RESONANCE - HOW TO DETECT - HOW TO SOLVE

hello and welcome back to another episode of the reliability game podcast and you'll see us now in our brand new workwear well I love this work where do you it's really good I'm really glad we managed to we've we've Consolidated everything we've got a standard together and it's just it's really nice I just it's very I know I think I said see deny image is everything so if you guys can watch and Via YouTube right now you'll see us um again we've been away for a while we've had a lot of changes in our business um I'd say for the better in terms of where we're going but you know sometimes it the thing is about running a business it's a roller coaster it generally just you just don't know like from one day to the other your whole business Outlook can change and you know we've we're doing great I'm not it's nothing bad but it's just we've had a few Personnel changes and a few pivots and stuff like that so again we've had to kind of really kind of jump back in and I did say on the last podcast that I wanted to do this every two weeks I'm not even going to say how often they're going to come now so when they come they come yeah um but it's just yeah it's just we've had we've had a lot to kind of to deal with but we just said we want to come back and talk about some some resonance didn't we we want to talk about some vibration things again you know get back to the roots get back to where we're coming from and I think like talking on your point I'm reading this book at the moment that I think you'll really like and it just you realize that in life and in business you're really not in control of a lot and like no matter how good we're doing or what we intend to do something comes in that we can't control and just that's the thing I think you know being a business owner and having sanity right or you know having having the ability to be able to just live your life without that constant what's around the corners just to accept the fact that we don't have control of what happens and we don't really know what's going to happen next but you know what as long as we're in the present moment right now and doing all you can to help your customers and and grow your business and and be able to give as much value as possible and as much Insight then that's all you can actually do you know what I mean and I think since I've started to have that outlook on life my anxiety and my mental health has improved massively because it's really difficult especially when you're looking after you know a team of people you know and you're responsible essentially for everyone's kind of well-being to a degree in terms of what you're doing it can it can get on top of you but I think sometimes it's just to let go a little bit and just to be able to say do you know what as long as I'm doing everything I can right now then the rest will be able to take care of itself as the universe says so resonance yeah yeah we've had so many like what we'll do we'll talk generally on it but we've had quite a few experiences that we'll talk with as well I mean we can't name any customer names um for NDA reasons but there's a few applications that I think oh we've had some really really interesting cases and some really easy fixes to yeah problems that and hard fixes too some really complex issues I suppose as well it's probably worth mentioning obviously we're going to have people listening that may have an understand of resonance but if you're an engineering manager or you've got a plant what sort of equipment will can they expect to see these problems with well in terms of looking at say average a plant you can you can get problems with pipe work you can get problems with mowers fans being a big one you know generally quite a lot of Mass on a fan that that will rotate in natural frequencies with fans can be in critical speeds is very common because fans in a process environment will run at different speeds or ramp up around now due to processes we which can interfere with critical speeds gearboxes as well yeah a lot of people that we don't see yeah we had a lot of we were the issue with a very big gearbox actually so you know gear Gear resonance is is a big one as well and then when that happens it can get really scary you know you you see I think the particular case that we'll go over um you know that me and will were working on about two years ago was the highest reading I've ever seen yeah it was kind of like yeah it was literally like no this is definitely like clear-cut Spectrum nice definite Peak but it was just a scale in that kind of like yeah it made me feel a little bit sick when I was on when I was on the vessel as well the reader made me feel sick the actual The Vessel didn't but um yeah it you know when you see these things I think with resonance as well the identification is quite easy to know because you'll you'll you'll just feel like oh my God this is a little bit it's crazy we should probably like try and Define for anyone listening what resonance is yeah of course do you want to do that yes Will's just that is level three anyway so yeah anyway just quick not getting off the point or anything but we'll just complete this level three I took him through it and he's just he's loving life now in the vibration world how much Insight it teaches and how that gets you to the next level of your learning is is just incredible and when I did it but he's obviously embraced that now and he's now on this level three Journey as well as engine so congratulations on that will thank you yes for anyone listening resonance so I'll try and explain this as simply as possible but uh in