How to calculate two bar

1.

Two force bar: refers to a bar only at both ends of the force, and in a state of balance

Two force bar is also called two force bar. No matter how strange the shape of the component is, as long as the force is applied at two places, for example, the component in Figure 3 only bears the force at two circular holes C and D, it is a two force component, and the action line of the force passes through the action point of the two forces. If the gravity of the component has to be considered, it is no longer a two bar

In addition, it is impossible to have a couple, which is the misunderstanding caused by the absence of circles at a and B in Figure 1. No circle is often understood as a fixed end, and the end will be affected by the reaction couple of the wall. The force of the two bar must be along the action point of the two forces, which is the inference of axiom plus constraint property (not the two bar principle)

extended data

< 1, two bar constraint

two ends connected with other objects through spherical hinge or plane cylindrical hinge without mass is called two bar constraint. From the constraint analysis of spherical hinge or plane cylindrical hinge, it can be seen that the two bars are only constrained at both ends, and they pass through their respective geometric centers. If the two bars are in equilibrium, the two forces must be equal in magnitude, opposite in direction and collinear

two bar constraint is different from flexible cable constraint, it is not one-sided constraint. If the bar is straight, cut it off. According to the equilibrium condition of the cut-off part, there must be a force on the cut-off section, and the sum of the two forces constitutes a balance force system. Force and internal force of member. They are equal in size and opposite in direction

The pulley shaft o is installed on a light wooden pole B, a light rope AC bypasses the pulley, the end a is fixed on the wall, and the rope remains horizontal, and a heavy object is hung on the end C

The angle between

Bo and vertical direction θ= forty-five °， The system is in balance. If the position of the pulley remains unchanged, change the position of the pulley θ The size of the pulley is affected by the elastic force of the wooden pole, regardless of the angle θ When it gets bigger or smaller, the elasticity will not change

2.

The two ends of the slender rod are connected with other components by hinges; In addition to the possible load at the hinge, there is no load (force, couple) on the rod, which is called two force rod

stress characteristics: the forces at both ends are equal in magnitude and opposite in direction, acting on the connecting line of two hinge points

two bars are common in truss structures, if the joints of truss are smooth hinge points. The axis of each rod is straight and passes through the center of the hinge. Both the load and the bearing reaction act on the joint. Then all members of the truss are two force members

Extended data:

a member whose two ends are connected with other objects through spherical hinge or plane cylindrical hinge without considering mass is called two bar constraint. According to the constraint analysis of spherical hinge or plane cylindrical hinge, the two bars are constrained only at both ends, and their action lines pass through their respective geometric centers. If the two bars are in equilibrium, the two forces must be equal in magnitude, opposite in direction and collinear

if the bar is straight, cut it off. According to the equilibrium condition of the cut-off part, there must be a force on the cut-off section, and the sum of the two forces constitutes a balance force system. Force and internal force of member. They are equal in size and opposite in direction

3. First of all, the definition of 2-bar in the book is 100% right. In fact, this problem is done in this way. The AB component is divided into simple "rod" AB, support B and pulley a, so that AB is only subject to two "action" members: the reaction force given by pulley A and the support reaction force of support B. It's in balance, so it's a two force bar, and the reaction force from the AB bar of pulley a hand, the supporting force from the AC bar, and the pulling force of the weight are in balance

it is a very important skill to consider the hinge, support and member separately, which will be used frequently in the future, so please understand. I don't understand. Please keep asking.

4. Two force bar means that two forces act on a bar and can make it in a state of equilibrium
the two forces on two force bar are a pair of balanced forces

5. The two ends are smooth hinges, and the dead weight of the bar is not considered. The straight bar or curved bar without force in the middle is a two force bar

6. Yes. Only a, C hinge force, two forces, two force bar.

7. The two force bar is hinged at both ends (draw a small circle at both ends of the bar), and no force is applied to any part of the bar except the two ends. Those bars (both ends are hinged) which are not subject to external force and do not consider gravity are two force bars. The force direction of the two force bars can only be along the direction of the bar, the size is equal, the direction is opposite, and the action point is the bar end.

8. I've been reading this topic for a long time, but it turns out that it's the number of zeros. Sorry, I haven't learned theoretical mechanics. I collected relevant information on the Internet, analyzed and judged that the C white eraser should be zero rod, and the force direction of other rods was drawn on the graph. I judged that the resultant force of all x and Y directions was 0,

9. Generally, it is not necessary to judge the tension and compression, and set the force of the two levers as positive (tension).
if the result is positive, it is tension, and if it is negative, it is pressure.
beginners are always used to judge the positive and negative, which is futile and meaningless

10. Theoretical mechanics is the simplest! Two force bar refers to the action of only two forces. The direction of the force is along the bar, such as the supporting stick! Push both ends outward along the stick, or pull inward along the stick!