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Fracture mechanics by three-dimensional crack-tip synchrotron X-ray microscopy.

Withers PJ - Philos Trans A Math Phys Eng Sci (2015)

Bottom Line: X-ray diffraction provides information about the crack-tip stress field, phase transformations, plastic zone and crack-face tractions and forces.Time-lapse CT, besides providing information about the three-dimensional nature of the crack and its local growth rate, can also provide information as to the activation of extrinsic toughening mechanisms such as crack deflection, crack-tip zone shielding, crack bridging and crack closure.It is shown how crack-tip microscopy allows a quantitative measure of the crack-tip driving force via the stress intensity factor or the crack-tip opening displacement.

View Article: PubMed Central - PubMed

Affiliation: Manchester X-ray Imaging Facility, School of Materials, Manchester University, Manchester M13 9PL, UK Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0FA, UK p.j.withers@manchester.ac.uk.

ABSTRACT
To better understand the relationship between the nucleation and growth of defects and the local stresses and phase changes that cause them, we need both imaging and stress mapping. Here, we explore how this can be achieved by bringing together synchrotron X-ray diffraction and tomographic imaging. Conventionally, these are undertaken on separate synchrotron beamlines; however, instruments capable of both imaging and diffraction are beginning to emerge, such as ID15 at the European Synchrotron Radiation Facility and JEEP at the Diamond Light Source. This review explores the concept of three-dimensional crack-tip X-ray microscopy, bringing them together to probe the crack-tip behaviour under realistic environmental and loading conditions and to extract quantitative fracture mechanics information about the local crack-tip environment. X-ray diffraction provides information about the crack-tip stress field, phase transformations, plastic zone and crack-face tractions and forces. Time-lapse CT, besides providing information about the three-dimensional nature of the crack and its local growth rate, can also provide information as to the activation of extrinsic toughening mechanisms such as crack deflection, crack-tip zone shielding, crack bridging and crack closure. It is shown how crack-tip microscopy allows a quantitative measure of the crack-tip driving force via the stress intensity factor or the crack-tip opening displacement. Finally, further opportunities for synchrotron X-ray microscopy are explored.

No MeSH data available.


Related in: MedlinePlus

Schematic illustrating the wide range of qualitative and quantitative fracture mechanics information that can be obtained by (a) diffraction and (b) imaging [11]. Of course, not all the shielding mechanisms shown here are likely to be available in any particular case. (Online version in colour.)
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RSTA20130157F1: Schematic illustrating the wide range of qualitative and quantitative fracture mechanics information that can be obtained by (a) diffraction and (b) imaging [11]. Of course, not all the shielding mechanisms shown here are likely to be available in any particular case. (Online version in colour.)

Mentions: To progress, we need a means of extracting quantitative information about the local crack-tip environment. Emerging techniques such as digital image correlation allow the crack-tip deformation field to be probed at the surface, but many cracks are either inherently three dimensional or initiate in the interior. This review describes the concept of three-dimensional X-ray microscopy, combining diffraction and imaging modes as in a transmission electron microscope to probe the conditions at the crack tip (figure 1). Instruments capable of this are beginning to emerge, such as ID15 at the European Synchrotron Radiation Facility (ESRF) and JEEP at the Diamond Light Source. This review explores the types of information that can be provided by diffraction (figure 1a) and by CT imaging (figure 1b). For reasons of space, many practical aspects associated with residual stress mapping by diffraction and imaging by computer tomography are not covered in this paper, but excellent introductions to both techniques are available; for example, [12] and [13,14] for diffraction and imaging, respectively.Figure 1.


Fracture mechanics by three-dimensional crack-tip synchrotron X-ray microscopy.

Withers PJ - Philos Trans A Math Phys Eng Sci (2015)

Schematic illustrating the wide range of qualitative and quantitative fracture mechanics information that can be obtained by (a) diffraction and (b) imaging [11]. Of course, not all the shielding mechanisms shown here are likely to be available in any particular case. (Online version in colour.)
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4308984&req=5

RSTA20130157F1: Schematic illustrating the wide range of qualitative and quantitative fracture mechanics information that can be obtained by (a) diffraction and (b) imaging [11]. Of course, not all the shielding mechanisms shown here are likely to be available in any particular case. (Online version in colour.)
Mentions: To progress, we need a means of extracting quantitative information about the local crack-tip environment. Emerging techniques such as digital image correlation allow the crack-tip deformation field to be probed at the surface, but many cracks are either inherently three dimensional or initiate in the interior. This review describes the concept of three-dimensional X-ray microscopy, combining diffraction and imaging modes as in a transmission electron microscope to probe the conditions at the crack tip (figure 1). Instruments capable of this are beginning to emerge, such as ID15 at the European Synchrotron Radiation Facility (ESRF) and JEEP at the Diamond Light Source. This review explores the types of information that can be provided by diffraction (figure 1a) and by CT imaging (figure 1b). For reasons of space, many practical aspects associated with residual stress mapping by diffraction and imaging by computer tomography are not covered in this paper, but excellent introductions to both techniques are available; for example, [12] and [13,14] for diffraction and imaging, respectively.Figure 1.

Bottom Line: X-ray diffraction provides information about the crack-tip stress field, phase transformations, plastic zone and crack-face tractions and forces.Time-lapse CT, besides providing information about the three-dimensional nature of the crack and its local growth rate, can also provide information as to the activation of extrinsic toughening mechanisms such as crack deflection, crack-tip zone shielding, crack bridging and crack closure.It is shown how crack-tip microscopy allows a quantitative measure of the crack-tip driving force via the stress intensity factor or the crack-tip opening displacement.

View Article: PubMed Central - PubMed

Affiliation: Manchester X-ray Imaging Facility, School of Materials, Manchester University, Manchester M13 9PL, UK Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0FA, UK p.j.withers@manchester.ac.uk.

ABSTRACT
To better understand the relationship between the nucleation and growth of defects and the local stresses and phase changes that cause them, we need both imaging and stress mapping. Here, we explore how this can be achieved by bringing together synchrotron X-ray diffraction and tomographic imaging. Conventionally, these are undertaken on separate synchrotron beamlines; however, instruments capable of both imaging and diffraction are beginning to emerge, such as ID15 at the European Synchrotron Radiation Facility and JEEP at the Diamond Light Source. This review explores the concept of three-dimensional crack-tip X-ray microscopy, bringing them together to probe the crack-tip behaviour under realistic environmental and loading conditions and to extract quantitative fracture mechanics information about the local crack-tip environment. X-ray diffraction provides information about the crack-tip stress field, phase transformations, plastic zone and crack-face tractions and forces. Time-lapse CT, besides providing information about the three-dimensional nature of the crack and its local growth rate, can also provide information as to the activation of extrinsic toughening mechanisms such as crack deflection, crack-tip zone shielding, crack bridging and crack closure. It is shown how crack-tip microscopy allows a quantitative measure of the crack-tip driving force via the stress intensity factor or the crack-tip opening displacement. Finally, further opportunities for synchrotron X-ray microscopy are explored.

No MeSH data available.


Related in: MedlinePlus