Thermal

In many cases it is useful to consider the effect of thermal loading on a structure. Thermal loads can have two effects. A uniform temperature change causes the element to expand axially but induces no bending. However, the thermal gradient option defines a linearly varying strain through the thickness of the element so resulting in both axial expansion and bending. The positions of the temperatures are used to define the temperature gradient.

Either constant temperatures or temperature gradients can be applied to an element. In either case the temperature values specified are changes in temperature from ambient.

The temperature gradient is defined by applying temperatures at notional lower and upper surfaces. These need not coincide with the actual lower and upper surfaces of the element (which may not be known). The temperature gradient is then calculated from the top and bottom temperatures ( and ) and the top and bottom locations ( and ) as follows:

This temperature gradient applies to the section as a whole.

Definition

Name

The name is only used as a convenient way of identifying a load. Optional.

Beam List

This specifies a list of beam, bar, tie, strut or cable elements to which the thermal loads apply using any one of the forms detailed in “Lists”. The list may be a single item.

In sculpt: The beam list is set to the beam and bar elements in the current selection set. The beam list cannot be edited in the dialog.

Load Case

The load case in which the thermal load applies. The load case gives a way of grouping load effects together.

Type

The user has a choice of the type of loading applied to the elements.

• Uniform – a constant temperature rise applied to the whole element
• Gradient in y – a temperature gradient is applied in the element y direction
• Gradient in z – a temperature gradient is applied in the element z direction

Uniform Temperature

The temperature rise relative to ambient applied to the whole element.

Lower Surface, Temperature

For temperature gradients the temperature profile is defined by the temperature at two points, referred to as the lower and upper surfaces. This defines the location and temperature rise that applies in the negative y or z directions relative to the neutral axis. A negative value denotes a position “below” the neutral axis.

Upper Surface, Temperature

This defines the location and temperature rise that applies in the positive y or z directions relative to the neutral axis.