PSI - Issue 42

Takumi Ozawa et al. / Procedia Structural Integrity 42 (2022) 730–737 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

733

4

2.2.2. Parameters for optimization In this study, the shape and location of LC is determined by seven parameters, compression area ( S ), aspect ratio ( a ), distance from the future crack tip ( d ), and corner dimension ( w N , w L , h N and h L ). Fig. 4 shows the definition of these parameters and LC condition for each param eter’s value. As shown in Fig. 4(b), many LC conditions can be described by changing these parameters. The authors are of the view that these parameters can describe almost all rational LC conditions which compress at once and of which shape is solid. 2.2.3. Constraint condition The authors set constraint conditions in the applied load and pressure, i.e., load divided by compression area. With regards to load, the upper limit was set as the value of 1000 kN with considering the load capacity of the general testing machine. Regarding pressure, the upper limit was set as the value of 1600 MPa, which is strength of a general tool steel, 2000 MPa, multiplied by a safety factor, 0.8.

EĞdžƚ ƉŽŝŶƚ

ϯ

Ϯ

ϭ

ĂůĐƵůĂƚĞĚ ƉŽŝŶƚ

/

KďũĞĐƚŝǀĞ &ƵŶĐƚŝŽŶ͕ K͘&͘ WĂƌĂŵĞƚĞƌ

Fig. 3. Process of Bayesian optimization

b

a

ŽŵƉƌĞƐƐŝŽŶ ĂƌĞĂ͗ S ƐƉĞĐƚ ƌĂƚŝŽ͗ a

w N

100

d

h L h N

w L

F ig. 4. Parameters for optimization: (a) Definition of parameters; (b) LC condition for each parameter’s value.