OptiStructではさまざまなひずみの組み合わせタイプが利用可能で、デフォルトは “Absolute maximum principle strain (絶対値最大の主ひずみ)”です。一般的に脆性材料には "Absolute maximum principle stain"が推奨されますが、延性材料には "Signed von Mises stain"が推奨されます。符号付きパラメータの符号には最大絶対値主値の符号が用いられます。
Make sure the task Import File is selected in the
Fatigue Analysis tree.
For the Model file type, select OptiStruct.
Click the Open model file icon .
A Select File browser window opens.
Select the ctrlarm.fem file you saved to
your working directory and click Open.
Click Import.
This loads the control arm model. It includes a whole definition of two
static subcases, elements sets, and material static properties,
etc.
Click Apply.
This guides you to the next task Fatigue Subcase of the Fatigue Analysis
tree.図 7. Import a Finite Element Model file
モデルのセットアップ
Create a Fatigue Subcase
Make sure the task Fatigue Subcase is selected in the Fatigue Analysis
tree.
In the Create new fatigue subcase field, enter fatsub_fpmtut.
Click Create.
For the Select existing fatigue subcase field, select the newly created fatigue
subcase fatsub_fpmtut.
fatsub_fpmtut is selected as the active fatigue
subcase. Definitions in the following processes (analysis parameters, fatigue
elements and properties, loading sequences, etc.) will be for this
subcase.
Optionally, you can choose to create all fatigue solver cards (such as
FATPARM, FATDEF,
FATEVNT, PFAT etc. that are created in
subsequent steps) in a separate include file. For this, you should select the
check box Create include file for fatigue solver cards
(optional).
Click Apply.
This saves the current definitions and guides you to the next task
Analysis Parameters of the Fatigue Analysis tree.図 8. Create and Select Active Fatigue Subcase to Process
Apply Fatigue Analysis Parameters
Make sure the task Analysis Parameters is selected in the Fatigue Analysis
tree.
Select the following options:
Analysis type
E-N
Stress combination method
Signed von Mises
FEA model unit
MPA
Mean stress correction
SWT
Rainflow type
STRESS
Plasticity correction
NEUBER
Enter the following values:
Certainty of survival
0.5
Gate
0.0
Click Apply.
This saves the current definitions and guides you to the next task
Elements and Materials of the Fatigue Analysis tree. For details, consult the
Altair HyperWorks2025 help.図 9. Fatigue Analysis Parameters Definition
疲労要素と材料の追加
Fatigue AnalysisツリーでタスクElements and Materialsが選択されていることを確認します。
Add Materialをクリックします。
Material Dataウィンドウが開きます。
Material名にAluminumを選択します。
Stress unitがMPAにセットされていることを確認します。
Ultimate tensile strength (UTS)に、600と入力します。
EN曲線を定義するInput methodにEstimate From
UTSを選択します。
図 10. 材料データ定義
Show EN curve definitionアイコンをクリックします。
EN 材料パラメータの生成方法を紹介するEN method descriptionウィンドウが開きます。図 11. ENカーブ材料定義
Closeをクリックします。
Material TypeにAluminum and Titanium Alloysを選択し、Estimateをクリックします。