# What is Structural mechanics: Definition and 25 Discussions

Structural mechanics or Mechanics of structures is the computation of deformations, deflections, and internal forces or stresses (stress equivalents) within structures, either for design or for performance evaluation of existing structures. It is one subset of structural analysis. Structural mechanics analysis needs input data such as structural loads, the structure's geometric representation and support conditions, and the materials' properties. Output quantities may include support reactions, stresses and displacements. Advanced structural mechanics may include the effects of stability and non-linear behaviors.
Mechanics of structures is a field of study within applied mechanics that investigates the behavior of structures under mechanical loads, such as bending of a beam, buckling of a column, torsion of a shaft, deflection of a thin shell, and vibration of a bridge.
There are three approaches to the analysis: the energy methods, flexibility method or direct stiffness method which later developed into finite element method and the plastic analysis approach.

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1. ### I Expansion-Collapse cycle in cosmological structures?

Concerning cosmological structures (like galaxies, clusters of galaxies, gas bodies, superclusters...etc) if the elements that make them are close enough they will be attracted towards each other by gravity. Contrarily, if they are sufficiently far apart they will get further away following the...
2. ### Structural Mechanics Distinction Task

To find axial load , 5m / 6m = 0.83 Arc tangent , tan-1(0.83) = 39.69 Cosine of the force , Cos(39.69) = 0.77 Sine of the force , Sin(39.69) = 0.64 Axial load in the vertical direction , (200kN/m X 6 = 1200kN / 2 = 600kN + self weight of 6kN = 606kN) So 606kN X 0.77 = 466.62kN Axial load in the...
3. ### Structural mechanics: Distributed forces on a structure

Problem Statement: What's your result of ##X_A##? I find mine is different from the standard answer. Relevant Equations: My answer for $$X_A =5 kN$$ Problem Statement: What's your result of ##X_A##? I find mine is different from the standard answer. Relevant Equations: My answer for X_A...
4. ### Stiffness matrix for elastic materials

For an anisotropic material, is there any way to analytically determine the elements of the stiffness matrix? For orthotropic and isotropic materials, there are analytical expressions relating the stiffness matrix elements to the elastic modulus and poisson's ratio, but I do not believe this...
5. ### Torsion in thin-walled members

is T=2*q*A formuala valid for both open thin-walled and closed thin-walled members, where T is torque, q is shear flow, and A is the Area.
6. ### Support reactions of a rigid, rectangular steel frame

Homework Statement Solve for support reactions of a rigid, rectangular steel frame sitting on rubber pads at the four corners (See attached), when a shear force and a moment is applied at some point on the frame. All the known variables are shown in black while the unknown are in red. It is a...
7. ### Should I learn fluid mechanics or thermodynamics

I am graduate student from structural mechanics of solids and need to learn 1 course from fluids and thermal group which includes fluid mechanics or thermodynamics+heat transfer. I am unsure which one would be better to learn, especially which would be helpful in future for solid mechanics. Can...
8. ### Physical interpretation of the "total potential energy"

The principle of minimum total potential energy is frequently used in solid mechanics as an elegant way of deriving the equilibrium equations for an elastic body under conservative forces. This method states that out of all the possible displacement fields that fulfill the boundary conditions...
9. ### Importing Mechanical Apdl geometry in Ansys Workbench

hi.. i want to import only the geometry defined in mechanical apdl into ansys workbench so that i want to have the freedom to change the geometry and meshing whenever i want to. thankyou
10. ### How to Solve Support Reaction (Virtual Work)?

Hey guys, I was revising using some past papers for my structural mechanic module when I realized that I don't know how to do this problem: https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/83/83583-240450b2eac78c09f31d35a531383268.jpg If it was for the deflection of node...
11. ### Structural Mechanics in Reactor Technology (SMiRT)

The SMiRT conference/symposium has been an important venue over the decades for folks involved in structural mechanics applied to nuclear power systems, from fuel and core components, to large components like pressure vessels, piping, heat exchangers, and related equipment, up through...

