Investigating pressure magnitudes at depth for oblique impacts into layered targets: Applications to terrestrial impacts in sedimentary targets

Stickle, A. M.; Schultz, P. H.

doi:10.1111/maps.12152

Cited by 10 publications

(7 citation statements)

References 46 publications

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“…Previous studies focused on planar polymethylmethacrylate (PMMA) targets in order to track the evolution of subsurface damage following oblique impacts for both impacts directly into PMMA [Stickle and Schultz, 2011;Stickle and Schulz, 2014] and impacts into layered PMMA and geologic targets [Stickle and Schultz, 2012;Stickle and Schultz, 2013]. At planetary scales, however, target curvature creates shock-wave interactions that significantly change the damage pattern (and process).…”

Section: Methods and Approachmentioning

confidence: 99%

Peak Bone Mass and Quantitative Ultrasound Bone Properties in Young Adulthood: A Study in the PEAK-25 Cohort of Women

Sandström

McGuigan

Callréus

et al. 2016

Journal of Clinical Densitometry

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Peak bone mass is normally reached in the third decade of life. Previously, in the population-based PEAK-25 cohort (n = 1061, age 25.5 ± 0.2), we demonstrated that bone mineral density in the population-based PEAK-25 cohort is comparatively high; therefore, this study aimed to determine if the calcaneus microarchitecture mirrored this. In the process, we describe normative quantitative ultrasound (QUS) values for 25-yr-old women and the relationship between QUS values and extremes of body weight. QUS variables speed of sound (SOS), broadband ultrasound attenuation (BUA), and stiffness index were measured. Young adult values were based on the manufacturer-supplied QUS reference values. Analyses were performed in the cohort as a whole, and additionally, to understand the relationship between body weight and QUS values in young women, the variables were categorized into octiles for weight or body mass index (BMI) and the lowest and highest octiles were compared. In the cohort, SOS values, reflecting bone density, were higher (108 ± 18%), whereas BUA values, reflecting bone complexity, were lower (90 ± 14%) compared to the young adult reference population. SOS did not correlate with body weight or BMI. In the cohort, overall correlations between BUA weight, and BMI were small and positive (Pearson's r coefficients 0.261 and 0.197, respectively; p < 0.001), although in the low-weight group, r coefficients were higher (r = 0.313 and 0.268; p < 0.05). In contrast, in the high-weight group, correlation with BUA values tended to be small, negative, and nonsignificant. Correlation between QUS and dual-energy X-ray absorptiometry-measured bone mineral density was low to moderate and significant at all skeletal sites (r = 0.37-0.52). Whereas coefficients tended to be higher in the low-weight group, the reverse was apparent for the low-BMI group. In these 25-yr-old women, a comparatively high dual-energy X-ray absorptiometry-measured bone mass is offset by less complex bone structures assessed by QUS. This may have implications for later osteoporosis assessment and future fracture risk.

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Section: Methods and Approachmentioning

confidence: 99%

Peak Bone Mass and Quantitative Ultrasound Bone Properties in Young Adulthood: A Study in the PEAK-25 Cohort of Women

Sandström

McGuigan

Callréus

et al. 2016

Journal of Clinical Densitometry

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“…Shear‐induced damage is examined using the Johnson‐Cook Fracture (JCF) model [ Johnson and Cook , ]. The JCF is a scalar damage model and is used to illustrate regions failing due to high deviatoric stress components within the PMMA target (this same procedure was used in, e.g., Stickle and Schultz [, , ]). In general, this failure criterion is dependent on plastic strain to fracture as a function of equivalent plastic strain, pressure, temperature, strain rate, and loading path (a more detailed description of this model can be found in Stickle and Schultz []).…”

Section: Methodsmentioning

confidence: 99%

Discrete shear failure planes resulting from oblique hypervelocity impacts

Stickle

Schultz

2014

J. Geophys. Res. Planets

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A combination of laboratory and numerical experiments examines the role of shear localization in subsurface damage following very oblique (15-30°) hypervelocity impacts. Laboratory experiments reveal subsurface damage planes ("blades") parallel to the impact trajectory for highly oblique impacts (15-30°), which are characterized by unique surface textures relative to other failure regions. Observations of growth rate and surface texture of the damage planes combined with three-dimensional CTH simulations indicate that the blades are the result of frictional processes during localized shear deformation. Laboratory experiments also reveal that impact angle and projectile failure play a role in the development of these blades: aluminum projectiles result in distinct along-trajectory blades for both 15°and 30°impacts, whereas the blades are weakly developed for Pyrex projectiles and nonexistent for planar polymethylmethacrylate projectiles. The blades form early in the cratering process and are signatures of the projectile momentum being transferred into the target. Based on the growth rate, and melting seen along the surface of these damage planes, the blades may provide an analog for the generation of pseudotachylytes during the early stages of impact crater formation.

