Morphometric Study of Suprascapular Notch and Its Variations in Dried Human Scapulae

The study was undertaken to see the variation of the suprascapular notch. The notch is present on the superior border of the scapula near the root of coracoid process. It is roofed by the superior transverse ligament and is converted into foramen for the passage of suprascapular nerve. The study was carried out on 121 scapulae in the department of Anatomy RMC Loni, Ahmednagar. The parameters included in the study were presence of notch, shape of notch, transvers length of notch, edge of notch, ossification of transverse ligament and other finding were also noted. The parameters were measured by Vernier calliper and appropriate statistical tests were applied. The supra-scapular notch was present in 82.64% of scapulae. U Deep shaped notch was most common shape followed by J shallow shaped notch. Round edge at the depth of the notch was more common. The knowledge of suprascapular notch variations is of great importance for surgeons performing suprascapular nerve decompression especially by means of endoscopic techniques. Our anatomical study helps the clinicians before planning a surgery.

Numerical Study of a Plate with a Pre-Cracked Circular Notch

In the recent years, the study of the behaviour of damaged structures has been focused on cracked components in presence of an extensive material yielding at the crack tip; under this condition, linear elastic fracture mechanics theory (LEFM) is not able to describe the real plastic zone shape and size. Within this work, an extensive numerical analysis, based on elastic plastic fracture mechanics theory (EPFM), of the plastic zone size at the tip of a Mode I pre-crack at the notch edge in a plate is presented.

Fatigue Damage Mechanism Analyses of Oriented Sheets of Polymethyl Methacrylate Glasses

To understand the damage mechanism and obtain the fatigue life of the oriented sheets of polymethyl methacrylate (PMMA) glasses, the quasi-static compression tests and the constant amplitude fatigue testing with two notch stress concentration factors are carried out respectively, using the CSS44100 electromechanical universal materials testing machines and a MTS servohydraulic testing machine. The damage region and fracture section of the deformed and failed sheet samples are examined with the aid of an optical microscopy. The results show that, 1) the oriented PMMA glasses drawn through vertical bi-direction have remarkable thermomechanical anisotropic characteristic, that is, it has the higher hardness and strength along the normal direction of the sheet panel, it will burst out and scatters into bigger pieces under the perforation; 2) the S-N curve of the oriented sheet specimens shows that its fatigue life is not sensitive on the notch at lower amplitude stress levels; and 3) the crack initiation of the oriented PMMA glasses often originates the interbeds area or mid region of the notch edge under fatigue cycle loading.

Tensile Tests on High Strength Steel Q345 Notched Plates with the Moderate Thickness

In order to study fracture mechanics of high strength steel with the moderate thickness, fracture tests were performed on 10 elliptical notched plates with the thickness of 16mm fabricated from high strength steel Q345. The effect of notch sharpness (the ratio of the length of short axis to that of long axis of elliptic notch, b/a) and notch depth (the ratio of the length of long axis of elliptic notch to the width of plate, a/w) on fracture model of high strength steel was examined. Test results show that the first crack initiates at the notch edge. The fracture ductility is low for the specimens with the sharper notch (a smaller ratio b/a), and the point of crack load lies in hardening phase of load-displacement curve. The fracture ductility is high for the specimens with the obtuse notch (a bigger ratio b/a), and the point of fracture load lies in necking phase of load-displacement curve. There is no qualitative relationship of fracture ductility and the notch depth (a/w). The ultimate strength of notched plates is independent of the notch sharpness (b/a) and notch depth (a/w).