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TEST CASE 9.1 BAR STRUCTURE LOADED BY CONCENTRATED FORCES IN THE AXIAL DIRECTION

Reference:

Perelmuter A.V., Kabantsev O.V. Analysis of structures with a changing design scheme, M.: Publishing House of SKAD-SOFT, 2015, p. 44.

 

Problem description:

The rack, rigidly restrained on both sides, consists of 4 sections, which are mounted in turn and loaded with concentrated longitudinal forces F. Determine the internal longitudinal forces N in the sections of the rack at each stage of assemblage.

 

Problem sketch:

 

Type of created problem:

Flat frame (X, Z, UY).

 

Geometric characteristics:

L = 1 m.

 

Material properties:

Bending stiffness: EI = 313.32 N·m2;

Axial stiffness: EA = 1000 N.

 

Boundary conditions:

Node 1 and 5: X = Z = UY = 0.

 

Loads:

F = 50 N.

 

Model description:

The system is modeled by 4 general finite elements of spatial bar (FE type is 10). Task is solved using two different approaches. The fist problem (option a) is done via classical staging. The second problem (option b) is modeled in the "Assemblage" system.

 

Calculation results:

Target value

Classical

staging (option a)

Accounting for the assemblage stages (option b)

1

2

3

4

N1-2, N

-75

-50

-100

-150

-150

N2-3, N

-25

-50

-100

-100

N3-4, N

25

-50

-50

N4-5, N

75

0

 

Internal forces N (option a), N

 

Internal forces N at the 4th stage of assemblage

(option b), N