the world that we live on we've got structures and fans and bits of machinery and these bits of equipment have a natural frequency uh within them is that kind of happening yeah oh I would say every every single object or even people have natural frequencies uh and it's just the makeup of that matter and how it vibrates have a vibrates at a certain frequency a bit like um I'm gonna a bit like a guitar string or a piano note you know there's set frequencies if I remember my music theory like a on a piano I think it's 440 Hertz that they tune the piano to don't quote me on it I don't want to get in any trouble no that's not right but um that is the natural frequency of that string and it vibrates at that frequency now what a resonance is is if we take that natural frequency of whether it's that string or whether it's a fan structure and we excite it by something else potentially the machine running at a similar frequency external force or an external Force then that vibration that that will amplify itself it will so you get two different responses and what happens is them two responses then start to come into phase with each other so you get the response frequency that's not more existent until you excite it that makes sense now when you excite that frequency then it starts to exist that with the net with the forcing frequency right the two waveforms add together and what happens when you add two waveforms together amplifiers gets bigger and when you get to a certain point with that critical speed when they match you then excite the resonant frequency of that structure or object so you've got the response frequency and then you've got the frequency imposing on it which is a force and frequency it could be a speed it could be the motor running speed it could be external forces or it could be something externally so if I if I actually externally vibrate the guitar string or strike it that's the external response then the natural frequency then takes holding the two frequencies add together that create that resonance what creates the guitar string to vibrate viciously that then gives the sound so um yeah the two frequencies added together will create these phenomenons called resonance and you know you've seen probably a lot of images like the Tacoma Bridge one was a great one from the Mobius Institute when we when we're teaching the resonance and you just see the bridge like literally twisting and flexing in your second mode of resonance as well YouTube the Tacoma Bridge there's a lot lots of content that you guys can go and have a look at definitely yeah and then one of the methods that we do use to be able to detect resonance is Bump testing and we can use um run up close Downs as well and usually what you'll find when you are going for a resonance is 180 degrees shift between the force and frequency and the response frequency so when you start to get interphase into the middle part that's why you get a higher vibration and this is when you start moving away from the critical speed for example with a fan it starts to vibrate less because the phase is actually then not in Phase it's starting to move out of phase with the response frequency and as you move our phase the response frequency really dampens okay and I suppose for anyone listening like this vibration when it starts going into resonance can be extremely catastrophic aren't it oh yeah it can destroy machines so when you do get this circumstance or the scenario and what usually happens is something changes with the machine so usually some form of Maintenance has happened on the machine someone has tightened a bolt or something like that or someone's actually out with the structure of the machine because how we actually alter the natural frequency of an object or machine is either to be able to add more stiffness to that structure or add to add Mass yeah and I think a great like analogy to look at that is as you move up on a guitar the strings get thicker there's more mass on them so the frequent the note has changed the frequency changed and then equally so if you want to change that strings natural frequency as well you would also tighten up which is stiffness so that that's um what we got so as we actually um increase the stiffness of the machine right the natural frequency moves up okay as we add Mass to a machine it actually moves down so you've got this phenomenon of adding mass and stiffness and then you've got something else called damping so damping doesn't actually change the natural frequency of where it sits on the frequency scale it just it just soothes what they call Q factor which is the resonance factor of how much it will vibrate when them two frequencies get into response with each other so it will just dampen the actual frequency because some scenarios is really difficult to be able to change a natural frequency depending on what we're looking at there's some really cool um stuff we did in cat 3 on mass dampers in buildings oh my gosh yeah I mean you see these huge dampers in some of these Taipei 101 is a big one I think it's got a big one big old shot yeah and then in the top of these builds these huge masses that are suspended on these kind of Springs and it's just like the engineering that's involved imagine like you know designing that yeah I want to be responsible for that that's crazy a video the other day and it was a big tower that was built in Central Park New York and it's a big residential it was like a 250 million pound apartment and at the top though they went up and they showed this Mass damper I kind of got a bit excited and just my wife yeah we were never my little friend so uh