titanium alloy keeps the rib fixed and can work with loads up to 3,4 kN theoretically. If to scale this mechanism, it can work with much more higher loads.
Open state
Current starts to go through the solenoid, creating the magnetic field with the B ≈ 1,8 T but with opposite direction to the magnetic field of the permanent magnet, so the resulting field B ≈ 0,3 T. It would be perfect, if magnetic field of solenoid would fully compensate the magnetic field of the permanent magnet. Now it is weaker external field applied to the ferromagnetic (B ≈ 0,34 T) so the force also becomes weaker F ≈ 69 N. Titanium wall will move away and release the payload. So now cable is free to go.
Space Agency Data
In this project our team used information from NASA, Soviet and Russian space programs and ESA and open source data from Space Apps. This information helped us to understand which technologies are used nowadays and were used in past days, informed us about specific conditions of different spacecrafts and space objects were those spacecrafts must land smoothly. We read and watched s lot of of texts and videos from Space agencies mentioned below.
Hackathon Journey
Honestly, these two days were tough for us, because our team consists only of two students, and we had plenty to do. First problem was that we tried to create something conceptually new, something that we didn’t see before. This is challenging, because engineers are smart people, and if something is well done, it will be used, and if something is not good or not efficient enough you wouldn’t hear about it. Nevertheless, we decided to play with magnets and to use magnetic interactions instead of pyro-magnetics.
We started with the simple brainstorm and first our idea was to put the cable between the two magnets and than repolarise them, so instead of attracting to each other, they would push from each other. But permanent magnets are hard to repolarise, and it is harder to make friction with the electromagnet. Then we developed concept when two fixators are clamping the cable between them, and they are fixed with the ring which is made from the ferromagnetic material, so when the electromagnet in the bottom of the construction will be turned on, the ring would be attracted to the solenoid and fixators would fall one from another, so the cable would be free to go. We almost started to do the calculations, when we realised that we couldn’t be sure that friction between fixators and the ring would be strong enough to keep it in its position. So, we decided to change the concept a bit and that is how we came up with our final idea. When the concept was approved, time of modeling and stress analytics. To provide strength and generate the final model. I calculated that with mentioned magnets we can provide safety of mechanism up to 3400 N. But Ansys analytics
shown that in some cases it can withstand 4000 N. Modeling took the biggest part of time, because we needed to rebuild model 3 times to make it working and correct.
I (Anastasiia) was occupied with calculations which are related to the magnetic fields. It was the hard part for me, because it is a large topic, so you need to fall deep into it to make everything correct and precise. Two days is not enough time for covering this topic, so it feels like I have missed something or have done a mistake in calculations. But, otherwise, I had fun reading all these articles about magnetism and applying them to our project. I think that even our device isn’t so practical as devices that based on mechanics, it is still an interesting idea to develop. I appreciate that time I spent on this project. That was a whole new experience for me and I’m thankful for it.
And I (Maxim) done models, drawings and stress analytics. I used my laptop a lot to work on this project for two days. Reading articles, watching videos, scrolling for mechanical characteristics of different materials to ensure the quality of our decision. I had a good weekend doing things I like a lot, brainstorming and calculating.
References
- Smithells Metals Reference Book (Eighth Edition)
- Magnetic Materials and Their Characteristics
- http://info.ee.surrey.ac.uk/Workshop/advice/coils/force.html
- https://en.wikipedia.org/wiki/Force_between_magnets
- Einfuhrung in den ¨ Magnetismus gehalten von Prof. Dr. Gunther Bayreuther ¨ Universit¨at Regensburg
- И.Е.Иродов ОСНОВНЫЕ ЗАКОНЫ ЭЛЕКТРОМАГНЕТИЗМА
- https://ru.wikipedia.org/wiki/%D0%9C%D0%B0%D0%B3%D0%BD%D0%B8%D1%82%D0%BD%D0%B0%D1%8F_%D0%BF%D1%80%D0%BE%D0%BD%D0%B8%D1%86%D0%B0%D0%B5%D0%BC%D0%BE%D1%81%D1%82%D1%8C
- https://www.engineeringtoolbox.com/permeability-d_1923.html
- Appendix B: Material Properties
- https://inzhener-info.ru/razdely/konstruirovanie/metalloemkost-konstruktsij/legkie-splavy.html
- https://almet.ru/directory/plotnost-alyuminievyh-splavov.html
- https://aluminium-guide.com/plotnost-alyuminiya-i-alyuminievyx-splavov/
- http://www.splav-kharkov.com/mat_start.php?name_id=1386
- https://metallicheckiy-portal.ru/marki_metallov/tit
- Strength of Materials Pisarenko
- Methodical instructions to calculation and design tasks
Tags
#landingsystem #parachute #withoutabang
Global Judging
This project has been submitted for consideration during the Judging process.