Homework Statement Hello, I am trying to model an arm mounted perpendicular to the straight mechanical column. An arm can be translated in horizontal direction by a gear which engages with the bottom of an arm such that it applies no force in vertical direction to the arm. And finally there is...
13. ### Finding the shear stress and angle of twist in hollow shaft

MODERATOR NOTE: THIS THREAD WAS ORIGINALLY IN ANOTHER FORUM, SO THERE IS NO TEMPLATE. I have a hollow shaft made of a titanium alloy, Shear Modulus "G". The shaft has a wall thickness of 3.2mm and an inner diameter of 20mm. The shaft looks as show in the attached image. A torque T of 232 Nmm...
14. ### COMSOL - Structural Mechanics - Membrane - vibration without input?

I've just got a quick question that hopefully someone can answer. My question is - why does the membrane in COMSOL vibrate without you telling it to? Here are some specifics if required... In COMSOL here are my setup details: - Physics: (3D) Structural mechanics - Membrane Study...
15. ### Structural Mechanics. bending moment and bending stress

[b]1. Homework Statement [b/] A timber beam, with rectangular cross section (h × b) is reinforced with additional full width (b) steel plates. There is a plate of thickness t securely connected on the bottom and a plate of thickness 2t on the top of the timber to ensure composite action in...
16. ### Exploring the Effects of Scale Analysis on Structural Mechanics Problems

Hi there, I am trying to solve a structural mechanics problem. I am doing so by two methods. On one hand, I am using a F.E.A software (ANSYS) to get me the solutions. At the same time I am solving the problem analytically. The issue is that ANSYS is solving the problem using a diferent theory...
17. ### Structural Mechanics - Statics / Truss

Homework Statement The simply supported timber foot bridge shown in figure 5 spans 7 metres and, as shown, is carried by two Engineering grade Douglas Fir beams. The uniformly distributed load due to the self weight of the foot bridge and beams is 96 kg/m. The bridge is required to carry a...
18. ### [Structural Mechanics] Conceptual Questions - Mechanisms & Plastic Analysis

Homework Statement Determine the failure mechanism and plastic moment for the following structure, using either the upper bound or lower bound theorem for plastic analysis. Picture (There is a physical hinge in the middle of the structure) Homework Equations Internal Work = External Work...
19. ### Structural Mechanics: Tapered Cantilever Beam with Varying Depth

Tapered cantilever beam with varying depth structural mechanics question help pleas?? [b]1. A tapered cantilevered beam of length 1000mm is fixed at the left end and carries both an upward load 400N and a positive moment (M) at the free right end. The out of plane thickness of the beam is...
20. ### Solve Structural Mechanics Qs 3 & 6 on PDF Files

can anyone please solve the following quastions on the attached PDF files number 3 and 6?
21. ### How can I solve this structural mechanics problem accurately?

I've been trying to solve a structural mechanics problem from the book Mechanics of Materials, but the results I acquired weren't very satisfying. Here it is Homework Statement [PLAIN]http://img42.imageshack.us/img42/4375/p17n.jpg Homework Equations Average Stress: \sigma= F/A...
22. ### Finding Equations for Simple Structural Mechanics Problems

I'm out of college for decades, and all my "handbooks" and college books have been packed away and inaccessible for some months. I need a source, or the equations as follows [all very simple, fundamental stuff; Chap One in "Strength of Materials", so to speak] 1] Beam supported both ends...
23. ### Getting Started: Solving Joint Problems in Structural Mechanics

Homework Statement See Attachment Homework Equations The Attempt at a Solution Im not really sure how to get started. I understand the method of Joints, and all the solved examples I can follow. I started by analyzing the support reactions, and I am stuck already. There is...
24. ### Structural Mechanics: Solving Shear Force on a Cut Beam

hi there any 1 know how to work out shear force ona cut beam ? i got the str3 web page problems!