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  1. CESSNA1

    ROAD COURSE PROFILES

    GREG: You are correct, I do not need 1 mm accuracy. The name "PERRYMAN" implies that the course is defined, perhaps in a spec, or std, or some other document. I realize that the "actual course" and the "defined course" can, and probably vary. I just want to find out how the course is...
  2. CESSNA1

    ROAD COURSE PROFILES

    CLOA AND GREG: Thank you for the your time and effort to respond, I sincerely appreciate it. The website listed by Cloa does not give the level of definiiton for which I am looking. For example is the profile flat or sinusoidal or somewhere in between. Greg, I did Email NATC asking for this...
  3. CESSNA1

    ROAD COURSE PROFILES

    HELLO ALL: Vehicle road testing can be done over predefined road profiles. The Perryman Profiles are often used. I am trying to find the definition of the Perryman Profiles. Does anyone have the profiles for the Perryman 1,2,3,4 road courses? I have searched the internet and have been...
  4. CESSNA1

    MOMENT DESTRIBUTION METHOD FOR SIMPLE FRAME

    JAE:Thank you for your response. The bending is about the flat side, as you noted. I understand your concern about space but I wanted someone to work the problem, in detail, and then scan and E-mail the results to me. I have the textbooks and I am muddleing through them But I would like...
  5. CESSNA1

    MOMENT DESTRIBUTION METHOD FOR SIMPLE FRAME

    JAE: Thank you for your response. You are correct. The 8" leg is flatbar that is 2" wide and .375" thick. The moment of inertia is: (1/12)*(2)*(.375^3) =.0088 This is part of a small bracket that fits on the front of a vehicle and I am trying to determine the loads and stresses involved...
  6. CESSNA1

    MOMENT DESTRIBUTION METHOD FOR SIMPLE FRAME

    HELLO ALL: It has been over 30 years since I have worked witn the moment distribution . I am really rusty. By the way this is not a homework problem this is a real world problem. Here is the problem I am trying to solve. A simple 2 dimensional frame with 8" legs and an 11 inch top cross...
  7. CESSNA1

    IMPACT DEFORMATION

    HELLO ALL: Here is my question: A bus (40000#) hits a auto (4000#) in the rear end at a low speed (10 mph) The strucural supports for the bike rack on the bus are deformed plastically. Is there a way to calculate/estimate the force on each of the two brackets? Cordially Dave
  8. CESSNA1

    SCREW FAILURE

    THANK YOU ALL FOR YOUR RESPONSES. UNCLESYD: I do not have the specification or the plating procedure. The environment is just ambient conditions. TXMEEN: The applied load is a shear load. A .125: X .5" aluminum bar with six .190" holes is positioned under the head and the screw...
  9. CESSNA1

    SCREW FAILURE

    RON: Thank you for your reply. There was a failure of six of these screws simultaneously. There is no information about other screw failures in similar systems. It is believed that in service these screws loosened and ultimately failed. The failures occured approximately 0.5 inches below...
  10. CESSNA1

    SCREW FAILURE

    HELLO ALL: Attached are two images of a 10-32 zinc plated steel screw that failed under a sidewise load. The load was applied under the head and the screw broke at the top of the threads in a rivnut. The part that bothers me is the hole in the middle of the screw that is seen in the endview...
  11. CESSNA1

    HINGED PLATE IN FREE FALL

    HANDLEMAN: Thank you for your response. I did not give specific numbers becasue I was looking for a solution that would be in general form. I was remiss in not stating that. Would you please give one or two sources for the numerical method I will need? Thank you again for your quick...
  12. CESSNA1

    HINGED PLATE IN FREE FALL

    HELLO ALL: This is a real problem. A uniform rectangular flat steel plate hinged on one side is held at an angle, theta (90<theta>0). The only force acting is earth's gravity. The plate is suddenly released and allowed to fall under th influence of gravity to the horizontal position. ignore...
  13. CESSNA1

    Basics

    DEAR UFJ: For 1) I assume that 1 and 2 are sine vibrations and the G value is peak to peak. Make sure you know how your acceleroometers are calibrated. Othwise you could be off by 1.414. The 30 hz vibration has a slightly smaller displacement than the 13 hertz but the 13 hz is for a longer...
  14. CESSNA1

    Vibration shaker

    ROCKETMOTOR: To arrive at the displacement is easier to show than to explain but here gos. The PSD has the units of G^2rms/Hz. The PSD value .03 or .06 in this case is the average of all the peaks around the center frequency (usually +/- 1 db). 1. Take the square root of the G^2 rms term...
  15. CESSNA1

    Vibration shaker

    ROCKETMOTOR: In general the lowest frequency will have the highest displacement. Assuming the PSD values are in G^2 rms/Hz the approximate amplitude at 3 hz is around .25 g's peak. This corresponds to a peak displacement of about 600 mils or 0.6 inch peak or 1.2 inches peak to peak. At 20 Hz...
  16. CESSNA1

    Vibration Test Fixture

    STOCKDAM: Vibration fixture design is a much an art as it is a design. I sugggest that you take the fixture design course offered by Technical Training Institue (TTI). They offer a bunch of great courses. Their website is www.tti4edu.com. The courses are terrific. Also, most of the classes...
  17. CESSNA1

    How to quantify the severity of multiple shock events

    Shockdesigner331: This looks like a ride quaity issue. There is an ISO Spec that addresses ride quality you may want to read it. I have one that is 2-3 years old. If you want I will send you a copy. Reply to dphall@sbcglobal.net with your mailing address. Is the customer looking for...
  18. CESSNA1

    Aircraft-mounted videocam mounting

    BOTONIST: Stabilized camera mounts are availabe. I suggest that you check with a TV station that has a helicopter or a an aerial video service that provides them. Regards Dave Hall
  19. CESSNA1

    Is Silicant rubber sealant OK at -40C?

    DIGGER2000: Be careful when using silicone compounds as an adhesive. In general their adhesive quanlities are poor. I have seen parts come apart becuase they were held with silicone adhesive and could not take the environment for which they were supposedly designed. Check it out first...
  20. CESSNA1

    Design of vibrating amusement ride

    ROBERTCASEY: It sounds like what you have is a classic spring-mass vibrating system. Did you model only the platfrom, or the overall system, or both? The mass(platfrom/people) are suspended on air springs. You need to replace the solid mounts with the spring constant of the air springs...

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