but yeah no really interesting but in terms of residence rule you mentioned the fact obviously usually it's a mechanical change like a maintenance-induced things but what other things can cause resonance ah well I think anything that is there's potential to change the mass of that structure or change the stiffness because you have to you have to think why does residence actually come into play after it's been okay is because the force and frequency of a mo or whatever's running is not matching the natural response frequency right and there has to be a change within that response frequency for it to be matched or come into play or the process has changed so that means the force and frequency that is imposed onto the machine would have changed because of a process that's not usually there and that's quite rare to be honest because generally machines will have a set process of how they run with a function and that the process generally wouldn't change but what you can get is external forces like pump cavitation or things like that that potentially could come into play yeah that weren't there before that can then change the force and frequency so you have to think of it as the force and frequency and the natural frequency is there anything that can change the force and frequency so it didn't match as the natural or is anything that can change from the natural frequency the stiffness or the mass of that structure then can can meet the force and frequency change so when we're looking at especially fans I mean this is critically important for fans as well because fans a lot of fans especially in the mole industry I mean we've got a lot of malt customers and we've seen a lot of resonance issues with this as well where what would you'll have through the kilnin process is different stages of of different heat or airflow that requires the the kilning process to be able to create a product so what what they'll do is restrict the airflow which they'll restrict the speed of the fan in certain stages of where the fan goes so a fan could potentially be running from 30 all the way up to 100 depending on on what part of the kilnum process they're in um all the kilner's gonna get at me now and say no that's not right it's just an example so if we are you know just just basis on examples so say for example and every single fan as well has critical speed so I suppose you know you use The Malt industry as an example and we've seen this quite a bit you've got this process requires the fan to run at various different speeds obviously design is quite important then when it comes to fans it's hugely important and we've even dealt with a lot of scenarios the reason I brought it out we've got to be a little you know end over there we're not going to name any names but this is purely in the basis of just being to educate people in terms of understanding why the design and for anyone that looks after maintenance or is in the in the works of projects and stuff like that is something that should definitely be in the back of your mind if you're putting in a new fan or you're involved with the project with installing a new plant that you know might have a bit of equipment understanding the fact that resonance is something that must be considered in that process oh hugely and again I think a lot of the time where you're looking at these type of processes especially when you look at ahu's as well because Asus will again depending on what airflow is likewise not very stiff structures and are they inherently so they're no they're not and again when it comes down to that it's understanding where the natural frequencies are so you know finite element analysis is another technique that is used in terms of software programs like the design stage the design point of view to understand exactly what the natural frequencies could be and kind of trying to simulate um the force and frequencies as well I think that's quite important to mention is that we can't eradicate uh like it's natural is natural this is this is laws of nature this is what I love about engineering it's about you know the laws of nature will never be changed right we have to abide by these laws same as laws of electricity we could harness electricity right and we can safely use it look what we've done this civilization with electricity in terms of from the from the initial Dark Ages to where we are now and yeah even understanding the existed look how we've harnessed this this beautiful natural kind of you know element to life and how we've harnessed it into even this podcast right now and how we're recording on computers and how we've harnessed is amazing but it's the same with the natural laws of resonance right we don't want to mess with this so we have to be really aware of it does exist and we can't change it we have to work around it we have to harness it so the idea is of using these tests and you know taking this seriously as well because because sometimes if we don't the actual implications can be so catastrophic I mean we've we've seen like fan failures completely eradicate machines in terms of the destruction it can cause quite scary like when we look special like we were like is this real what we're seeing is and you know we could even when we was on the vessel we could feel it it was that you could hear it it was it was a horrible pitch it was a horrible tone and when you compared that to the other engines on the vessel you knew there was a problem you knew that something was up and when you've got you know Machinery that's big and it's traveling at extremely high speeds right you know it's a health and safety problem as well you know