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  1. marellasunny

    Automotive Calculating the angular acceleration of a swivel seat

    Angular acceleration of 0.034 rad/sec2 sounds about right for this application. I make the mistake of not considering the right acceleration time- just the 7.5 seconds, in fact the motors would accelerate, steady and decelerate in a trapezoidal fashion. This was very helpful.
  2. marellasunny

    Automotive Calculating the angular acceleration of a swivel seat

    We have an automotive swivel seat that turns from the initial seating position to the final position outside the vehicle (90 degree swivel in 15 seconds). We would like to calculate the torque required for rotating the seat along with the person. We have calculated the inertia of the movable...
  3. marellasunny

    500 kg Solar CSP reflector dish mechanism problem

    Thanks for the reply Nidum. Detecting if the drive is behaving abnormally would be possible only if I use a current sensor to sense actuator-block. By actuator-block I mean that some part of the mechanism in the system has malfunctioned/stuck. In this case, the motor driver would see a sudden...
  4. marellasunny

    500 kg Solar CSP reflector dish mechanism problem

    Hi JBA. I hope the photo above makes it clear to you where the swivel point of the dish exactly is. This is an eccentric rotation. I've marked in the photo where I would place the actuator and top-support assembly. The top-support assembly would be a prismatic mechanism with a rod moving inside...
  5. marellasunny

    500 kg Solar CSP reflector dish mechanism problem

    Hi Oz. We did not manufacture these dishes, so I'm not too sure on the material although I could take a guess. These are not SS, probably silver and copper coating on glass. Price of PV unfortunately does not have major effect on CSP. These are just reflectors and have no photovoltaic...
  6. marellasunny

    500 kg Solar CSP reflector dish mechanism problem

    I am currently re-fabricating solar concentrator dishes to allow for automatic tracking of the sun during the day and month. The industry term for these dishes is 'CSP' (Concentrated Solar Power). Task at hand: The CSP parabolic dishes are currently manually adjusted to the position of the sun...
  7. marellasunny

    Reliability of low-cost accelerometers in commercial applications

    Thank you for the reply. No this is not a critical application like aircraft systems. Although, if accelerometer did fail in my system, errors would accumulate over a period of few days and system positioning would become highly inaccurate. No safety issue though. The reason 2 cheap...
  8. marellasunny

    Reliability of low-cost accelerometers in commercial applications

    My question relates to the reliability of low-cost accelerometers (MMA7455,ADXL345 etc.) in commercial products with a expected life expectancy of 5 years or more. The tilt angle reading from the accelerometer will be used as a feedback parameter to orient a single-axis plate-reflector...
  9. marellasunny

    Linear actuator limit switch replacement/repair

    S2M implies surface mount? Then I'm thinking of using the 1N5408 as per the spec sheets. Yeah I see the smd diodes on top, numbers blackened out . Thanks for the tip. https://en.wikipedia.org/wiki/1N400x_general-purpose_diodes
  10. marellasunny

    Linear actuator limit switch replacement/repair

    Apologies for the late reply. The motor no longer works. Hopefully its because some passive component got burnt-up. 1 good thing that seems to have emerged is that I have come closer to understanding the inner workings of the linear actuator. Please find attached the pics with descriptions of...
  11. marellasunny

    Alternatives to varistors as overload protection at DC motor

    Thanks for the replies. FYI I managed to only get hold of 130V clamping voltage varistors. Nothing in the range of 18V is available. So, I'm thinking of connecting series-opposing 15V zener diodes instead. Is that okay? CWatters- "If you are concerned about something stalling/blocking the...
  12. marellasunny

    Alternatives to varistors as overload protection at DC motor

    Alternatives to varistors as overload protection at DC motor DC Motor here implies 12V linear actuator w/DC Motor that consumes 2.8A under loading condition. Pretty costly equipment. I'm using a L298N motor driver connected in parallel to run the linear actuator. The motor driver is run by a...
  13. marellasunny

    Linear actuator limit switch replacement/repair

    Linear actuator spec.: 400mm stroke, 6000N, 2 limit switches, 5mm/sec, 12V DC supply, BIBUS IP65 casing. One of the limit switches of my LA (Linear Actuator) seems to have burned out. This happened because I accidentally plugged the LA leads into the AC mains socket (my LA is rated to run at...
  14. marellasunny

