Effect Of Bending Loads Research Articles

Development of ductile fracture modelling approach in ship impact simulations

A fracture modelling approach is developed to provide predictions in shell element simulations. MSSRT criterion is employed and combined with the modified BWH criterion in the fracture scaling framework to mitigate the mesh size sensitivity. Meanwhile, the effect of bending loads on the fracture prediction is considered by introducing the deformation mode indicator in the model. The predictive capability of the developed fracture model is evaluated by simulating penetration tests of the double hull structure. Reliable predictions of fracture initiation and propagation are yielded with varying mesh sizes. Typical failed elements in the double hull FE model are analyzed, with emphasis given on the evolution of damage for different through-thickness integration points. Based on this, the effects of bending loads on the fracture prediction are discussed in detail. It is demonstrated that the present fracture model can capture the fracture behavior of shell elements with sufficient engineering accuracy. This is especially relevant in the evaluation of ship impact analysis where limited knowledge of the material behavior is available. Although bending is not the dominated deformation mode in the double hull structure, the inclusion of the bending effects in the fracture model tends to provide more consistent prediction results.

Multi-Scale Simulation of Two-Dimensional Chloride Transport Under the Effect of Bending Load in Concrete

Chloride transport in marine concrete under loading is the main cause of its structural deterioration. The traditional numerical simulation assumes that the coefficient of chloride transport is constant, resulting in a large deviation in the prediction results. Based on the porous medium theory, micromechanics theory, and the idea of equivalent homogenization, a multi-scale model of the effective diffusion variable coefficient of chloride transport under bending load was established, which was calculated and programmed by the numerical analysis. The results show that the prediction values of the two-dimensional variable coefficient model are basically consistent with those in the literature, and the prediction accuracy is significantly improved. In addition, the theoretical simulation proves that the bending load affects the porosity of the cement matrix, and then the diffusion coefficient of chloride is changed in concrete. The compression zone can slow down the chloride transport process, while tension zone will accelerate it. The chloride concentration under tension zone is 42.1% higher than that under compression zone when the diffusion time is 200 days and the concrete depth is 15 mm.

Biomodeling and numerical analysis of upper limb under the effect of bending loads in forearm

The study of biological systems today by the application of numerical simulations allows to obtaining analysis of structural mechanical behavior in components of the entire human body. In this research work it is presented the mechanical behavior of radio and ulna bones from the biomodeling of their tissues and how they react under the effect of bending loads. The biomodel developed consists in two kind of material (bones tissues trabecular and cortical) and contact consideration between bones are taking into consideration. This kind of biological system is very difficult to simulated, because the kind of assembly that it has. Nevertheless, results tend to reproduce the manner the system performs.

Modeling Chloride Diffusion Coefficient of Steel Fiber Reinforced Concrete under Bending Load

The chloride diffusion coefficient is the most important parameter when predicting chloride ingress in concrete. This paper proposed a model for calculating the chloride diffusion coefficient of steel fiber reinforced concrete (SFRC). Considering the concrete structures in service are usually subjected to external loads, the effect of bending load was discussed and expressed with a stress factor ks in the model. The chloride diffusion coefficient of cement paste was calculated with capillary porosity and then used to predict the chloride diffusion coefficient of SFRC. Some factors in the model were determined with experimental results. Chloride bulk diffusion tests were performed on SFRC and plain concrete (without fiber) specimens under bending load. SFRC showed slightly better chloride resistance for unstressed specimens. The compressive stress decreased the chloride diffusion coefficient of SFRC, while it caused no change in plain concrete. For the tensile zone, the chloride resistance of concrete was improved significantly by adding steel fibers. Overall, SFRC performed better chloride resistance, especially under bending load. The proposed model provides a simple approach for calculating the chloride diffusion coefficient of SFRC under bending load.

Effect of loading type on the fatigue strength of asymmetric and symmetric transverse non‐load carrying attachments

AbstractThis study considers the effect of bending loading and the symmetry of joints on the fatigue strength of transverse non‐load carrying attachments. Conventionally, the fatigue strength of a welded joint has been determined without taking these factors into account. Experimental and finite element analyses were carried out and both methods showed that both loading type and symmetry have an influence on the fatigue resistance of a welded joint. Under tensile loading, the fatigue strength of asymmetric T‐joints was higher than that of symmetric X‐joints. Respectively, the fatigue resistance of tested joints improved explicitly when the external loading was bending. The finite element analysis was in good agreement with the test results in the joints subjected to tension but gave very conservative results in the joints subjected to bending.