it's a health and safety issue in terms of what we're doing because when we're on these plans you've got these fans rotating potentially at 3000 RPM huge masses that are rotating at such high speeds like you know the implication of if you do meet a resonance scenario that fan will fail very quickly and it won't be able to be detected quick enough to be able to be rectified if there is a a sudden change in yeah in in that structure or a sudden change in that frequency so the design says as we was talking is so important to make sure that we design out any of these problems before they become issues that that's before even we can detect it if that makes yeah because like we did this in uh ARP like when it comes down to the design stage you know doing these checks doing these things like FMEA you know they are going to cost more than if you weren't to do them but as you move out of the design stage and into the information and commissioning when you start finding these problems the actual cost to rectify them out of design stuff it becomes even more but that's the thing isn't it like again I was having a good discussion at one of my biogas sites from the plant managers there yesterday and we're kind of on a mission in a minute to really try to change the coach of the whole company I mean he he loves what we do and he's kind of trying to get us on all the sides but it was almost trying to have this discussion at one of the sites that they've literally just built they're literally it's just Brands is this the one local to where I am very local to where you are and you know the conversations about the fact that they're not even going to grid yet because of initial installation issues and problems that you know what I mean if we're rectified there would be literally running now you know what I mean design and installation is you know definitely another topic for another podcast but it's oh God compliance testing as well we can go over that acceptance testing as well and this is where we can really help because a lot of companies will accept things on the basis oh it's brand new without the the tests done on them and then if we can identify these problems well before they're there it's just saves so many problems down the long run because essentially as well if you have an acceptance testing kind of procedure it allows you to be able to cover yourself when something isn't designed right now I'm telling you guys things you know it's quite common that yeah things are not designed correctly I mean the one that we had uh with the Asus you know this was we were talking about resonance problems and Laser alignment and belt alignment and we were talking with these issues directly with the fan manufacturer who didn't do FMEA who didn't understand resonance who didn't do laser Alliance they didn't even vibration test these assets when they left the factory and this is this is where I don't know I don't know where diligence with your supplier I think so but I think I I'm a little bit shocked sometimes so I think I was usually on the assumption that these things were done yes I I was you know and then when I found out that these things are not even being considered I'm like what what at them at the manufacturing stage as well yeah so I think there's a level of awareness then it's not pointing the finger at anyone it's just trying to say well how do we make industry more reliable and that way does at the end of the day it all starts a design yeah right if design can be done correctly then we don't have to intervene and do a lot of these things along the way we don't even need to conduct a root cause analysis of why because it was all in the design I think when we look at like lots you know good 70 of the problems we come across on a daily basis it falls back to oh that was poorly designed or that was actually installed wrong yeah or they didn't think about how they're going to mount this thing and you know even even you look at majority of motives that are mounted in the plant right and you see how flimsy they are and how flexible they are do you know what I mean this is another cause for for a lot of resonance issues as well because you know even the fact that tightening four four bolts down can't be done correctly is a huge problem and I think like I don't think we're going to change design and installation anytime soon that's a long game though hopefully this does is anyone listening who manages projects or manages a plant maintenance or anything like that has the thought processes of I need to ask these questions when I'm getting something new installed or have we considered resonance or how will you mitigate in that with your suppliers have what experiences have you got in the plan because I guarantee that there's somewhere every single plant we go to it's like oh God when this particular piece of pipe work is always shaking or vibrating this way and the fact is that a lot of these things don't get rectified until they fail do you know what I mean and it's like you know quite clearly there's issues with these particular problems or resonances on site or if you have an asset that is you know vibrating a hell of a lot more then all the other identical assets there's some resonance problems somewhere within that particular plant and the nice thing with resonance without getting too technical it happens at usually lower frequencies yeah and so if you have got assets you you're going to feel the vibration you're going to fit like if you're sit if you're in a building you can feel the floor in your office shaky something's probably resonate out there exactly so I think it's about a