ようこそ ゲスト さん
ランキング
アクセスランキング
ダウンロードランキング
サービス
パスワード変更
京都工芸繊維大学
学生成果物
学位論文
このアイテムのアクセス数:
2,397
件
(
2024-07-03
10:19 集計
)
このアイテムへのリンクには次のURLをご利用ください:http://hdl.handle.net/10212/2019
閲覧可能ファイル
ファイル
フォーマット
サイズ
閲覧回数
説明
INVEST1
pdf
10.9 MB
1,809
論文情報
title
INVESTIGATIONS ON THE FRACTURE BEHAVIOR AND NOTCH SENSITIVITY OF INJECTION MOLDINGS
contributor.author
BERNARD CHUKWUEMEKA OGAZI-ONYEMAECHI
subject
Skin-core structure
V-shaped notch
hairline crack
pseudo-skin
skin
interface
core
stress concentrators
notch sensitivity factor for energy
notch sensitivity factor for strength
annealing
toughness
crack-tip temperature
essential work of fracture
full ligament yielding
VPET, RPET
GFPP, maximum stress intensity factor
strain energy release rate
interfacial strength
カテゴリ
学位授与年月日:2010.09.24
論文詳細を表示
title
INVESTIGATIONS ON THE FRACTURE BEHAVIOR AND NOTCH SENSITIVITY OF INJECTION MOLDINGS
contributor.author
BERNARD CHUKWUEMEKA OGAZI-ONYEMAECHI
subject
Skin-core structure
V-shaped notch
hairline crack
pseudo-skin
skin
interface
core
stress concentrators
notch sensitivity factor for energy
notch sensitivity factor for strength
annealing
toughness
crack-tip temperature
essential work of fracture
full ligament yielding
VPET, RPET
GFPP, maximum stress intensity factor
strain energy release rate
interfacial strength
date.accessioned
2010-10-06T01:08:14Z
date.available
2010-10-06T01:08:14Z
date.issued
2010-09-24
description.abstract
The prevention of catastrophic failures in engineering components depends largely on the accurate prediction of their fracture mechanism. Much research efforts have been made to understand the fracture toughness of polymeric materials and composites but these are limited to investigations conducted on samples introduced with single-depth standard V-notches. However, there is inadequate understanding on the notch sensitivity of injection moldings especially when a hierarchical skin-core structure is present. Therefore, this thesis focused on characterizing the fracture toughness of injection molded polyethylene terephthalate (PET) and glass fiber reinforced polypropylene (GFPP) composites, both of which are known for being notch sensitive. Chapters 3 and 4 of this thesis were dedicated to understanding the effects of standard V-notch and sharper hairline cracks, respectively, on the fracture mechanism of neat- (V-PET) and recycled-PET (R-PET) injection moldings. The PET specimens exhibited very distinct skin-core structures and the depths of these regions were well defined. Upon tensile test, the specimens would remain semi-ductile as long as the V-notch depth was within the skin region. The skin region was tougher due to its lower crystallinity and would therefore, yield extensively during tensile loading. However, brittle fracture was imminent when the notch penetrated the skin into the core, which had higher crystallinity than the skin. Nevertheless, except upon annealing, the toughness of the skin region was compromised when sharper hairline cracks were introduced. The dependence of crack-tip temperature on stress intensity and notch sensitivity was investigated in Chapter 5. High crack-tip temperatures would indicate full ligament yielding, which provided the necessary requirements for the application of essential work of fracture principles in characterizing the fracture toughness of the specimens. Chapters 6 and 7 of the thesis were dedicated to investigating the effect of polypropylene (PP) molecular weight on the fracture toughness of glass fiber reinforced PP (GFPP) composites. Elastic plastic fracture mechanics have revealed that GFPP containing the lowest molecular weight PP (J-3000GP) exhibited the highest fracture toughness due to its high interfacial shear strength that resulted in more fiber breakage and better resistance to crack propagation.
description.provenance
Submitted by 附属図書館 KIT-Repository (dspace-admin@jim.kit.ac.jp) on 2010-10-06T01:08:14Z No. of bitstreams: 1 INVEST1.pdf: 11502738 bytes, checksum: 581757557f0ea4a07ebc92edeff29932 (MD5)
Made available in DSpace on 2010-10-06T01:08:14Z (GMT). No. of bitstreams: 1 INVEST1.pdf: 11502738 bytes, checksum: 581757557f0ea4a07ebc92edeff29932 (MD5) Previous issue date: 2010-09-24
description
所属:大学院工芸科学研究科博士後期課程先端ファイブロ科学専攻;取得大学:京都工芸繊維大学 ; 取得学位:博士(学術); 学位授与年月日:2010-09-24 ; 証書番号:博甲第583号
format.extent
11502738 bytes
format.mimetype
application/pdf
identifier.uri
http://hdl.handle.net/10212/2019
language.iso639-2
en
rights.textversion
author
type.nii
Thesis or Dissertation
type
Thesis