An engine exhaust manifold with conjugate heat transfer and structural deformation,
constructed of gray cast iron, initially at 300 K. The manifold outer surface has a
convective heat transfer coefficient of h = 6 W/m2 K at 300 K. The four inlets to the
manifold are held at 500 K with air as the fluid at 5 m/s.

Temperature history is available after linear transient heat transfer analysis. In order to
apply temperatures at multiple time steps to a structural analysis, one step transient
thermal stress analysis should be used. It provides displacement and stress history for the
duration of transient heat transfer.

In order to perform one step transient thermal stress analysis, you can define a linear
transient heat transfer subcase and a static subcase. TEMPERATURE case
control cards with HTIME keyword can be used in static subcase to choose
selected or all time steps to perform stress analysis.

Tip: One step transient
thermal stress analysis is to perform static analysis at all output time steps of
transient heat transfer analysis. Transient heat transfer analysis outputs temperature
results for every time step by default. This can result in a long simulation time and
create large result files. It is recommended to use the skip factor on
TSTEP card to write temperature results for a limited number of time
steps, with which one step transient thermal stress analysis can still capture the stress
history without added computational cost. When one step transient thermal stress analysis
is a nonlinear static subcase, the number of time steps should be further limited.
DLOAD is not supported.

FE Model

Element Types

CTETRA

The linear material properties are:

Property

Value

Young’s Modulus

1.38E11 PA

Poisson's Ratio

0.283

Initial Density

7817 Kg/m^{3}

Stress versus Strain curve defined for MATS1 (for NLSTAT analysis
only).

Results

From OSTTS (One Step Thermal Transient Stress) results, you can see the thermal results
from the subcase 1 (Thermal Transient) as in Figure 2 and the Stress
results from subcase 2 (NLSTAT) as in Figure 3.