Comparative Stress Analysis Research Articles

Сравнительный анализ напряжений в несимметричных многослойных композитных пластинах на основе асимптотической теории и трехмерного конечно-элементного расчета

Сравнительный анализ напряжений в несимметричных многослойных композитных пластинах на основе асимптотической теории и трехмерного конечно-элементного расчета

Comparative analysis of stress on faculty and students based on salivary IgA

Abstract The goal of this project is to test students and faculties stress levels in their saliva compared between the beginning of this semester and the end of the semester. IgA levels are influenced by many physiological factors, including the hormones associated with stress. The findings conclude that there is significance between IgA levels in a student or faculty based on hours since they had left class and hours until they have class. Students and faculty showed a correlation between IgA and time since being in class or work (p-value = 0.03), however no significance of the duration of the expected rest period (p-value = 0.71). The significance of this finding is that students and faculty tend to be more stressed after being in class/work based on IgA levels in their saliva.

Comparative analysis of stress in a new proposal of dental implants

The purpose of this study was to compare, through photoelastic analysis, the stress distribution around conventional and modified external hexagon (EH) and morse taper (MT) dental implant connections. Four photoelastic models were prepared (n=1): Model 1 – conventional EH cylindrical implant (Ø 4.0mm×11mm - Neodent®), Model 2 – modified EH cylindrical implant, Model 3 – conventional MT Conical implant (Ø 4.3mm×10mm - Neodent®) and Model 4 – modified MT conical implant. 100 and 150N axial and oblique loads (30° tilt) were applied in the devices coupled to the implants. A plane transmission polariscope was used in the analysis of fringes and each position of interest was recorded by a digital camera. The Tardy method was used to quantify the fringe order (n), that calculates the maximum shear stress (τ) value in each selected point. The results showed lower stress concentration in the modified cylindrical implant (EH) compared to the conventional model, with application of 150N axial and 100N oblique loads. Lower stress was observed for the modified conical (MT) implant with the application of 100 and 150N oblique loads, which was not observed for the conventional implant model. The comparative analysis of the models showed that the new design proposal generates good stress distribution, especially in the cervical third, suggesting the preservation of bone tissue in the bone crest region.

Orthogonal Variable Thickness Cutting Modeling of Surface Milling and Physical Fields Simulation

When milling the complex surface with the ball-end milling cutter, the cutting thickness always changes in ball-end milling process. At present, many milling models are actually simplified with unchanged cutting thickness, which ignores the ball-end milling cutting with complex tool-work piece relationship. According to the characteristics of the ball-end milling, orthogonal variable thickness cutting model is established based on the study of three-dimensional contact relationship of tool-work piece. The simulation of the stress field and the temperature field in hardened steel Cr12MoV orthogonal variable thickness cutting process is conducted, and comparative analysis of stress and temperature field distribution of high-speed milling and conventional milling is made. The cutting model of orthogonal variable thickness cutting can reflect the characteristics of surface milling accurately, which can be further used in the study of changing characteristics of physical fields and the optimization of cutting and tool parameters to improve the machining efficiency and quality.

Komparativna analiza naponskog stanja gornjih delova noseće konstrukcije portala kod portalnih dizalica

Komparativna analiza naponskog stanja gornjih delova noseće konstrukcije portala kod portalnih dizalica

Comparative Analysis Of Stress In Hyperelastic Mooney-Rivlin And Zahorski Materials Using Adina Software

Abstract The paper presents a comparative analysis of stress in hyperelastic Mooney-Rivlin and Zahorski materials. The comparison was performed in ADINA software with the example of a cube loaded with linear displacement of side walls in y and z directions with coefficient of strain λ = 2 The conclusions from the analysis were presented in the Conclusion section.

NUMERICAL STUDY OF STRESS AND DEFORMATION IN THE CONSTRUCTION OF THE DOUBLE-LAYER ROOF FOR VERTICAL CYLINDRICAL STEEL OIL TANKS

The present article deals with the calculation and comparative analysis of stress and deformation in the double-layer roof for large oil tanks when using three different modules: a parallelepiped, a triangular pyramid and a rectangular pyramid. For modeling stress and deformation in the supporting elements of a dome roof the method of finite elements is the most suitable one to be applied. For the analysis and optimization of the construction of a double- layer dome roof with the diameter 60-100 meters software package SAP2000 was used, which enables optimizing structural modules, at the same time reducing the dead load, as well as the stress and deformation in the rods. The article provides information on dependence of the dead load and stress on the distance between the layers of the roof, along with the numerical values of

Comparative Analysis of Stress of Two Typical Micro-Displacement Control Platform

This paper selects two typical micro-displacement control platforms,and conducts comparative analysis of strength of their flexible guiding mechanism.Stress expressions of flexible guiding mechanism are respectively derived to obtain the relationship between the maximum stress and geometric parameters and the relationship between tensile stress and bending stress.with moving the same displacement,the difference of stress of the two micro-displacement control platforms is small,and can be ignored.

Comparative stress analysis of delayed and immediate loading of a single implant in an edentulous maxilla model.