    Automotive X shaped roof profile for small series car-production method

    Hi all! I need to decide on the production philosophy of an SEV(small electric vehicle) as a final part of my thesis project. Up until now, I have designed the package layout and body and performed a FE analysis (topology optimization) to arrive at a reasonable body-in-white structure. I did a...
  15. marellasunny

    Front crash with crumple zone: relative velocity calculation

    EURONCAP front crash test involves crashing a car moving at 64 kph onto a deformable barrier at 40% of the total vehicle width. According to the EURONCAP website, this is equivalent to two vehicles crashing into each other at 55 kph. How did they arrive at this figure? I presumed that the...
  16. marellasunny

    Superposition of loadcases in FEA software (with SPC+inrel)

    In case of a topology optimization (optimal material distribution), how do FEM software superposition different loadcases to arrive at one final result?
  17. marellasunny

    Superposition of loadcases in FEA software (with SPC+inrel)

    I am curious as to how finite element analysis software(like Hypermesh) go about superposition of loadcases(applied on the same model). I constrain my vehicle body for 1.loadcase (say bending) with the standard SPC's and constrain my 2.loadcase(say torsion) with Inertia relief constraints...
  18. marellasunny

    Calculation of the battery pack voltage for an EV

    Zoki: Specified power of motor is 93 kW. This apparrently is a AC motor, sorry for the wrong info. 93000/360V= 258 Amps. I get a feeling this a bit too much.
  19. marellasunny

    Calculation of the battery pack voltage for an EV

    I'm a Automotive engineer and hence lack the electrical engineering expertise that you might expect. This is related to a doubt I have in calculating the final battery voltage for an electrical vehicle. This is just a calculation query. I have a module consisting of 12 individual Li-ion cells...
  20. marellasunny

    10S4P with Lithium ion battery; Question on the calculation

    My build will be from time-to-time be posted in the Automotive engineering forums in Physics forums. I would love to document and share the information online but unfortunately my contract blocks me from doing so. Neverthess.......you'll find me in the AE forum :). Last question: What is the...
  21. marellasunny

    10S4P with Lithium ion battery; Question on the calculation

    I am planning to use the Panasonic NCR-18650 cylindrical cells for a BEV (Battery Electrical Vehicle). As it would be easier to buy ready-made modules, I have found a supplier selling a Li-ion pack that delivers 417 Wh(or in other words 11.6 Ah) at 36 V (something like what this guy uses...
  22. marellasunny

    Rear damper travel; Rear passenger packaging

    Actually, not much more to give than the diagram I have attached. I was hoping for some insights into rear damper packaging, for example: 1.Is the rear damper placed before/after the lower A-arm? 2.How much laterally to the centre do I place the damper?
  23. marellasunny

    Rear damper travel; Rear passenger packaging

    I am quite uncertain as to why the rear damper is inclined at a angle to the inside of the car. By doing so, does one ensure for rear wheel travel to be along a curved up/down path? i.e I am perplexed as most of the modern rear suspensions are multi-link and have their dampers inclined → This...
  24. marellasunny

    Why I failed an exam? (problem solving vs lecture note reading)

    True mal4mac. Engineers do look down on the humanities. It is a pity.
  25. marellasunny

    Is the condenser of a E-vehicle cooled by liquid circulation?

    I've noticed that a FEW of the electrical vehicles have no front grill. I am quite surprised that they do not have one, because the condenser of the AC unit needs to have heat taken away from it (in other words, the condenser needs a heat exchanger). So, in view of the fact that E-vehicles don't...
  26. marellasunny

    Electric vehicle component package ideation

    Thanks old jim. I have a simple question: Does the transfer of C.G DURING a crash pose any major disadvantage? It seems logical that when the C.g shifts during a crash in a direction where the passengers are sitting, then there is going to be blood. Am I correct? So,with this simple...
  27. marellasunny

    Electric vehicle component package ideation

    I think automotive engineers call weight reduction 'Topology optimization', although I haven't come across articles relating structure weight to vehicle handling yet. If I may say so, handling of an automobile has always been related to the roll centre height, am I correct? So,if I find a...
  28. marellasunny

    Electric vehicle component package ideation

    Inter'part' linking, very interesting approach to design. Will start using this in CATIA right away. Thanks.
  29. marellasunny

    Electric vehicle component package ideation

    I am in the design phase of a lightweight electric city vehicle with a capacity of 15kWh. I am at a stage where I am moving elements like Electric motors, tranmission, DC-DC converters, Inverters, Battery charger and battery pack in a CATIA software model. In-order to cater to the wide-range of...
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