Checking elements 7, 8 and joint 7-8 (tube-in-tube) by FEA (ANSYS) — example

1. Analysis model and input data

Analysis model

Loading diagram in the XYZ coordinate system of the ATD

Analysis model (FEA) in ANSYS

Geometric parameters in ANSYS

Input data

Forces: F_X = 1500 N, F_Y = 300 N, F_Z = 700 N.

Moments: M_X7 = 75000 Nmm, M_Y7 = 452000 Nmm, M_Z7 = 33000 Nmm.

Geometric parameters: L₇ = 115 (105) mm, L₈ = 85 (95) mm; L_7-8 = 60 mm; h₇ = 50 mm, t₇ = 5 mm, h₈ = 60 mm, t₈ = 5 mm.

Material: S235, weldable general-purpose steel.

Operating constraints: temperature T = (−30…40) °C.

Parameters of the ANSYS model

Forces: F_x = F_Y = 300 N, F_y = −F_Z = −700 N, F_z = F_X = 1500 N.

Moments: M_x = M_Y7 = 452000 Nmm, M_y = M_Z7 = 33000 Nmm; M_z = −M_X7 = −75000 Nmm.

Geometric parameters: H_e = 60 mm, V_e = 60 mm, H = 50 mm, V = 50 mm, H_i = 40 mm, V_i = 40 mm; FD1 = 30 mm and FD4 = 55 mm for Body2; FD1 = 85 mm and FD4 = 30 mm for Body1.

Material: S235, weldable general-purpose steel, with σ_at = σ₀₂/c = 235/1.3 = 180 MPa (since the FEA model is more accurate, a lower safety factor c = 1.3 was adopted than for the classical, less accurate design models); allowable contact stresses: σ_as = 90 MPa, the allowable steel-on-steel normal crushing stress, and τ_as = 45 MPa, the allowable steel-on-steel tangential contact stress.

Viewing the support (fixed) zone and the applied forces and moments

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2. Results

Viewing the forces in the reaction zone

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Viewing the displacements

🖱 → the model appears.

Viewing the stresses

Equivalent stresses on the global model

🖱 → 🖱 (marks local stress values at points) → [move the cursor and 🖱 click the point on the model where the stress value should be shown]; to delete a local value: 🖱 (Label) → [🖱 select the value, then press the Delete key];