Length-change patterns of the medial collateral ligament and posterior oblique ligament in relation to their function and surgery

Purpose To define the length-change patterns of the superficial medial collateral ligament (sMCL), deep MCL (dMCL), and posterior oblique ligament (POL) across knee flexion and with applied anterior and rotational loads, and to relate these findings to their functions in knee stability and to surgical repair or reconstruction. Methods Ten cadaveric knees were mounted in a kinematics rig with loaded quadriceps, ITB, and hamstrings. Length changes of the anterior and posterior fibres of the sMCL, dMCL, and POL were recorded from 0° to 100° flexion by use of a linear displacement transducer and normalised to lengths at 0° flexion. Measurements were repeated with no external load, 90 N anterior draw force, and 5 Nm internal and 5 Nm external rotation torque applied. Results The anterior sMCL lengthened with flexion (p < 0.01) and further lengthened by external rotation (p < 0.001). The posterior sMCL slackened with flexion (p < 0.001), but was lengthened by internal rotation (p < 0.05). External rotation lengthened the anterior dMCL fibres by 10% throughout flexion (p < 0.001). sMCL release allowed the dMCL to become taut with valgus rotation (p < 0.001). The anterior and posterior POL fibres slackened with flexion (p < 0.001), but were elongated by internal rotation (p < 0.001). Conclusion The structures of the medial ligament complex react differently to knee flexion and applied loads. Structures attaching posterior to the medial epicondyle are taut in extension, whereas the anterior sMCL, attaching anterior to the epicondyle, is tensioned during flexion. The anterior dMCL is elongated by external rotation. These data offer the basis for MCL repair and reconstruction techniques regarding graft positioning and tensioning.

Аutomatisation of Calculation Method of Technological Parameters of Wiredrawing with Account of Speed Factor and Material Properties

The article presents the mathematical model worked out for calculating the operating force of the wire drawing. The solution of the problem was achieved by dividing the wire work piece material in the deformation zone into an infinitely small finite elements ij; and, by parting the working area of the die geometry, consisting of crimping cone, drawing cylinder and the radius of curvature between them into infinitely small linear sections. The authors described the conditions for continuity at the finite element line, the dependencies required to determine the geometric grid sizes. To determine the total modified draw force, the authors obtained formulas to describe the stress condition at each point of the finite element, based on the motion equations, equations of velocity fields, the incompressibility condition, the deformation rate intensity, taking into account the speed factor and viscoplastic properties of the work material. The article presents the adequacy of the proposed model.

Comparing the Prediction Capabilities of Artificial Neural Network (ANN) and Nonlinear Regression Models in Pet-Poy Yarn Characteristics and Optimization of Yarn Production Conditions

In the manufacture of yarn, predicting the effect of changing production conditions is vital to reducing defects in the end product. This study compares, for the first time, non-linear regression and artificial neural network (ANN) models in predicting 10 yarn properties shaped by the influence of winding speed, quenching air temperature and/or quenching air speed during production. A multilayer perceptron ANN model was created by training 81 patterns using the Broyden-Fletcher-Goldfarb-Shanno (BFGS) algorithm. The hyperbolic tangent, or TanH, activation function and logistic activation functions were used for the hidden and output layers respectively. Results showed that the ANN approach exhibited a greater prediction capability over the nonlinear regression method. ANN simultaneously predicted all of the 10 final properties of a yarn; tensile strength, tensile strain, draw force, crystallinity ratio, dye uptake based on the colour strengths (K/S), brightness, boiling shrinkage and yarn evenness, more accurately than the non-linear regression model (R2=0.97 vs. R2=0.92). These results lend support to the idea that the ANN analysis combined with optimization can be used successfully to prevent production defects by fine tuning the production environment.

