805
However , inclusion of carbon fiber into the feedstock caused internal voids inside of the beads responsible for stress concentration , resulting in failure at lower stresses .
 material: inclusion; material: carbon fiber; material: feedstock; concept or principle: internal voids; process characterization: beads; process characterization: stress concentration; concept or principle: failure
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: 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:
 material: inclusion; material: carbon fiber; material: feedstock; concept or principle: internal voids; process characterization: beads; process characterization: stress concentration; concept or principle: failure