Preliminary measurements of lumbar spine kinematics and stiffness

The purpose of the presented study was the experimental measurement of lumbar spine stiffness and its range of motion. The dependence of torsion moment of lumbar spine segment on deflection of flexion, extension and torsion was observed during experiments. Stiffness of spine segment was determined from measured data. Human lumbar spine was used for verification of the experimental technique. The sample consisted of one lumbar vertebrae composed by five vertebral bodies and four intervertebral discs. All muscles were removed, however all ligaments were preserved. Experiments were ca rried out on the test system MTS 858.2 MiniBionix, where loading by axial force and torsion moment is possible at the same time. Special Modular Bionix Spine Test Fixator, attached to the test system was used for the measurements. Loading was controlled kinematically (gradual turning) by keeping the axial force equal zero. Measurement was timedependent. The results of these experiments are going to be used as input data for creating a model of artificial lumbar spine and new type of artificial disc replacement

The Effect of Alloying on Mechanical Properties of Advanced High Strength Steels

Quenching and partitioning process with incorporated incremental deformation was optimized for six high strength steels with various contents of carbon (0.4-0.6%), manganese (0.6-1.2), silicon (2-2.6%) and chromium (0.8-1.3%). The optimization was gradually done for each steel with respect to the final microstructures and properties. The effect of cooling rate, quenching and partitioning temperature on microstructure development was further investigated. Interesting combinations of mechanical properties were obtained, with tensile strength in the region of 1600-2400 MPa and ductility of 6-20%

High Versatility of Niobium Alloyed AHSS

The effect of processing parameters on the final microstructure and properties of advanced high strength CMnSiNb steel was investigated. Several processing strategies with various numbers of deformation steps and various cooling schedules were carried out, namely heat treatment without deformation, conventional quenching and TRIP steel processing with bainitic hold or continuous cooling. Obtained multiphase microstructures consisted of the mixture of ferrite, bainite, retained austenite and M-A constituent. They possessed ultimate tensile strength in the range of 780-970 MPa with high ductility A5 mm above 30%. Volume fraction of retained austenite was for all the samples around 13%. The only exception was reference quenched sample with the highest strength 1186 MPa, lowest ductility A5 mm = 20% and only 4% of retained austenite

Obróbka Q-P dla stali o zawartości 0.2% C

In steels which are treated by the quenching and partitioning (Q&P) process, carbon content is one of the crucial parameters because carbon contributes greatly to stabilization of retained austenite and strengthens the material. In the present study, the Q&P process was gradually optimised for two low-alloyed steels with 0.2 % carbon content and with and without Cr addition. The results show that the cooling rate, as well as the austenitizing temperature, has a pronounced effect on microstructure evolution. The strength and elongation in the Mn, Si and Cr-alloyed steel was approx. 900 MPa and more than 30 %, respectively.W stalach poddanych obróbce hartowania i partycjonowania (Quenching and Partitioning – Q&P), zawartość węgla jest jednym z kluczowych parametrów, ponieważ węgiel znacząco wpływa na stabilizacje austenitu szczątkowego i umacnia materiał. W niniejszych badaniach obróbka Q&P była stopniowo optymalizowana dla dwóch niskostopniowych stali o zawartości węgla 0, 2% zawierających dodatek chromu oraz bez tego dodatku. Wyniki pokazują wyraźny wpływ szybkości chłodzeniaoraz temperatury austenityzacji na ewolucje mikrostruktury. Wytrzymałość na rozciąganie oraz wydłużenie do zerwania w manganowo-krzemowo-chromowej stali wyniosły odpowiednio ok.900 MPa oraz ponad 30%

High Versatility of Niobium Alloyed AHSS

The effect of processing parameters on the final microstructure and properties of advanced high strength CMnSiNb steel was investigated. Several processing strategies with various numbers of deformation steps and various cooling schedules were carried out, namely heat treatment without deformation, conventional quenching and TRIP steel processing with bainitic hold or continuous cooling. Obtained multiphase microstructures consisted of the mixture of ferrite, bainite, retained austenite and M-A constituent. They possessed ultimate tensile strength in the range of 780-970 MPa with high ductility A5mm above 30%. Volume fraction of retained austenite was for all the samples around 13%. The only exception was reference quenched sample with the highest strength 1186 MPa, lowest ductility A5mm = 20% and only 4% of retained austenite

Bukan Melayu wajar pelajari silat

Although recent work has begun to establish that early modern plagues had selective mortality effects, it was generally accepted that the initial outbreak of Black Death in 1347‐52 was a “universal killer.” Recent bioarchaeological work, however, has argued that the Black Death was also selective with regard to age and pre‐plague health status. The issue of the Black Death's potential sex selectivity is less clear. Bioarchaeological research hypothesizes that sex‐selection in mortality was possible during the initial Black Death outbreak, and we present evidence from historical sources to test this notion