University Structural Mechanics, College Structural Mechanics 2 Topics Explained in Detail

First of all, it is better to be unified when assuming the unknown direction of the reaction, such as unifying upwards and right positives.

Your question: In the beginning, you can set clockwise as positive and counterclockwise as negative as the direction of the force, and so on.

When the moment of point A is balanced, the distributed force shown in the figure is a clockwise moment to point a, so the moment of point A (not necessarily understood as q) caused by the distributed force takes a positive value; When the moment at point d is balanced, it is reversed, so a negative value is taken. As long as you remember the direction of the plus and minus signs you assumed earlier, and judge the combination one by one, regardless of the known and unknown forces.

After proficiency, there is no need to stick to the direction in front of you, when taking the moment at each point, directly list the first term as positive, and then take the positive when the direction of the moment caused by the first term is the same, and take the negative when it is the opposite. Column equations are solved.

Finally, the meaning of positive and negative is the same as the hypothetical direction, and the negative is the opposite, so you must pay attention to the direction of your own hypothetical force.

The best universities and universities in mechanics: Peking University, Tsinghua University, Beijing University of Aeronautics and Astronautics, Dalian University of Technology, Harbin Institute of Technology, Shanghai Jiao Tong University, Nanjing University of Aeronautics and Astronautics, University of Science and Technology of China, and the national key disciplines of its mechanics major.

Best Universities and Universities for Structural Engineering: University of Science and Technology Beijing, Tianjin University, Dalian University of Technology, Southeast University, Guangxi University, Xi'an University of Architecture and Technology and Technology, Structural Engineering, two key disciplines.

You can specify the positive and negative by yourself, for example, you can specify that the moment around the moment is positive clockwise and negative counterclockwise.

Summary. Hello, I found here for you, University Structural Mechanics 2, the basic system is to add a steel arm at c The basic unknown quantity is the angle of the rotation of c The basic equation: k11δ1+f1p=0k11=3ei f1p=-9 2 (.

That's the topic. Hello, here for you to check the socks to inquire, university structural mechanics 2, the basic system is bright for adding a steel arm at c The basic balance smile is the angle of the unknown quantity c The basic equation: k11δ1+f1p=0k11=3ei f1p=-9 2 (.

Related information: University structural mechanics tension on the bending moment diagram on that side, and then Tong Tong used to make the upper part of the beam tension negative, the lower part of the tension is positiveThe first problem is that the load is evenly distributed and acts downward, so the lower part of the beam is under tension.

The second question is that the bending moment at the point of action of the concentrated force is zero, so as to judge that the bending moment on the left is zero. Loose wheel early.

Three sections, arches, trusses, beams. The arch part is relatively simple, mainly a triangular arch. The truss part masters the node method and the cross-section method, especially the cross-section method, and the selection of the cross-section is a technical activity.

There are more beams. Force method, how to create a fictitious force, what structure can be simplified to create less force. The displacement method, whether to use angular or linear displacement.

The torque distribution method is a completely brainless method of problem solving. If you learn mathematics well, you can see that some parts of structural mechanics are pure mathematical problems. There are also some things like the degree of freedom of the system, the influence line, which is just like that, and when you master it, it feels the same as drinking water.

Finally, I want to say that if you really learn the mechanics of knots, you will only feel that you have not learned mathematics well. Personally, the humble opinion of the undergraduate period is to let you know what structural mechanics is and can solve those problems. Develop your ability to solve simple problems.

Especially a discipline as centuries-old as structural mechanics. If you are really interested in digging deeper, first learn mathematics, then learn theoretical mechanics, material mechanics, elastic mechanics well, and look back, the purpose of structural mechanics is to solve the displacement and internal forces of the structure under the action of loads (static load, moving load, support displacement and thermal stress), and judge the safety, functionality and durability of the structure accordingly (of course, this is the task of the subsequent course). In order to solve the displacement and internal forces of the structure, it is first necessary to determine whether the structure is variable or invariant, because the variable system cannot be solved; In the invariant system, it can be divided into statically determined structure and superstatically determined structure, and the method of solving these two structures is different, and the static structure does not need material parameters to find the internal force, and the method used is generally simpler:

That is, the nodal method and the cross-section method, of course, the displacement of the required system still requires material parameters. However, when solving the internal forces of superstatically determined structures, the parameters of the material are required, and the methods are: force method and displacement method.

and the slight splash of water from the fountain in front of the building, and the flowers hanging their heads, all seem to be rehearsing a reality that they don't want to accept, and pulling out a memory that is difficult to erase.