identifying if there is resonance and if you know to be able to do that you need to have some form of condition model vibration testing anyway to identify there is a problem or you know generally you'll know about it if it's a bad resonance or you might not because if you've got hundreds of assets on site you're not able to be able to check every single asset you haven't got through team PPM inspections where someone checks these things you may have these issues of problems happening you know without you even really knowing and when that is the case then these things will fail before you know about them as well so having a good routine you know condition based maintenance you know practice is key and then when you do find issues or problems it's not assuming that them issues and problems are imbalance or looseness it's then doing the actual checks that allow us to be able to identify a resonance issue and problem without having to then Rectify all of these things then to realize oh it's a resonance problem so the idea is you know when we go anywhere and we do see excessive vibration there's certain key indicators to look out for to understand there is a resonance issue as well so the things that we do really want to look out for is really high vibration and one axis okay so resonance is very directional usually you won't see high vibration or free planes when you're seeing a form of resonance you'll see extremely high resonance in One Direction yeah and and fairly low in the others that's a real good indicate of potential resonance issue obviously High one times is where you'll find the resonance because usually what the critical speed is running speed related yeah it's usually the running speed that is is is then obviously coinciding with that response frequency so that can be also a really good test as well like if you are suspecting a resonance you don't have lots of complex vibration analysis equipment what you can do is usually it's to do with the One X and so or the run running speed of the machine so because resonance is directly related to that if you turn the machine off that vibration should dissipate very quickly very fast yeah compared to say an imbalance where the mass is always there there's always an imbalance as it runs down the vibration is slowly remember with imbalance speed is proportional to vibration so it's linear so if you've got a slight imbalance even at lower speeds you should feel that one times going around be a slow array but you'll see that vibration usually what you'll find with with a resonance scenario is it will be the machine will be fine up to like 70 it'll be running sweet as a nut then as soon as you get to a certain frequency which is obviously the response frequency resonating it will start shaking crazy and you know whoa and you'll notice that as well through all fans that are ramp up because every fan will have a critical natural speed and you know you'll you'll be going through different modes of resonance as well as it ramps up to its speed yeah there's different modes of resonance as well that's kind of getting a bit more technical but when we're looking at you know critical speeds you'll get through a first critical you get for a second critical and generally you'll then start to get to your running point of your machine depending on how fast that fan is moving whether that is an idea is at the design stage the fan manufacturers should be understanding where you want to run should be running at and then understand where they should stiffen the structure to ensure that the first encyclical critical speeds are knowing near it well 20 away from any critical speed is is the standard so to speak as well so again again if that hasn't been done and there's a random element of oh I don't really know then you're quite likely to be potentially running at a resonance speed which is then going to cause your machine to to vibrate and fail a lot quicker than than it should do and that's all the part of reliability again as well isn't it it's it's understanding that it exists and trying to make sure that your machines run as smooth as possible do you know what I mean and I think this is the thing as well even trying to get to trim balancing and and get your get your fans operating as low as possible like this is this is something I didn't really consider when I first died and it was a bit like oh well it's not vibrating too badly but it's the idea of okay well I'll be actually improving reliability here are we not and it all depends on the ethos on site because sometimes you know it's great to have that reliability mindset but if you're at a site that has yeah a million problems do they really want to trim balance a fan down to five millimeters per second to one for example that's least of their concern so it's got to be proportional to the problems that you have on site but again if we are reliability Engineers we've always got to have that view to improve Machinery so it's always really just talking it's just taking steps at a time rather than trying to do everything at once I mean that's that's I think when we first started we probably tried to take customers too much on a critical hyperspace mountain right from North to 100 you know very quickly it's because we love what we do and we're passionate and we see see the angle but now I think we've we've we've learned massively that you have to approach it so differently depending on who you're dealing with because you know a lot of the guys I think as well Engineers of course they want a reliable plant but it's just it's just they've got other concerns and priorities at that point and how