Hi, welcome to this channel. This RU-vid channel is dedicated to the education of students in engineering and science. The topics covered will relate to various aspects of engineering materials, mechanical design principles and some specific topics on tribology. Tribology is more of my research interest. Tribology is defined as the science and technology of interacting solids. It is the study of friction, wear, lubrication and related topics. These are the kind of issues we have to deal with in bearings, joints, tyre, metal processing, etc. I will constantly add new videos. If you have any comment or question related to any of the videos, please write them in the comment section and I will get back to you as soon as possible. In order to popularize this channel, I also request you to like the videos you have watched and also subscribe to this channel. Thanks you very much in advance. Sujeet Kumar Sinha, Department of Mechanical Engineering, Indian Institute of Technology Delhi, India.
So the fibreglass didn't break at all, just the epoxy broke? Which explains why you got about 200 MPA rather than 3400MPA which is the tensile stress of the fibre.
Respected Sir, Which book can we read the correct explanation of all the lubrication regimes with real world examples that also give detailed explanation about the curve? Kindly tell
How equal will the elastic moduli be obtained using the direct tension or compression method and ultrasonic bulk wave through transmission measurements?
Respected Sir, if possible please make a video explaining how different load acts on different types of bearings through Free Body Diagrams. Although it is written in different books that bearings take up radial, axial or combined radial and axial loads but understanding by mere reading the book becomes difficult specially how to visualise the loads acting on the bearings and why a particular type of bearing is suitable for a particular load category 🙏🙏
Hello sir, i am using an additive to my mineral 15w40 engine oil and this additive contains the long chain chlorinated olefin. I am using this additive since the end of the 90's without any problems. Is it true that the Chlorinated Olefin WILL corrode the engine regardless of the additive mix? The additive is resitant from -50 to 315 degrees celcius. Thank you. Rob
Rob, General belief is that the presence of chlorine will corrode metals and it is true. However, I do not have data for your type of application. It is interesting for me to know more about the additive molecule you are using. Could you share? Thank you.
Good question. For any polymeric material, increasing temperature means reduction in tensile strength. This will happen very drastically. Even within a day or during seasonal changes from winter to summer, you can observe this change. For glass fibre reinforced composite, the same will happen but some what delayed effect. That means GFRP will be able to retain its strength at a higher temperature than the pure plastic. You will need to generate data if you want to know quantitative answer. Please do check in books or research papers.
Plastics Engineering by R J Crawford Mechanical Properties of Solid Polymers by I M Ward and J Sweeney. drive.google.com/file/d/11LTR8GDOGwYCE7fWBEV-vck6uKlRbmBd/view?usp=sharing
If the yoghurt is easily flowable then the rheometer described in this video can be used. For yoghurt that does not flow like a fluid then perhaps you should conduct compression test, just like we do for cheese.
I think it would have been more durable if you had also applied the vacuum process. The vacuum process both eliminates air bubbles and allows the epoxy to penetrate into the bamboo.(Of course, I have no idea how much bamboo absorbs epoxy, for lamination with epoxy, especially resin-free tree species are selected and treated with epoxy.)
You are right, vacuum could be tried. Our specimen was quite large which prevented us from using vacuum. I also do not know if vacuum can help absorb more epoxy inside the bamboo fibres.
Hi Prof., can you provide some insight on how friction reduces when speed increases from mixed to EHL? Also, share thoughts on the film formation mechanism in the EHL region. Can EHL be applicable to flat-on-flat contacts?
Thanks for asking. As relative speed increases, greater amount of fluid is pulled between the two surfaces because of the stick wall boundary condition between the fluid and the surfaces. More liquid coming in causes a hydrodynamic pressure at the interface and hence greater load bearing capacity is created. This causes the surfaces to move apart with thicker fluid film. Hence, the coefficient of friction decreases because there is no solid to solid contact anymore. In EHL, the above action happens but one more thing happens which is that the contacting surfaces deform elastically providing even thicker liquid film formation. For example, this is also the cause of hydroplaning when you drive at high speed through a pool of water when it is raining. The tyres deform and provide more water coming in between the tyre and the road surface. This effect is large when the tyres of the vehicle are little worn-out or smooth.
Thanks so much. Hardness has been defined as resistance to plastic deformation. That's somehow similar to stiffness which is resistance to elastic deformation. My question is: is hardness analogous to stiffness, is it a rough equivalence of stiffness in the plastic region? I'm asking this in the hope that there's a way for me to make sense of hardness using the stress strain curve even though tensile test doesn't measure hardness. I keep wondering about that given that stiffness and hardness have the same unit and similar definitions. Would love to get your thoughts. Thanks
Hello, Thank you for the detailed video. Could you also explain how storage modulus is related to Young's modulus, if any? I have seen people using these alternatively. But these are two different properties. Isnt it?
Briefly storage modulus is actually the elastic modulus part and hence we can say Young's modulus. The word storage is used because it means the elastic energy is stored and can be recovered upon release of stress. The loss modulus is the part of energy that is lost due to viscous flow within the material. It is called loss modulus because that part of energy is lost in heat and other dissipative work.
Thank you for your response. But if I want to consider the JKR adhesive force between two spherical cylinders, would this formula still be applicable? Or what modifications should I make?@@engineeringmaterials-tribo5142
Thank you so much for this video, really helpful. I was wondering what formula for the friction coefficient can we use. in case i want to compare an experimental results curve with another theoretical curve?
The final stress a specimen can withstand before fracture initiates. In a tensile stress-strain curve it should be the highest point on the stress axis.
Very informative. For viscosity values shown in the table, should we exclude the measurement at point 1 as it gives a totally different value from points 2 to 20?
time 23:55. Yes you have pointed out an important aspect of the data collection. Often the initial couple data may be totally different and need to be omitted. Also, every test must be repeated at the same set of conditions three times, at least.
