Can water cause brittle fracture failures of composite non-ceramic insulators in the absence of electric fields?

M. Kumosa, L. Kumosa, D. Armentrout

Research output: Contribution to journalArticlepeer-review


It was postulated in [1], based on experimental evidence, that brittle fracture failures of composite (non-ceramic) HV insulators could be caused by water and mechanical stresses. It was also claimed therein that the brittle fracture process was more likely to happen with water than acids. This postulation could be of major importance as its ramifications might affect the entire composite insulator technology and, in particular, the usage of glass fiber polymer matrix composites in HV applications. Such an important statement should not be left without an independent verification. Therefore, attempts have been made in this research to initiate this process in unidirectional E-glass/modified polyester and E-glass/vinyl ester composites, used in non-ceramic insulators, by subjecting them to water under four-point bending conditions. This was done to independently verify the main conclusion of [1] that water may be more damaging to unidirectional E-glass/polymer composites than acids. It has been clearly shown in this work that water, in the absence of electrical field, cannot cause stress corrosion cracking of unidirectional E-glass/polymer composites and thus brittle fracture of composite non-ceramic insulators. Thus the main results of [1] could not be independently reproduced.

Original languageEnglish
Pages (from-to)523-533
JournalIEEE Transactions on Dielectrics and Electrical Insulation
Issue number3
Publication statusPublished - 2004 Jun
Externally publishedYes

Free keywords

  • Brittle fracture
  • Composite polymers
  • Fiberglass
  • Glass fiber
  • High voltage insulators
  • Non-ceramic insulators
  • Stress corrosion cracking


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