{"title":"裂缝前局部纤维分布对FRP断裂韧性的影响","authors":"T. Kunio, M. Shimizu, S. Sohmiya","doi":"10.1016/0015-0568(83)90011-8","DOIUrl":null,"url":null,"abstract":"<div><p>A study has been made of the effect of a local fibre distribution in the vicinity of a crack on the fracture toughness G<sub>c</sub> of glass fibre reinforced epoxy resins, which have ten kinds of fibre volume fraction including very low fraction, by means of fracture mechanics and fractography.</p><p>The results obtained are summarized as follows: </p><ul><li><span>1.</span><span><p>(1) There exists a critical fibre volume fraction V<sub>fc</sub>; below V<sub>fc</sub>, the strengthening effect due to fibre does not affect the fracture toughness of the material. The fracture toughness of the FRP having V<sub>f</sub> larger than V<sub>fc</sub> increases linearly with V<sub>f</sub> on the log-log diagram.</p></span></li><li><span>2.</span><span><p>(2) A phenomenon of local pop-in at a pre-crack front precedes a global advancement of a crack front. The local pop-in occurs preferentially at some particular locations along the pre-crack front where the fibre spacing is locally wide.</p></span></li><li><span>3.</span><span><p>(3) The fracture toughness of FRP depends not only on the macroscopic fibre volume fraction V<sub>f</sub> in the material but also on the local volume fraction V<sub>fL</sub> and on the local fibre spacing D<sub>ave</sub> in the vicinity of the pre-crack front. Both increase of the V<sub>fL</sub> and decrease of the D<sub>ave</sub> have the same effect of increasing the fracture toughness of FRP.</p></span></li><li><span>4.</span><span><p>(4) The scatter of fracture toughness values in a conventional fracture toughness test can be well explained by considering the effect of V<sub>fL</sub> and D<sub>ave</sub> upon the fracture toughness.</p></span></li></ul></div>","PeriodicalId":100525,"journal":{"name":"Fibre Science and Technology","volume":"18 2","pages":"Pages 151-162"},"PeriodicalIF":0.0000,"publicationDate":"1983-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0015-0568(83)90011-8","citationCount":"6","resultStr":"{\"title\":\"Effect of local fibre distribution ahead of crack on the fracture toughness of FRP\",\"authors\":\"T. Kunio, M. Shimizu, S. Sohmiya\",\"doi\":\"10.1016/0015-0568(83)90011-8\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>A study has been made of the effect of a local fibre distribution in the vicinity of a crack on the fracture toughness G<sub>c</sub> of glass fibre reinforced epoxy resins, which have ten kinds of fibre volume fraction including very low fraction, by means of fracture mechanics and fractography.</p><p>The results obtained are summarized as follows: </p><ul><li><span>1.</span><span><p>(1) There exists a critical fibre volume fraction V<sub>fc</sub>; below V<sub>fc</sub>, the strengthening effect due to fibre does not affect the fracture toughness of the material. The fracture toughness of the FRP having V<sub>f</sub> larger than V<sub>fc</sub> increases linearly with V<sub>f</sub> on the log-log diagram.</p></span></li><li><span>2.</span><span><p>(2) A phenomenon of local pop-in at a pre-crack front precedes a global advancement of a crack front. The local pop-in occurs preferentially at some particular locations along the pre-crack front where the fibre spacing is locally wide.</p></span></li><li><span>3.</span><span><p>(3) The fracture toughness of FRP depends not only on the macroscopic fibre volume fraction V<sub>f</sub> in the material but also on the local volume fraction V<sub>fL</sub> and on the local fibre spacing D<sub>ave</sub> in the vicinity of the pre-crack front. Both increase of the V<sub>fL</sub> and decrease of the D<sub>ave</sub> have the same effect of increasing the fracture toughness of FRP.</p></span></li><li><span>4.</span><span><p>(4) The scatter of fracture toughness values in a conventional fracture toughness test can be well explained by considering the effect of V<sub>fL</sub> and D<sub>ave</sub> upon the fracture toughness.</p></span></li></ul></div>\",\"PeriodicalId\":100525,\"journal\":{\"name\":\"Fibre Science and Technology\",\"volume\":\"18 2\",\"pages\":\"Pages 151-162\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"1983-02-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1016/0015-0568(83)90011-8\",\"citationCount\":\"6\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Fibre Science and Technology\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/0015056883900118\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Fibre Science and Technology","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/0015056883900118","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Effect of local fibre distribution ahead of crack on the fracture toughness of FRP
A study has been made of the effect of a local fibre distribution in the vicinity of a crack on the fracture toughness Gc of glass fibre reinforced epoxy resins, which have ten kinds of fibre volume fraction including very low fraction, by means of fracture mechanics and fractography.
The results obtained are summarized as follows:
1.
(1) There exists a critical fibre volume fraction Vfc; below Vfc, the strengthening effect due to fibre does not affect the fracture toughness of the material. The fracture toughness of the FRP having Vf larger than Vfc increases linearly with Vf on the log-log diagram.
2.
(2) A phenomenon of local pop-in at a pre-crack front precedes a global advancement of a crack front. The local pop-in occurs preferentially at some particular locations along the pre-crack front where the fibre spacing is locally wide.
3.
(3) The fracture toughness of FRP depends not only on the macroscopic fibre volume fraction Vf in the material but also on the local volume fraction VfL and on the local fibre spacing Dave in the vicinity of the pre-crack front. Both increase of the VfL and decrease of the Dave have the same effect of increasing the fracture toughness of FRP.
4.
(4) The scatter of fracture toughness values in a conventional fracture toughness test can be well explained by considering the effect of VfL and Dave upon the fracture toughness.
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