The noisy cracking sound of transportation and the sound of panting footsteps are all hurriedly bidding farewell to the silent campus. It seemed so fragile at this time, as if if if you only touched a little, you would feel an inexpressible feeling. Lean beside the tree and watch the tree sadly shake off the leaves.

At that moment, I felt that people were like trees in the loss of gain, in the loss of loss.

Missing the run on the playground, every day in addition to the sea of books, is the tears, sweat, laughter on the playground, I feel that this other battlefield in addition to books, a place where miracles are born, shows the tenacity that goes further than hard writing. I used to feel that he had the happiness that we would never enjoy not playing, and there was a group of energetic figures jumping on him. But now the departure has become so close, and the breeze blows from the playground, bringing us the fragrance of the lawn and the taste of sweat, and it is also bringing us a different kind of farewell.

And now facing the dusty field, I can only smile bitterly. I don't want to enjoy the joy of running on the green field, so I can only endure the hardships of trekking in the wind and sand. We missed the wide field, but we got a resilient heart.

Missed the goodbye to every tree. Suddenly, the trees and flowers on the campus were remembered, and they came to them, only to find that they were not as sad as they imagined, and the texture on the bark of the tree would not be engraved after all, but that may be the most special expression of the tree, adding a greenness to your heart and a little less loneliness. The deep veins on the leaf are not only its aging, but also the most unforgettable memory of its contact with us.

But all this will eventually disappear without a trace because of the quiet fall of the leaf. Trees and people have the same sense of branches: instead of indulging in painful memories, it is better to welcome a new life and embrace a better tomorrow.

We miss the flowers and plants that we get along with day and night, but we get fresher than they last.

The students are silent among themselves, perhaps at this moment, only these things that we usually ignore are the most sincere feelings in our hearts, and it is an expression that transcends words.

Chew the bitter fruit that you missed, and a trace of treasure rises in the faint bitterness.

Structural mechanics is an ancient discipline and a rapidly developing one. The emergence of a large number of new engineering materials and new engineering structures has provided new research content and put forward new requirements for structural mechanics. The development of computers has provided powerful calculation tools for structural mechanics.

On the other hand, structural mechanics has also played a role in the development of mathematics and other disciplines. The emergence and development of the finite element method is closely related to the study of structural mechanics. In the field of solid mechanics, the mechanics of materials provides the necessary basic knowledge for structural mechanics, and elastic mechanics and plastic mechanics are the theoretical basis of structural mechanics.

In addition, structural mechanics and fluid mechanics are combined to form a marginal discipline - structural fluid elastic mechanics.

From a mechanical point of view, the main evaluation of the strength and stiffness of the structure is the strength and stiffness of the structure. The design of the engineering structure should not only ensure that the structure has sufficient strength, but also ensure that it has sufficient rigidity. The strength is not enough, and the structure is easy to break; If the stiffness is not enough, the structure is easy to wrinkle, or there is a large vibration, or a large deformation.

Wrinkles can lead to deformation and damage of the structure, vibration can shorten the service life of the structure, wrinkles, vibration, and deformation will affect the performance of the structure, for example, reducing the machining accuracy of the machine tool or reducing the efficiency of the control system.

Observing the natural structures in nature, such as the roots, stems and leaves of plants, the bones of animals, and the shells of eggs, we can find that their strength and stiffness are not only related to the material, but also to their shape. Many engineering structures are inspired by natural structures.

The calculated model should be the first case in the figure below, the de rod is at E with an orange fixed end to constrain the liquid line cracking, so there is a bending moment, but your diagram is wrong. The reaction force should be p 2 and the bending moment is calculated to be zero (not "non-existent", but the calculated result is zero).

In addition, if the structure is equivalent to the second case, i.e. the fixed end is not calculated by detaching it from the structure, then there is no bending moment as long as the support reaction force is calculated.

Finally, the E end can't be regarded as a fixed end of the shutdown, it should be that there is only a vertical constraint below him, and there is no horizontal one. It can only be regarded as a nominal or half fixed end.

In the problem, the number of members m=16 and the number of nodes n=10

The condition of m+3=2n is not satisfied. This structure is unstable.