can we help them with them priorities I suppose to round it all off I guess resonance though is a high priority it's huge it's massive so whenever you do have a residence it's like it has to be solved straight away so when we're looking for residents so I got off point there a little bit like please bear with us because we do go on tangent go so when when looking for resonance as well we're looking for a really high vibration in One Direction yeah usual fine resonance is very directional okay as well what we are looking for is Extreme increases of vibration over small areas of speed increases so you're looking at that huge ramp up over small periods of time you're looking for machines is that that seem to be fine at certain processes than other processes you're getting really high vibration really high vibration responses as well so yeah anything else add on that will in terms of what we're trying to find I think that covers the most common things that we look for obviously there's other more complex resonances but I think for anyone that's got a bit of a oh we've got that machine that gives us a few problems those are the points to go look for to see if it potentially might be a resonance so let me try to test world's level three knowledge here we go put them on the spot so if we are VA Engineers not just normal Engineers how do what tests can we do to be able to detect residents so um as VA Engineers the most common tests that we usually employ for to confirm for resonance is a run-up coast down with a taco we want to use that to get phase reference to understand that when we go through a critical speed are we getting a 180 degree phase shift of course that that's what we like to use a good test for guys that don't have that equipment as like we said earlier you know cut the speed see if the vibration disappears very quickly but once we've confirmed that we have got a resonance we can then go to bump testing to try work out what part of the structure may be resonating usually it's just actual bit with the gearbox it was a gear was it it was actual gear yeah exactly so again that's another thing with the taco and obviously the run-up coast down is is really really good test to confirm it because when you go through that response spacing the response frequency and the critical speed or resonance or force and frequency they will match and be in Phase but as you go through that period it will lag then it'll lead and it'll go through that 108 degree shift and basically what we're doing is with the taco is just measuring the relative well not the relative the absolute phase difference between that them two signals yeah if that makes sense and when we go through that that's complete confirmation but sometimes you'll get machines that Ram so quickly yeah or shut off so quickly that's really difficult to be able to capture that actual resonance scenario between the two so that can be a really difficult scenario as well and we've had instances where we've not been actually been able to even capture it because so how quick it stops or how how quick is history ramp us up if it's not an inverter it's very difficult to get them events in as well so another thing obviously just to add a few points on the bump test bump testing is really really good and all we're doing is putting force in frequency yeah hitting something to see what the responses and all the responses is that machine vibrating that yeah we're hitting it with a special Hammer essentially that connects to the analyzer and when we do that we're able to inject frequencies at all the frequency range yeah and then we're going to basically here looking to see what the response is across a frequency range and that response will allow us to understand how is that machine vibrating from that response at its natural frequency so once we've taken that natural frequency we can have a look at the force and frequencies and pose on it whether that's running speed or yeah or or rotational frequencies and we're able to then see do they coincide or do they not so that's another method as well and um trying to think of any other tests that can be done that we do I mean there are other things that you can do like like bump testing when it's offline and stuff like that yeah we've never really done anything I'm sorry we've never really done that type of thing I think it's called there this is like reverse bump testing when the machine is running and then you can kind of do tests but we've never really been in the scenarios I think they're the two core tests that we would want to try and do if we were looking for a residency 100 100 but again not we haven't always got the tools for these type of yeah exactly and again if you know if anyone needs any help with these issues or problems get in touch with us because we love problem solving I love a resonance issue if I'm on this like I love data collection where you've got Mass data collection but I'll be honest when you're looking at just one machine trying to solve a problem you're trying to solve it it's really exciting as well so guys thank you for tuning in um to another podcast about resonance I hope you guys have enjoyed it um I don't know really what we're gonna go on next I don't know maybe do a poll we'll do a poll we'll do a poll we'll get some ideas out there what do you guys want to hear you let us know anyway guys thank you tuning in and uh yeah I hope you all have a great week we'll catch up with you soon

Channel: Maintain Reliability

Views: 176

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Id: U-zxLo_SEck

Length: 30min 50sec (1850 seconds)

Published: Mon Jul 03 2023