Finite element analysis on bending fretting fatigue of 316L stainless steel considering ratchetting and cyclic hardening

Based on a simplified equivalent two-dimensional (2-D) plane strain finite element model with an equivalent normal force obtained from the three-dimensional (3-D) finite element model, the bending fretting fatigue process of 316L stainless steel is simulated numerically by ABAQUS code. In the simulation, the effects of ratchetting and cyclic hardening features on the fretting fatigue process of 316L stainless steel are discussed by implementing an advanced cyclic elasto-plastic constitutive model into ABAQUS code as a user material subroutine (UMAT). The model describes the ratchetting and cyclic hardening features of 316L stainless steel very well. From the numerical simulation, the effects of bending load and normal force on the bending fretting fatigue of 316L stainless steel are addressed, and then the crack initiation locations and the failure lives are predicted by using Smith–Watson–Topper critical plane criteria. Comparison with the corresponding experiments shows that the predicted results are in good agreement with the experimental ones.

The effect of load-controlled bending load on the failure pressure of wall-thinned pipe elbows

In this research, burst tests were conducted on real-scale elbow specimens, each with an artificial local wall-thinning defect, under combined internal pressure and constant in-plane bending load, as well as under simple internal pressure, to evaluate the effect of load-controlled bending load on the failure pressure of locally wall-thinned pipe elbows. Ninety-degree, 65A Schedule 80 elbows, with wall-thinning defects in the intrados and extrados, were used as specimens. The bending loads were in-plane opening- and closing-mode bending, applied in load-control mode. The results clearly indicated that a load-controlled in-plane bending load reduced the failure pressure of wall-thinned pipe elbows, in contrast to observations previously made under displacement-controlled bending conditions. The effect of the bending load was more significant for opening-mode than for closing-mode bending, regardless of the wall-thinning location in the elbow. Also, the effect was greater when the wall-thinning defect was located in the intrados region of the elbow, rather than the extrados region. Existing models that have been proposed to evaluate the failure of wall-thinned elbows under simple internal pressure conservatively predicted the failure pressure of elbows subjected to a combined internal pressure and load-controlled bending load.

Finite Element Simulation of Bending Fretting Fatigue Considering Ratchetting and Cyclic Hardening

Based on a simplified equivalent 2-D plane strain finite element model, the bending fretting fatigue process of 316L stainless steel is simulated numerically by ABAQUS code. In this simulation, the effect of ratchetting on the fretting fatigue process is discussed by implementing an advanced cyclic elasto-plastic constitutive model for cyclic hardening materials into ABAQUS code as a user material subroutine (UMAT). From the numerical simulation, the effect of bending loads on the bending fretting fatigue of 316L stainless steel is addressed, and then the failure lives are predicted by using Smith-Watson-Topper critical plane criteria. Comparison with the corresponding experiments shows that the predicted results are in good agreement with the experimental ones.

The effect of bending loads on the dynamic behaviors of a rolling guide

Dynamic behaviors of ball-type contact surfaces under unbalanced bending loads are studied using point-to-point analysis, threedimensional finite element simulation based on the Hertz Contact Theory, and a modal test. Results derived from these models are very similar but the Finite Element Model provides the best results since it allows for more elements of study, such as the steel ball, carriage, rail etc. In the study, results also show that frequencies vary slightly, but there is an obvious change in shapes. Therefore, the contact stiffness in simulations must be properly selected with the conclusion that different external loadings may affect the dynamic characteristics of such structures significantly.

Collapsing Pressure of Casing Located at the Bend Part of Casing-Exit Sidetracking Well

Depending on the mechanical characteristics of casing located at the bending part of sidetrack horizontal well, the calculation model of casing collapsing strength under the effect of bending load is established, and corresponding theoretical formulae is derived. During the process of deducing formulas, the influence of bending load on the casing section out of roundness is ignored, which made the calculation formula benefits intuition and practicality comparing to the T.Tamano formula. The result of this paper is verified through the simulation value and laboratory test of casing used in the Jilin oilfield. It shows that the formula of this paper can meet the engineering commands; the axial load is significant to affect casing collapsing strength, and in the actual production process should be strictly controlled.