Kineto-Elastic Analysis of a Compound Bow

This paper presents the kineto-elastic analysis of a compound bow which in each side of the limbs has two stacked eccentric cams connected by two inextensible cables and one inextensible string. A large deformation cantilever beam model was created to determine the center trajectories of the cams. The principle of finite element method was applied to calculate the deformation of the limbs by combining small deflections of segmented cantilever beam elements. Another part of this work is the construction of a quasi-static model to simulate the draw process. The displacements of cams, cables and string were analyzed by gradually drawing the bow string. The required draw force as a function of draw length was obtained, and verified by experiments. The kineto-elastic analysis procedure described in this paper can be used later for the optimal design of the shapes of the cams and limbs. The modeling and simulation procedure used for combining elastic components, flexible but inextensible string-cable components, and rigid component in a precision dynamic model of a mechanical system can also be applied to archery bows with more complex configuration, and to other similar mechanical systems.

Fatigue Life Analysis of Mine Hoist Drum

This article is based on a certain type of hoist drum, Moreover, we make the stress and mode analysis for the drum, and make preliminary check on it. Then find the position of the weak section, we calculate the force in each stage of hoisting system and draw force-timing load spectrum,we translate it into stress function of weak link. Based on above studies and conclusion, in line with the materials of the drum and Fatigue characteristic parameters and appropriate fatigue lifetime prediction model, we analysis the fatigue performance, in the end get the distribution of the drum’s fatigue life and the life of plane of weakness.

Investigation of Steady-State Drawing Force and Heat Transfer in Polymer Optical Fiber Manufacturing

The force required to draw a polymer preform into optical fiber is predicted and measured, along with the resultant free surface shape of the polymer, as it is heated in an enclosed cylindrical furnace. The draw force is a function of the highly temperature dependent polymer viscosity. Therefore accurate prediction of the draw force relies critically on the predicted heat transfer within the furnace. In this investigation, FIDAP was used to solve the full axi-symmetric conjugate problem, including natural convection, thermal radiation, and prediction of the polymer free surface. Measured and predicted shapes of the polymer free surface compared well for a range of preform diameters, draw speeds, and furnace temperatures. The predicted draw forces were typically within 20% of the experimentally measured values, with the draw force being very sensitive to both the furnace wall temperature and to the feed rate of the polymer.

Investigation of Polymer Optical Fiber Drawing Force and Heat Transfer

In this study, the force required to draw a polymer preform into optical fiber is predicted and measured, along with the resultant free surface shape of the polymer, as it is heated in an enclosed cylindrical furnace. The applied drawing force affects the degree of chain alignment within the polymer. Chain alignment causes orientational birefringence, an unwanted property that attenuates any propagating optical signal. The draw force is a function of the highly temperature dependent polymer viscosity. Therefore accurate prediction of the drawing force requires a detailed investigation of the heat transfer within the furnace. In this investigation, the full axi-symmetric conjugate problem (including both natural convection and thermal radiation) was solved using the commercial finite element package FIDAP. In addition, the location of the polymer/air interface was solved for as part of the problem and was not prescribed beforehand. Results show that thermal radiation accounts for approximately 70% of the total heating experienced by the deforming polymer, but only 15% of the cooling. The draw force is very sensitive to both the furnace wall temperature and to the feed rate of the polymer. Numerical results compared well with the experimentally measured draw tension and neck-down profiles for several preform diameters, draw speeds, and furnace temperatures. The predicted draw forces were typically within 20% of the experimentally measured values.

Stress in Glass Fibers Induced by the Draw Force

This paper analyzes the viscoelastic phase of the forming process of glass fibers when the viscous and elastic material constants are variable with a coordinate normal to the fiber axis. This condition may be due to either a temperature gradient or a material inhomogeniety as in clad fibers. One employs the equations of classical viscoelasticity and obtains an approximate solution for the fiber stress. The analysis bears out the findings of previous investigators that the force used to draw such fibers from hot preforms or melts produces a viscoelastic stress that has large gradients directed transverse to the fiber axis. As the fiber cools, a strain proportional to the draw force is frozen into the fiber which contributes to the residual fiber stress. The merits of a solution for the frozen stress used by previous investigators is discussed. It is shown that an increase in the draw force can either weaken or strengthen a fiber depending on the attendant physical conditions, and one discusses how this factor may be exploited. The force induced stress is determined theoretically for two specific fibers. An experimental determination of the force-induced stress is given which is in substantial agreement with the theory.