8688
Hence , the upper and lower bounds for fatigue life prediction were introduced based on the strongest and weakest part build directions or raster orientations of 3D printed materials .
 fatigue life, build directions, raster orientations, 3D printed
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: manufacturing standard, machanical property, manufacturing process, material, engineering feature, process parameter, machine or equipment, application, process characterization, enabling technology, biomedical, concept or principle 
Text: {0} 
Answer:
 fatigue life, build directions, raster orientations, 3D printed