Measurement of lateral compressive stresses under shock loading

“…see for example the works of Gupta et al, 7,8 and Rosenberg and Partom. 9 The advantage of this method is that now shear strength is deduced from two measured values.…”

Section: Introductionmentioning

confidence: 99%

The deviatoric response of polymethylmethacrylate to one-dimensional shock loading

Millett¹,

Bourne²

2000

“…Because material strength determination is important for understanding and predicting the response of solids to dynamic loading, several methods for real time strength determination have been used over the past several decades. 1 These include particle velocity unloading and reloading results, 1-5 piezoresistance stress gauge measurements, [6][7][8][9] and compression-shear loading. 10,11 All of the aforementioned methods probe the sample on the continuum scale, and each method entails certain assumptions.…”

Section: Introductionmentioning

confidence: 99%

Real time synchrotron x-ray diffraction measurements to determine material strength of shocked single crystals following compression and release

Turneaure

Gupta

2009

Self Cite

We present a method to use real time, synchrotron x-ray diffraction measurements to determine the strength of shocked single crystals following compression and release during uniaxial strain loading. Aluminum and copper single crystals shocked along [111] were examined to peak stresses ranging from 2 to 6 GPa. Synchrotron x rays were used to probe the longitudinal lattice strains near the rear free surface (16 and 5 μm depths for Al and Cu, respectively) of the metal crystals following shock compression and release. The 111 diffraction peaks showed broadening indicating a heterogeneous microstructure in the released state. The diffraction peaks also shifted to lower Bragg angles relative to the ambient Bragg angle; the magnitude of the shift increased with increasing impact stress. The Bragg angle shifts and appropriate averaging procedures were used to determine the macroscopic or continuum strength following compression and release. For both crystals, the strengths upon release increased with increasing impact stress and provide a quantitative measure of the strain hardening that occurs in Al(111) and Cu(111) during the shock and release process. Our results for Al(111) are in reasonable agreement with a previous determination based solely on continuum measurements. Two points are noteworthy about the developments presented here: Synchrotron x rays are needed because they provide the resolution required for analyzing the data in the released state; the method presented here can be extended to the shocked state but will require additional measurements.

“…[13][14][15] This places the gauge within material flow, and hence not only can shear strength be measured, but with a gauge of suitable geometry, changes in shear strength behind the shock front can be shown. Lateral stress can be monitored by sectioning the sample in half and introducing a stress gauge before reassembling.…”

Section: Introductionmentioning

confidence: 99%

The role of aging on the mechanical and microstructural response of aluminum 6061 to one-dimensional shock loading

Millett¹,

Bourne²,

Chu³

et al. 2010

Articles you may be interested inLateral stress and shear strength behind the shock front in three face centered cubic metals J. Appl. Phys. 105, 033515 (2009); 10.1063/1.3077206 The response of the intermetallic compound Ni 3 Al to one-dimensional shock loading Compressive strength measurements in aluminum for shock compression over the stress range of 4 -22 GPa J. Appl. Phys. 98, 033524 (2005); 10.1063/1.2001729 Shock induced mechanical response of a γ-TiAl alloyThe shock response of the aluminum alloy 6061, and its variation according to heat treatment have been monitored via the placement of stress gauges in such orientations so as to be sensitive to the lateral component of stress, and hence the shear strength. To complement these measurements, the postshock microstructure and mechanical response have also been determined via full one-dimensional recovery techniques. Results have shown that the solution treated ͑T0͒ state, as a largely single phase material displays a fast rising shock pulse with a significant degree of hardening behind the shock front. This indicates that a high degree of dislocation generation is expected. Postshock analysis of recovered samples has confirmed this hypothesis, with dislocation cells being observed and a notable increase in the yield strength in comparison to the as-received material. In contrast, the aged ͑T6͒ experiments showed a much longer rise time with a lower degree of hardening behind the shock front. Microstructural analysis postshock shows a more randomized dislocation distribution, with little or no postshock hardening occurring once the shock induced strain has been accounted for. This has been attributed to the presence of fine Mg 2 Si precipitates inhibiting the motion and generation of dislocations. These measurements are in agreement with work previously carried out on this material. Comparison of the shear strengths of the two heat treatments also shows that although the T6 condition is a little higher than T0, the differences are somewhat lower than expected.