Statics - Chapter 6 (Sub-Chapter 6.6) - Frames and Machines
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- čas přidán 7. 08. 2024
- Statics
Chapter 6.6
Frames & Machines
(OMG it is them Machines!!)
We cover how to solve problems for frames and machines, especially how to draw the free body diagram for different types of frames and machines.
The objective for this section, Students will be able to:
a) Draw the free body diagram of a frame or machine and its members.
b) Determine the forces acting at the joints and supports of a frame or machine.
Among the items that will be covered:
- What are frames and machines, the definitions
- Steps for analyzing frames and machines
- Identifying two force members
- drawing free body diagrams
- equation of equilibrium
- Examples of problem solving for frames and machines problems
- Various examples of different frames and machines, and how to draw their free body diagrams
Frames and Machines problems are always quite interesting in the final exam, as many students seems to be quite intimidated by such problems. Just by looking at the diagram of the structure, is enough to send shiver into the students' spines and enough to make them concede defeat and not even attempting to answer the question.
In this lecture I would like to illustrate to the student that these questions are not as difficult as they may think. Sometimes the solution is so simple that it sometimes shocks the students. The thing is, if you never tried and attempted such question prior to the exam, you will never realize that it is much easier that it seems. The structure that seems complex will continue to intimidate you, perhaps due to fear of the unknown.
Well, if you are taking engineering course, you shouldn't actually let some diagram of simple frames or machines to intimidate you, right?
One significant step is to be able to draw the free body diagram. If you are able to correctly draw the free body diagram, then half of the battle is already won. What is left is just equation of equilibrium and solving the equations. Well, sometimes simultaneous equation can happen, but that is just part of life, I guess.
If you are searching for frames and machines statics, this is the video for you. Hopefully it helps =)
Playlist for Statics Lecture Videos as well as Tutorial Videos:
• STATICS - Lecture & Tu...
Lecture Slides for the Lecture Videos:
drive.google.com/drive/folder...
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Statics is the branch of mechanics that is concerned with the analysis of loads (force and torque, or "moment") acting on physical systems that do not experience an acceleration (a=0), but rather, are in static equilibrium with their environment. When in static equilibrium, the acceleration of the system is zero and the system is either at rest, or its center of mass moves at constant velocity.
Assalamualaikum Dr, for 35:57, I think there should be a weight at one of the members which has point G on it (centre of gravity). Should we draw the arrow and write down the weight ?
Also Dr, for 38:11, why didn't we need to draw the member BC (a 2 force member) that connects between the 2 pulleys ?
yes you are correct, the weight force should be drawn and labeled
@@sayhan3631 if the question ask for FBD for all component, then it should be drawn...
if we just need to draw FBD for the use of calculation, two force member are not compulsory as the point corresponding to both end of the two force member in the 2 FBD involved will be in corresponding to each other
@@SaifuddinRehan Thank you Dr, also in 43:08, the FBD of pulleys C and D are not drawn. Is it because it is not needed ?
Dr, for 48:00, why don't we draw the action-reaction force at A with a 45 degree angle, instead of splitting it into its x and y components ?
THANK YOU DR !!!
Thank you!!! This video helped me a lot in this topic =)
you are welcome
hope you will have no problem to get the full mark for these kind of problems if it comes up in the exam
ye do
Tq Sir...I will pray for you and your family 😊
love your videos
thank you =)
alhamdulillah
thank you so much, i'm really helped by your video, i hope the best for you and your family, greetings from indonesia
you are very much welcome..
all the best in your studies too..
Thank you !
you are very much welcome =)
thanks man very good video
thank you very much
W.C salam brother. you are really great.
salam
alhamdulillah
any good that I have ultimately belong to Allah
but thank your for the compliment =)
something that is really confusing me is if when setting up a problem I should use internal forces or reaction forces to set up the the equation of equilibrium. In addition am I able to take a moment at a joint where there is only a tension force from a cable or do I need to have x and y reaction to be able to use momentum of equilibrium.
when you mentioned use internal forces, do you mean by using method of section? (where you cut off the member to have internal forces?)
you have to differentiate two separate things:
1. identify whether there is a moment reaction at a particular joint or not (for example pin joint will not have moment reaction, fixed support will have moment reaction)
2. applying equation of equilibrium, where summation of moment about a specific point is equal to zero (if the body is in equilibrium, then summation of moment will always be zero)
Identifying whether there are reaction forces and reaction moments is based on how each body is reacting to each other, and how each support prevent movement or rotation..
* This will affect you FBD
Equation of equilibrium is used to solve for structure in equilibrium, where for 2D you have summation of Fx, Fz, M all equal to 0, while for 3D you have summation of Fx, Fy, Fz, Mx, My, Mz all equal to zero.. (of course for summation of moment, you have to select where the point from which you calculate the moment from, this is not to be confused with the reaction moments mentioned above)
* This is after you already established your FBD
Hope this helps
If anything still unclear, do let me know
Thank you so much!
May I know the the video link that has solving part in the classroom?
the recording when i was giving the lecture and solving problem in the classroom are in this playlist:
czcams.com/play/PLHV_TAKwT1136mLWsutPPdD98rksQwWOn.html
however i think the class for this particular topic may be when my camera was becoming worse in term of failing to focus due to some scratch in the lenses, where unfortunately part of the recording became blur (you may check the respective recording of the respective class session)
Thank you so much!
Really good video, just had a question about the FBD at 56:27, is there suppose to be another T pointing downward on point C?
The text question asked to find Dx and the answer given in the back is Dx=18kN which is possible when taking the moment @ A
M@A=Dx(2)+6(0.3)-6(3.3)-6(3)*=0, the (6(3)*) being the tension I'm asking about.
ah yes, you are correct, there should be another force downwards at point C due to the tension from the cable.
thank you for the correction
(i wonder if it is possible to make any notes for the correction to the video)
i will check first for the other question you asked
("The text question" - did you mean the next question?)
@@SaifuddinRehan All good, and no it was a textbook question for chapter 6 that asked for reactions at A and D, this is one of the harder chapters but anything helps so thanks
@@AverageNeighbor Oh okay.. all the best, and hope you excel
how to know the directions of the reactions on the supports?
which type of support?
@@SaifuddinRehan pin connection
@@PLEASURE_MOKGANO for pin, we have to assume the direction, and after the calculation we will know the correct direction based on whether the answer is positive or negative value (positive means assumed direction is correct, negative means the actual direction is the opposite)
@@SaifuddinRehan ohhh okay Thank you so much Sir
@@PLEASURE_MOKGANO you are welcome
all the best in your studies