scholarly journals Fracture of Thin-Walled Polyoxymethylene Bulk Specimens in Modes I and III

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5096
Author(s):  
Peer Schrader ◽  
Anja Gosch ◽  
Michael Berer ◽  
Stephan Marzi
Keyword(s):  
Fracture Surface ◽  
Crack Growth ◽  
Cantilever Beam ◽  
Double Cantilever Beam ◽  
Polymeric Materials ◽  
Local Mode ◽  
Mode I ◽  
Mode Iii ◽  
Thin Walled ◽  
Twisting Angle

Thin-walled polymeric components are used in many applications. Hence, knowledge about their fracture behavior in bulk is beneficial in practice. Within this study, the double cantilever beam (DCB) and out-of-plane double cantilever beam (ODCB) tests are enhanced to enable the testing of such bulk specimens in mode I and mode III on the basis of the J-integral. This paper then presents and discusses the experimental results following the investigation of a semicrystalline polymer (polyoxymethylen) under quasi-static load conditions. From the experiments, fracture energies of similar magnitude in both mode I and mode III were determined. In mode III, pop-in fracture was observed. Furthermore, the fracture surfaces were investigated regarding the mode I and mode III dominant crack growth mechanisms, based on the morphology of the tested material. For specimens tested in mode I, no signs of plastic deformation were observed, and the fracture surface appears flat. In mode III, some samples display a twisted fracture surface (twisting angle close to 45°), which indicates local mode I crack growth. A transfer of the presented methodology to other (more ductile) polymeric materials is deemed possible without further restrictions. In addition, the presented setup potentially enables an investigation of polymeric bulk specimens in mixed mode I+III.

Double Cantilever Beam Measurement and Finite Element Analysis of Cryogenic Mode I Interlaminar Fracture Toughness of Glass-Cloth/Epoxy Laminates

2000 ◽  
Vol 123 (2) ◽  
pp. 191-197 ◽  
Author(s):  
Y. Shindo ◽  
K. Horiguchi ◽  
R. Wang ◽  
H. Kudo
Keyword(s):  
Fracture Toughness ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Cantilever Beam ◽  
Double Cantilever Beam ◽  
Mode I ◽  
Interlaminar Fracture Toughness ◽  
Element Analysis ◽  
Interlaminar Fracture ◽  
Delamination Crack

An experimental and analytical investigation in cryogenic Mode I interlaminar fracture behavior and toughness of SL-E woven glass-epoxy laminates was conducted. Double cantilever beam (DCB) tests were performed at room temperature (R.T.), liquid nitrogen temperature (77 K), and liquid helium temperature (4 K) to evaluate the effect of temperature and geometrical variations on the interlaminar fracture toughness. The fracture surfaces were examined by scanning electron microscopy to verify the fracture mechanisms. A finite element model was used to perform the delamination crack analysis. Critical load levels and the geometric and material properties of the test specimens were input data for the analysis which evaluated the Mode I energy release rate at the onset of delamination crack propagation. The results of the finite element analysis are utilized to supplement the experimental data.

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