Stress distribution in peri-implant bone in an edentulous maxilla following delayed and immediate loading implant and the effect of implant length on the maximum stress were evaluated by using two kinds of finite element analyses. A threaded implant was loaded with a 100 N vertical force, either immediately or delayed, and examined by finite element analysis with a simple contact relation or a bonding interaction between the implant and the bone, respectively. Higher stresses were observed in cortical bone around the implant neck following delayed loading and in the trabecular bone around the implant threading in the immediate loading model. The maximum stress in the immediate loading model was dramatically higher than in delayed loading. Increased implant length caused decrease in bone stresses in both loading models. Though the stress level was higher, the decrease in the maximum trabecular bone stress in immediate loading was profound.

Finite element modelling of sandwich panels with graded core under various boundary conditions

AbstractSandwich panels are widely used in the aerospace industry instead of solid plates due to their high flexural stiffness-to-weight and flexural strength-to-weight ratios. However due to the mismatch of properties between the face sheets and the core, stress concentrations can occur at the face sheet/core interfaces, often leading to delamination. One possible solution to this problem is the introduction of a graded core — a core in which the properties vary gradually from the face sheets to the core centre, eliminating any abrupt changes in properties. In this paper a 3D finite element method, fully validated through comparison with results from the literature and a 3D elasticity solution, is applied to modelling of sandwich panels with graded core. The approach makes use of graded elements to study the effect of varying the boundary conditions on the elastic deformation of the panel subject to uniformly distributed loading. Comparative analysis of stress and displacement fields in sandwich panels with homogeneous and graded cores is carried out under various combinations of simply supported, clamped and free edges.

Performance of functionally graded plates under localised transverse loading

This paper presents a study of the bending of an isotropic functionally graded plate under localised transverse load through a combination of analytical and computational means. The analytical modelling is based on the recently developed three-dimensional elasticity solution, expanded to cover different loading types, whilst the Finite Element model uses graded isoparametric elements. The plate under consideration is assumed to be simply supported, with Young’s and shear moduli varying exponentially through the thickness and the Poisson’s ratio constant. Comparative analysis of stress and displacement fields in functionally graded and homogeneous plates subjected to uniformly distributed and patch loadings is carried out.

STRESS ANALYSIS OF (001) PREFERRED ORIENTED BiFeO3 AND Bi(Cr0.03Fe0.97)O3 FILMS

ABSTRACT Comparative stress analysis of (001)-preferred oriented BiFeO3 (BFO) and Bi(Cr0.03Fe0.97)O3 (BCF) films formed by the chemical solution deposition method on LaAlO3 and La0.27Sr0.73Ta0.35AlO3 substrates, using high resolution X-ray diffraction (HRXRD), sin2ψ method, micro-Raman and high resolution transmission electron microscopy (HRTEM) was carried out. Tensile stresses are found in all films compared to the compressive stresses measured by HRTEM. Compressive stresses occur at the interface due to lattice mismatch between the substrates and BFO/BCF. The BFO films contained higher tensile stresses ∼8.57 GPa than the BCF films ∼5.20 GPa. Intrinsic stresses played a larger factor in the residual stress of the films.

Cracks, repair and reconstruction of bucket wheel excavator slewing platform

This paper discusses the results of the investigation of occurrence of cracks in the structure of bucket wheel excavator (BWE) slewing platform, the repair procedure and the reconstruction of the slewing platform. The results of the finite elements analysis (FEA) point out the pronounced stress concentration in the zones of crack occurrence. The values of calculated stresses in the said zones exceed the yield stress of the material. The design solution for the slewing platform reconstruction is chosen based on the comparative analysis of stress–strain states of alternative solutions. The adopted solution enabled the repair and reconstruction in field conditions, without previously dismantling components of the BWE superstructure. Moreover, the regular maintenance procedure has not been impeded. Experimental analysis of the stress state of the reconstructed slewing platform in regular working conditions has confirmed the validity of the reconstruction design. After the reconstruction the BWE has dug up more than 2.9 × 10 6 m 3 of overburden. Visual inspection of slewing platform proved that there are no defects in the structure.

Numerical and experimental stress analysis of a polymeric composite hip joint prosthesis

A comparative stress analysis of a polymeric composite hip joint replacement was performed. A prototype short carbon-fiber reinforced PEEK (CF/PEEK) prosthesis was manufactured by injection molding. Finite element (FE) analysis was conducted on intact femurs and femurs fitted with the CF/PEEK and the titanium prostheses under various loading conditions. FE models were validated by experimental strain gauge measurements by using synthetic femurs. There was a good agreement between the two methods except in the hoop strain of the femur in the calcar region because of the assumption of the isotropic material properties. The stem stresses were lower for the CF/PEEK prosthesis than for the titanium prosthesis. The maximum stress was in the spigot of the CF/PEEK prosthesis, but in the middle third of the stem of the titanium prosthesis. Stress generated in the cement was almost equal for both prostheses although more load was transferred, via cement, to the femur with the CF/PEEK prosthesis because the load transfer took placed over a larger area. An out-of-plane component of the joint load causes higher prosthesis and cement stresses. © 1996 John Wiley & Sons, Inc.

