Normas ASTM Tribologia e Microdureza
Transcript of Normas ASTM Tribologia e Microdureza
Carlos V. Opelt, Geraldo M. Cândido and Mirabel C. Rezende
COMPRESSION FAILURE MODES OF CARBON FIBER FABRIC SCRAPS - EPOXY LAMINATES
Technological Institute of Aeronautics
São José dos Campos - Brazil
Federal University of São Paulo
São José dos Campos - Brazil
• Introduction
• Goals
• Failure modes
• Case studies
• Application to design of composites
• Conclusions
SUMMARY
• Introduction
• Goals
• Failure modes
• Case studies
• Application to design of composites
• Conclusions
SUMMARY
• Few decades ago, the fiber reinforced polymer composites were considered the panacea of the materials for structural application.
• Over the years researchers have demonstrated that these materials are strongly affected by manufacturing defects and operation damages.
• The proper use of polymer composites requires the knowledge of their mechanical response under different loadings, as well as their failure mechanisms.
03 INTRODUCTION
• The compression behavior is a limiting in the design of structures made of carbon fiber reinforced polymers.
• The compressive strength of unidirectional carbon fiber/epoxy laminates is often less than 60% of their tensile strength.
• This relatively low compressive strength of polymer composites, compared to its tensile strength, is due to matrix properties governing the compressive failure.
04 INTRODUCTION
• The fiber-reinforced composites subjected to compressive loads can exhibit different failure modes with a different sequence of events to the fracture.
• There is a lack of consensus on the description and classification of the compressive failure modes that makes its assessment unfeasible.
• In some cases different authors end up describing the failure differently, despite the fracture aspects being very similar.
05 INTRODUCTION
• One example of classification is the one by ASTM standards (D3410M-03 e D6641-09).
06 INTRODUCTION
• Introduction
• Goals
• Failure modes
• Case studies
• Application to design of composites
• Conclusions
SUMMARY
• Propose a classification that considers the failure modes already described in the literature and that can easily include new cases being reported.
• To present case studies that demonstrate how to apply this classification.
• Explore how the knowledge of the failure modes can help in the analysis and design of composite structures.
07 GOALS
• Introduction
• Goals
• Failure modes
• Case studies
• Application to design of composites
• Conclusions
SUMMARY
• The proposed classification was based on the failure modes already reported in the literature, trying to cluster the ones with similar characteristics.
08 FAILURE MODES
• The proposed classification was based on the failure modes already reported in the literature, trying to cluster the ones with similar characteristics.
08 FAILURE MODES
In-plane Shear Through-the-thickness
Shear Wedge Splitting
09 SHEAR FAILURES
In-plane Shear
09 SHEAR FAILURES
Propagation in the width direction
Angled propagation
Through-the-thickness Shear
09 SHEAR FAILURES
Propagation in the thickness direction
Angled propagation
Flexural damages due to the sliding
surfaces
Wedge Splitting
09 SHEAR FAILURES
Two cracks propagating in the thickness direction
Formation of a wedge
Propagation of a large delamination
• The proposed classification was based on the failure modes already reported in the literature, trying to cluster the ones with similar characteristics.
08 FAILURE MODES
10 INTERLAMINAR FAILURES
Delamination Buckling Splitting
10 INTERLAMINAR FAILURES
Delamination Buckling
Buckling of the layers
Multiple delaminations
Splaying of the layers
10 INTERLAMINAR FAILURES
Splitting
Crushing of the layers
Multiple delaminations
• The proposed classification was based on the failure modes already reported in the literature, trying to cluster the ones with similar characteristics.
08 FAILURE MODES
11 INTERFACIAL FAILURES
Brooming Fiber Crushing
11 INTERFACIAL FAILURES
Brooming
Buckling of the fibers
Broom-like fracture
Extensive propagation of the interfacial cracks
11 INTERFACIAL FAILURES
Fiber Crushing
Restricted propagation of the interfacial cracks
Fibers are crushed against each other
• The proposed classification was based on the failure modes already reported in the literature, trying to cluster the ones with similar characteristics.
08 FAILURE MODES
12 KINK-BAND FAILURES
In-plane Kink-band Through-the-thickness
Shear
12 KINK-BAND FAILURES
In-plane Kink-band Propagation in the
width direction
Propagation of an angled band
The interfacial cracks are restricted to the band
12 KINK-BAND FAILURES
Through-the-thickness Shear
Propagation in the thickness direction
Propagation of an angled band
The interfacial cracks are restricted to the band
13 IRREGULAR PROPAGATION
Multiple Failure Modes Mixed Failure Modes
13 IRREGULAR PROPAGATION
Multiple Failure Modes
Irregular propagation in the width direction
Different failure modes in the two sides of the specimen
13 IRREGULAR PROPAGATION
Mixed Failure Modes
Irregular propagation in the width direction
Different failure modes in the two sides of the specimen
14 GLOBAL AND LOCAL MODES
Global Failure Mode Local Failure Mode
14 GLOBAL AND LOCAL MODES
Global Failure Mode Local Failure Mode
Fiber Crushing Failure
Wedge Splitting Failure
• Introduction
• Goals
• Failure modes
• Case studies
• Application to design of composites
• Conclusions
SUMMARY
• J.M.F. Paiva; S. Mayer; M.C. Rezende "Evaluation of mechanical properties of four different carbon/epoxy composites used in aeronautical field" Materials Research (2005, vol. 8, p. 91).