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“…Many studies of impact craters have discussed variations in morphology as dependence on the underlying layered material. Stickle and Schultz () discussed the lack of distinctive shock features at the Rock Elm impact structure (Wisconsin) as a result of low‐impedance surface layers over high‐impedance bedrock, which affects the shock effects in the substrate. This was confirmed by laboratory and computational modeling showing how a nonhomogenous target produces distinct crater morphology (Stickle and Schultz ).…”

Section: Introductionmentioning

confidence: 99%

“…Stickle and Schultz () discussed the lack of distinctive shock features at the Rock Elm impact structure (Wisconsin) as a result of low‐impedance surface layers over high‐impedance bedrock, which affects the shock effects in the substrate. This was confirmed by laboratory and computational modeling showing how a nonhomogenous target produces distinct crater morphology (Stickle and Schultz ). Impacts into a layered target with variation in material strength between sedimentary and crystalline layers were undertaken by Collins and Wünnemann (), investigating the formation of the Chesapeake Bay impact, who found that the distinctive features of this impact crater are due to the layered target properties.…”

Section: Introductionmentioning

confidence: 99%

Hypervelocity impacts into ice‐topped layered targets: Investigating the effects of ice crust thickness and subsurface density on crater morphology

Harriss

Burchell

2017

Meteorit & Planetary Scien

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Abstract-Many bodies in the outer solar system are theorized to have an ice shell with a different subsurface material below, be it chondritic, regolith, or a subsurface ocean. This layering can have a significant influence on the morphology of impact craters. Accordingly, we have undertaken laboratory hypervelocity impact experiments on a range of multilayered targets, with interiors of water, sand, and basalt. Impact experiments were undertaken using impact speeds in the range of 0.8-5.3 km s À1, a 1.5 mm Al ball bearing projectile, and an impact incidence of 45°. The surface ice crust had a thickness between 5 and 50 mm, i.e., some 3-30 times the projectile diameter. The thickness of the ice crust as well as the nature of the subsurface layer (liquid, well consolidated, etc.) have a marked effect on the morphology of the resulting impact crater, with thicker ice producing a larger crater diameter (at a given impact velocity), and the crater diameter scaling with impact speed to the power 0.72 for semi-infinite ice, but with 0.37 for thin ice. The density of the subsurface material changes the structure of the crater, with flat crater floors if there is a dense, well-consolidated subsurface layer (basalt) or steep, narrow craters if there is a less cohesive subsurface (sand). The associated faulting in the ice surface is also dependent on ice thickness and the substrate material. We find that the ice layer (in impacts at 5 km s À1 ) is effectively semi-infinite if its thickness is more than 15.5 times the projectile diameter. Below this, the crater diameter is reduced by 4% for each reduction in ice layer thickness equal to the impactor diameter. Crater depth is also affected. In the ice thickness region, 7-15.5 times the projectile diameter, the crater shape in the ice is modified even when the subsurface layer is not penetrated. For ice thicknesses, <7 times the projectile diameter, the ice layer is breached, but the nature of the resulting crater depends heavily on the subsurface material. If the subsurface is noncohesive (loose) material, a crater forms in it. If it is dense, well-consolidated basalt, no crater forms in the exposed subsurface layer.

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Investigating pressure magnitudes at depth for oblique impacts into layered targets: Applications to terrestrial impacts in sedimentary targets

Cited by 10 publications

References 46 publications

Peak Bone Mass and Quantitative Ultrasound Bone Properties in Young Adulthood: A Study in the PEAK-25 Cohort of Women

Peak Bone Mass and Quantitative Ultrasound Bone Properties in Young Adulthood: A Study in the PEAK-25 Cohort of Women

Discrete shear failure planes resulting from oblique hypervelocity impacts

Hypervelocity impacts into ice‐topped layered targets: Investigating the effects of ice crust thickness and subsurface density on crater morphology

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