Fatigue fracture of a weld on a weight training frame

A safety critical weld joining a central post to a cross member of a weight training leg press failed due to fatigue crack propagation from the fluctuating loads experienced in service. A comparative stress analysis carried out on the failed weight training leg press and a superficially similar leg press which had given satisfactory service revealed the very poor fatigue design of the failed leg press.

Numerical analysis of stress shielding of platedhuman femur using 3-dimensional finite element method

Conventional compression bone fracture plates sometimes cause osteoporosis under the plate due to their high rigidity. In order to prevent the osteopenia, many researchers have attempted various types of bone plates. To meet the same purpose, a new concept bone plate which have a vicoelastic washer between plate and screw head is introduced. The washer is made of a biocompatible polymer (ultra high molecular weight polyethylene, UHMWPE). This research was performed first to establish a more realistic and detailed plated-bone system using finite element method and second to investigate the effect of the UHMWPE washer on the stress shielding comparing with the conventional plate model. Three-dinensional finite element meshes of the human femur with the conventional and new concept bone plate were generated and the comparative stress analysis of the stress shielding was performed with static half-stance loading condition. The results of analysis showed that the new and conventional bone plate transfer the stress through the bone average 15% and 10% that of the intact bone respecively. However, the local stress in the bone under the new bone plate have increased about 13-150% that of the conventional bone plate depending on the region. Earlier preliminary animal studies showed some promising results. It is suggested that the in vivo and FEM results support the feasibility of the new concept bone plate.

Comparative stress analysis of the sheep femur under physiological loading conditions

Comparative stress analysis of the sheep femur under physiological loading conditions

Development, installation, and initial operation of DIII-D graphite armor tiles

An upgrade of the DIII-D vacuum vessel protection system has been completed. The ceiling, floor, and inner wall have been armored to enable operation of CIT-relevant double-null diverted plasmas and to enable the use of the inner wall as a limiting surface. The all-graphite tiles replace the earlier partial coverage armor configuration which consisted of a combination of Inconel tiles and graphite brazed to Inconel tiles. A new all-graphite design concept was chosen for cost and reliability reasons. The ten minute duration between plasma discharge required the tiles to be cooled by conduction to the water-cooled vessel wall. Using two and three-dimensional analyses, the tile design was optimized to minimize thermal stresses with uniform thermal loading on the plasma-facing surface. Minimizing the stress around the tile hold-down feature and eliminating stress concentrators were emphasized in the design. The design of the tile fastener system resulted in sufficient hold-down forces for good thermal conductance to the vessel and for securing the tile against eddy current forces. The tiles are made of graphite, and a program to select a suitable grade of graphite was undertaken. Initially, graphites were compared based on published technical data. Graphite samples were then tested for thermal shock capacity in an electron beam test facility at the Sandia National Laboratory (SNLA) in Albuquerque, New Mexico, USA. The expected operational heat load to the tiles is 500 W/cm 2 for 10 s over the entire tile during limiter operation and 1000 W/cm 2 over a 2 cm wide band for 10 s for divertor operation. Comparative stress analysis was performed on the basis of 1000 W/cm 2 uniformly distributed on the front surface for 5 s with 10 min between pulses. Prototype tiles survived beam heating to the limit of the beam system which was 1000 W/cm 2 for 4 s or 1750 W/cm 2 for 1.75 s. The electron beam facility at the Sandia National Laboratory was used to deposite higher heat flux in a 2 cm wide band in order to model divertor heat flux conditions. These tests were successful with heat fluxes up to 2500 W/cm 2 for 5 s. Both the ion beam and the electron beam tests produced surface temperatures up to 3100 °C which resulted in minor surface erosion but no structural cracking. Installation of approximately 1600 armor tiles was accomplished in November/December 1987. Initial operation experience with the new armor system is summarized.

Quantitative and comparative stress analysis in human femur under two different static situations by three-dimensional photoelasticity.

Using the three-dimensional photoelastic method a quantitative analysis was carried out on the tension trends in the proximal third of a normal human femur in a stationary weight-bearing situation on two legs. The results obtained show that in this loading situation the maximum stress values (both for tension and compression) are in the area just below the subtrochanteric zone; while going up along the borders of the diaphysis, the tension trends do not vary appreciably. Moreover, the state of the stresses is not constant but varies slightly along the thickness of the bone. The neutral axis is considerably displaced towards the tensile area. A comparison between the stress tension trends in two different static loading situations (one-leg and two-leg support) was carried out. It was found that the maximum tensile stress value in the one-leg position was about 24 times greater than that in the two-leg position and the maximum compression stress value was about 14 times greater than in the two-leg situation.

The Dentatus screw: comparative stress analysis with other endodontic dowel designs

SummaryUsing photoelastic stress analysis, this study shows that the tapered, self‐threading, Dentatus endodontic screw causes severe wedging forces on installation. These stresses are magnified by increases in dowel diameter and the application of occlusal loads. The Dentatus screw produces more severe stress concentrations than the Unitek, Whaledent, Radix, and Kurer dowel designs; this is true both during installation and under load.