• Carbon fibers arranged as a plain weave fabric.
• Prepreg (epoxy matrix) - HexPly® F155, Hexcel Composites
15 FABRIC LAMINATE
16 FABRIC LAMINATE
16 FABRIC LAMINATE
Angled propagation
Shear Failure
16 FABRIC LAMINATE
Debris from the sliding of the fracture surfaces
Shear Failure
17 FABRIC LAMINATE
17 FABRIC LAMINATE
Irregular propagation in the thickness direction
Mixed Failure Mode Shear Failure
+ Delamination Buckling
17 FABRIC LAMINATE
Angled propagation
Mixed Failure Mode Shear Failure
+ Delamination Buckling
17 FABRIC LAMINATE
Multiple delaminations
Mixed Failure Mode Shear Failure
+ Delamination Buckling
17 FABRIC LAMINATE
Splaying of the layers
Mixed Failure Mode Shear Failure
+ Delamination Buckling
18 FABRIC LAMINATE
18 FABRIC LAMINATE
Multiple Failure Modes Shear Failure Mode
+ Mixed Failure Modes
19 FABRIC LAMINATE
Local Failure Mode
19 FABRIC LAMINATE
Kink-band Failure
• C.V. Opelt; C.S.R. Souza; J.M.F. Marlet; G.M. Cândido; M.C. Rezende "Compression Failure Modes of Carbon Fiber Fabric Scraps/Epoxy Laminates" 20th International Conference on Composite Materials.
• Prepreg scraps plain weave fabric (HexPly® F155) were positioned side-by-side with a random orientatiom.
20 FABRIC SCRAPS LAMINATE
21 FABRIC SCRAPS LAMINATE
21 FABRIC SCRAPS LAMINATE
Delamination
Wedge
Wedge
Delamination
21 FABRIC SCRAPS LAMINATE
Flexural damages
Flexural damages
22 FABRIC SCRAPS LAMINATE
22 FABRIC SCRAPS LAMINATE
Multiple delaminations
Multiple delaminations
22 FABRIC SCRAPS LAMINATE
Buckling of the layers
Buckling of the layers
23 FABRIC SCRAPS LAMINATE
23 FABRIC SCRAPS LAMINATE
Irregular propagation
Irregular propagation
23 FABRIC SCRAPS LAMINATE
Multiple delaminations
Multiple delaminations
23 FABRIC SCRAPS LAMINATE
Buckling of the layers
Buckling of the layers
23 FABRIC SCRAPS LAMINATE
Delamination
Wedge
Wedge
Delamination
23 FABRIC SCRAPS LAMINATE
Flexural damages
Flexural damages
• Introduction
• Goals
• Failure modes
• Case studies
• Application to design of composites
• Conclusions
SUMMARY
• The analysis of the compression failure modes is not straightforward and requires some time and effort to be made.
• This kind of information can aid the designers to control the compressive behavior of composite structures.
• The literature presents evidence that for each failure mode a compressive strength distribution can be found.
24 APLICATION TO DESIGN
• The paper of Odom and Adams (1990) shows some interesting findings:
• The through the thickness shear failures are related with the minimum possible compressive strength.
• The maximum possible compressive strength can be expected to be associated with the in plane shear failure.
25 APLICATION TO DESIGN
• Among this two boundaries lay the other possible failure modes.
Narayanan and Schadler (1999)
Lankford (1995)
26 APLICATION TO DESIGN
Compressive strength
27 APLICATION TO DESIGN
Unidirectional composites (ISS)
Compressive strength
27 APLICATION TO DESIGN
Unidirectional composites (ISS)
Compressive strength
27 APLICATION TO DESIGN
Unidirectional composites (ISS)
Compressive strength
27 APLICATION TO DESIGN
Unidirectional composites (ISS)
Compressive strength
27 APLICATION TO DESIGN
Fabric composites (ILSS)
Unidirectional composites (ISS)
Compressive strength
27 APLICATION TO DESIGN
Fabric composites (ILSS)
Unidirectional composites (ISS)
Compressive strength
27 APLICATION TO DESIGN
• To improve the performance of composites in compression, the failure modes associated with low compressive strengths should be avoided.
• Tougher and stiffer matrices, would lead to the splitting/fiber crushing failures (depending on the fiber arrangement) or even to in plane shear failures
28 APLICATION TO DESIGN
• Introduction
• Goals
• Failure modes
• Case studies
• Application to design of composites
• Conclusions
SUMMARY
• It was possible to group the compression failure modes accordingly to the properties that govern the fracture phenomenon.
• Two case studies were presented to demonstrate how to apply the proposed classification.
• The compressive strength behavior was found for each failure mode.
29 CONCLUSIONS
Thanks for the attention!