A filament-level analysis on failure mechanism and ballistic limit of real-size multi-layer 2D woven fabrics under FSP impact

This paper investigates the failure mechanism and fabric ballistic performance of real-size multi-layer 2D woven fabrics impacted by sharp-edge fragment simulating projectile (FSP). First, the relations between digital fiber shear force and bending rigidity are established under the modified digital element approach (DEA) framework. Then, a systematic parametric study was carried out on the ballistic impact of a 4-inch-long single yarn and 4-inch by 4-inch 2D woven fabric at near fiber level to solve for the relations of digital fiber moment of inertia and ballistic limit. The results show that for the same number of digital fibers per yarn model, the simulated ballistic limits are in direct proportion to digital fiber moment of inertia. The increase of the number of digital fibers per yarn, however, decreases the digital fiber moment of inertia effect on ballistic limits. Second, the 1- to 28-layer real-size 2D woven Kevlar KM2 fabrics are simulated at filament level against FSP on the cluster to estimate the V50 zone. The perforation process and failure mechanism of 4-layer fabric is investigated and analyzed in detail. The simulation results demonstrate the deformed fabric shape with respect to time and the damage modes at the impact area. Numerical results are compared with standard ballistic test results.

Differentiation of Traumatic Osteoporotic and Non-Osteoporotic Vertebral AO A3 Fractures by Analyzing the Posterior Edge Morphology—A Retrospective Feasibility Study

Background: Differentiation between traumatic osteoporotic and non-osteoporotic vertebral fractures is crucial for optimal therapy planning. We postulated that the morphology of the posterior edge of the cranial fragment of A3 vertebral fractures is different in these entities. Therefore, the purpose of this study is to develop and validate a simple method to differentiate between osteoporotic and non-osteoporotic A3 vertebral fractures by morphological analysis. Methods: A total of 86 computer tomography scans of AO Type A3 (cranial burst) vertebral body fractures (52 non-osteoporotic, 34 osteoporotic) were included in this retrospective study. Posterior edge morphology was analyzed using the sagittal paramedian slice with the most prominent shaped bulging. Later, the degree of bulging of the posterior edge fragment was quantified using a geometric approach. Additionally, the Hounsfield units of the broken vertebral body, the vertebra above, and the vertebra below the fracture were measured. Results: We found significant differences in the extent of bulging comparing osteoporotic and non-osteoporotic fractures in our cohort. Using the presented method, sensitivity was 100%, specificity was 96%. The positive predictive value (PPV) was 94%. In contrast, by evaluating the Hounsfield units, sensitivity was 94%, specificity 94% and the PPV was 91%. Conclusions: Our method of analysis of the bulging of the dorsal edge fragment in traumatic cranial burst fractures cases allows, in our cases, a simple and valid differentiation between osteoporotic and non-osteoporotic fractures. Further validation in a larger sample, including dual-energy X-ray absorptiometry (DXA) measurements, is necessary.

Notes on Attic Inscriptions

IG I2 80 +; Paton, The Erechtheum (1927), 449–450; Wade-Gery, JHS LI (1931), 82; Ferguson, Treasurers of Athena 176; Dinsmoor, AJA XXXVI (1932), 312; Deubner, Attische Feste 19; SEG X 28; Raubitschek, Dedications from the Athenian Akropolis 323.The editio minor publication of this decree curiously failed to take into account Wilhelm's discussion of its epigraphical problems. The facts were correctly stated by him. Fragment b has its left margin preserved, and since the width of the stone can be determined from fairly certain restorations in fragment a, considerably more sense can be made out of the third part, the πάτρια of the Praxiergidai, than either Ziehen or Hiller attempted.EM 6629; three fragments of Pentelic marble with back preserved. Fragment a has its top preserved, fragment b its left edge, fragment c its right edge. Original thickness 0·065 m., but the back slopes to each edge. Parts I and II are cut with a horizontal chequer of 0·0106 and a vertical chequer of 0·0104 with chisels measuring 9, 7·5, 6, and 4 mm. Part III is cut with a horizontal chequer of 0·0129 and a vertical chequer of 0·0126 with chisels measuring 11, 9, 7·5, and 4 mm.