Effect of bending load on the creep failure behaviour of a pressurised thick walled CrMoV pipe weldment

This paper describes the results of a finite element investigation into the effects of bending on the creep failure behaviour of an internally pressurised thick walled pipe weld. The material properties used were those for a service-exposed 1/2Cr1/2Mo1/4V:2 1/4Cr1Mo weldment at 640 °C. The peak rupture stresses in each material zone, which were obtained from steady-state analyses, were used to predict failure lives for a range of bending load levels. The rupture stresses showed very little variation across the heat-affected zone, in the dominant stress regions, for low and moderate bending loads. However, the variation is more significant when the bending load is high but still within the allowable limits of design codes. The results obtained indicate that, in addition to the pressure, there is a higher probability of type IV cracking occurring, when an external (system) bending load is present. The results obtained were compared with those obtained for the uniform end load cases.

The use of X-ray diffraction measurements to determine the effect of bending loads on internal stresses in aluminum inclusions embedded in a unidirectional graphite-fibre/PMR-15 composite

A testing methodology for the determination of residual thermal stresses in the polymer-matrix of unidirectional polymer-matrix composites has been proposed in Ref. [1] [Benedikt B, Kumosa M, Predecki PK, Kumosa L, Castelli MG, Sutter JK. An analysis of residual thermal stresses in a unidirectional graphite/PMR-15 composite based on the X-ray diffraction measurements. Composites Science and Technology (in press)]. The methodology is based X-ray diffraction (XRD) measurements of residual strains in embedded metallic particles. The residual stresses in the polymer matrix can be extracted from the X-ray strains in the particles using the visco-elastic Eshelby method for multiple inclusions. The purpose of this work has been to show that the newly developed experimental/analytical methodology can also be applied to composites subjected to external loads, in this case: spherical aluminum particles embedded in a unidirectional graphite/PMR-15 composite subjected to four-point bending loads. The total stresses and strains in the aluminum particles caused by residual thermal stresses in the composite and the applied stresses generated by four-point bending have been determined by XRD measurements under low bending displacements. Subsequently, the total strains and stresses in the aluminum particles have been numerically predicted by applying elastic and visco-elastic laminate theories and the Eshelby method. It has been shown in this research that not only the residual thermal strains and stresses in the aluminum particles and the matrix can be determined by using the proposed technique but also the effect of external loads on the stresses and strains in the particles can be monitored. This research has provided another verification of the newly proposed methodology presented in Ref. [1].

Gripping Characteristics of a Wedge-Type Power Chuck. Bending Load Dependence on Bending Stiffness.

In this paper, the effect of bending load on bending stiffness of a wedge-type power chuck with three top jaws is investigated. Bending tests of works with different diameters were performed in which the deflection of works were measured. The investigation showed that the bending stiffness of the chuck-work system significantly depends on the bending load when the bending load is increasing. The bending stiffness varies with gripping force and the ratios of the diameter of works to the gripping length of jaws. There is no effect of the bending load on the bending stiffness when works are clamped under the gripping condition in which gripping lengths are 0.8 times an large as work diameters. This gripping condition is also acceptable for the damping efficiency of the system.

Unstable Fracture of Mild Steel Plate under Stretching and Plate Bending

On the large structures such as ships's hull, tank structure and etc., various loads are acting. In some structural members, therefore, out-of-plane stress due to bending often may become larger than in-plane stress due to stretching.In this report, the characteristics of brittle fracture initiation of mild steel plate with a through crack under the combined action of stretching and plate bending have been studied both experimentally and theoretically using the linear elastic fracture mechanics (L. E. F. M.).As the results of this investigation, the following conclusions are obtained.(1) Effect of bending load on the characteristics of brittle fracture initiation can be evaluated over a fairly wide range by the criterion proposed by authors using the concept of energy balance based on L. E. F. M.(2) From the results of eccentrically loaded and center-notched Deep Notch Tests, it is extremely safe for design that the maximum surface stress is considered as the equivalent fracture stress at higher temperature than -180°C.(3) The evaluation of fracture phenomena using the equivalent K-value proposed by authors is confirmed to be fairly good for expressing the behaviour of the material such as mild steel plate.