5.10. psi.loadcase¶
Each loadcase consists of one or many different types of loads applied to the piping system at once. For instance, the sustained case for a system without springs consists of the weight(W) case along with a pressure case(P1). Both these loads are first applied to the underlying finite element model and the solution is generated for that particular case. This is a primary load case since it is composed of primary loads.
A load combination case consists of one or more primary load cases combined using a specific combination method. The solution vectors from the primary load cases are added, subtracted, etc., in order to produce these kind of secondary load cases.
A loadcase may consist of primary loads such as Weight, Thermal, etc., or it may be a be a combination of two or more secondary (ie. result cases) combined together.
The displacement, support reactions and internal force results for the loadcase are stored internally in the load case object. Note that properties with units for different values are stored separately and combined on the fly.
5.10.1. LoadCase¶

class
psi.loadcase.
LoadCase
(name, stype='sus', loadtypes=[], opercases=[])¶ A set of primary load cases consisting of different types of loads and the operating case the load belongs to.
Example
Create a deadweight loadcase.
>>> w1 = Weight('w1', 1) >>> p1 = Pressure('p1', 1) ... >>> lc1 = LoadCase('lc1', 'sus', [Weight, Pressure], [1, 1])
Note
The weight and pressure load have been defined for operating case 1.
Attention
The loads for a given case must be unique. In other words, the same load cannot be specified twice. An equality check is performed based on the load type, name and operating case it belongs to.
Methods

__init__
(name, stype='sus', loadtypes=[], opercases=[])¶ Initialize self. See help(type(self)) for accurate signature.
Properties

property
movements
¶ Return the nodal displacement results array.

property
reactions
¶ Return the nodal reaction results array.

property
forces
¶ Return the force reaction results array.

5.10.2. LoadComb¶

class
psi.loadcase.
LoadComb
(name, stype='ope', method='algebraic', loadcases=[], factors=[])¶ Combine primary loadcases using different combination methods.
Note
Combinations pull stored data from loadcases on the fly and do the necessary combination operations.
Attention
A loadcase and a loadcomb are derived from the same basecase and so they have the same namespace when it comes to name.
Methods

__init__
(name, stype='ope', method='algebraic', loadcases=[], factors=[])¶ Create a loadcomb instance.
 Parameters
name (str) – Unique name for load combination object.
stype (str) –
Type of code stress. Defaults to sustained stress.
HGR  Hanger load case
HYD  Hydro load case
SUS  Sustained stress case
EXP  Thermal expansion stress.case
OCC  Occasional stress case
OPE  Operating stress case
FAT  Fatigue stress case
method (str) –
Result combination method.
Algebriac  Disp/force results added vectorially. Stresses are derived from the vectorially added force results.
Scalar  Disp/force results added vectorially similar to the algebraic method. Stresses are added together.
SRSS  Square root of the sum squared. Direction independant.
Abs  Absolute summation.
Signmax  Signed max.
Signmin  Signed min.
loadcases (list of loadcases.) – List of load cases.
factors (list of numbers.) –
A list of factors corresponding to each loadcase.
Note
If a factor is not given, a default value of 1 is used. Also, the number of factors must match the number of loadcases.
Properties

property
movements
¶ Return the combined nodal displacement array.

property
reactions
¶ Return the combined nodal reaction array.

property
forces
¶ Return the combined nodal forces array.
