Numerical investigation into thermal buckling of friction pairs in hydro-viscous drive under nonlinear radial temperature distribution

2021 ◽  
pp. 135065012110515
Author(s):  
Qiliang Wang ◽  
Jianmei Wang ◽  
Hongwei Cui ◽  
Jun Wang ◽  
Fan Zhang
Keyword(s):  
Critical Temperature ◽  
Thermal Loading ◽  
Failure Modes ◽  
Outer Edge ◽  
Thermal Buckling ◽  
Radial Temperature ◽  
Thermal Failure ◽  
Boundary Constraints ◽  
Buckling Behavior ◽  
Steel Disc

Thermal buckling deformation can significantly impact the operating performance of hydro-viscous drive. A thermal buckling finite element shell model was established with the nonlinear radial temperature as the thermal loading condition. The thermal buckling behavior of friction pairs was investigated under three different boundary constraints. Moreover, the influence of thickness and material parameters on the critical buckling temperature was discussed. The simulation results coincide with the failure modes of friction pairs in practice, and the most common ones are the coning mode and the potato chip mode. The ability to resist thermal buckling deformation can be improved as the thickness increases. In addition, the steel disc with outer edge simply supported is more prone to thermal buckling, because the critical temperature is minimum. The thermal expansion coefficient is the primary factor in thermal buckling study, which is inversely proportional to the critical temperature. These provide a theoretical basis for avoiding thermal failure of friction pairs in a hydro-viscous drive.

scholarly journals Buckling behavior of cold-formed steel columns at both ambient temperature and simulated fire conditions

Fire Research ◽  
2016 ◽  
Author(s):  
Hélder D. Craveiro ◽  
João Paulo C. Rodrigues ◽  
Luís M. Laím
Keyword(s):  
Experimental Investigation ◽  
Ambient Temperature ◽  
Cross Sections ◽  
Failure Modes ◽  
Steel Columns ◽  
Buckling Behavior ◽  
Wide Range ◽  
Cold Formed Steel ◽  
Simulated Fire ◽  
Fire Conditions

Cold-formed steel (CFS) profiles with a wide range of cross-section shapes are commonly used in building construction industry. Nowadays several cross-sections can be built using the available standard single sections (C, U, Σ, etc.), namely open built-up and closed built-up cross-sections. This paper reports an extensive experimental investigation on the behavior of single and built-up cold-formed steel columns at both ambient and simulated fire conditions considering the effect of restraint to thermal elongation. The buckling behavior, ultimate loads and failure modes, of different types of CFS columns at both ambient and simulated fire conditions with restraint to thermal elongation, are presented and compared. Regarding the buckling tests at ambient temperature it was observed that the use of built-up cross-sections ensures significantly higher values of buckling loads. Especially for the built-up cross-sections the failure modes were characterized by the interaction of individual buckling modes, namely flexural about the minor axis, distortional and local buckling. Regarding the fire tests, it is clear that the same levels of restraint used in the experimental investigation induce different rates in the generated restraining forces due to thermal elongation of the columns. Another conclusion that can be drawn from the results is that by increasing the level of restraint to thermal elongation the failure of the columns is controlled by the generated restraining forces, whereas for lower levels of restraint the temperature plays a more important role. Hence, higher levels of imposed restraint to thermal elongation will lead to higher values of generated restraining forces and eventually to lower values of critical temperature and time.

Asymmetric Thermal Buckling of Imperfect FGM Circular Plates with Rotationally Restrained Edge

2020 ◽  
Vol 20 (12) ◽  
pp. 2050127
Author(s):  
S. V. Levyakov
Keyword(s):  
Critical Temperature ◽  
Temperature Rise ◽  
Material Properties ◽  
Thermal Loading ◽  
Plate Theory ◽  
Nonlinear Eigenvalue Problem ◽  
Mode Shapes ◽  
Effect Of Temperature ◽  
Circular Plates ◽  
Governing Equations

The paper addresses the problem of asymmetric buckling of geometrically imperfect circular plates undergoing large axisymmetric deflections under thermal loading. The plate edge is assumed to be immovable in the radial direction and elastically restrained against bending rotation. The plate material is graded in the thickness direction and dependence of the material properties on temperature is taken into account. The governing equations are derived using the von Karman nonlinear plate theory and the concept of physically neutral surface. It is shown that, when subjected to increasing temperature, the plate initially bends into a figure of revolution and then buckles into asymmetric mode with local circumferential waves. To determine the critical temperature rise, a nonlinear eigenvalue problem is formulated by linearizing the governing equations about the axisymmetric state of equilibrium and solved using power-series expansions. The effect of temperature-dependent material properties, rotational spring stiffness and initial geometric imperfection on the critical temperature rise and buckling mode shapes is studied.

scholarly journals Fatigue Behaviors of Resistance Spot Welds for 980 MPa Grade TRIP Steel

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1086
Author(s):  
Heewon Cho ◽  
Sangwoo Nam ◽  
Insung Hwang ◽  
Je Hoon Oh ◽  
Munjin Kang ◽  
...  
Keyword(s):  
Fatigue Life ◽  
Failure Mode ◽  
Trip Steel ◽  
Failure Modes ◽  
Propagation Speed ◽  
Outer Edge ◽  
Fatigue Load ◽  
Resistance Spot ◽  
Fracture Surfaces ◽  
Pull Out

The fatigue life of the resistance spot weld of 980 MPa grade transformation induced plasticity (TRIP) steel was investigated and failure modes and fracture surfaces according to the fatigue load were analyzed. The fatigue life according to the nugget size was observed by using two electrodes with face diameters of 8 mm and 10 mm. When an electrode face diameter with 10 mm was used, the nugget size was large, and the fatigue life was further increased. After the fatigue test, three types of failure modes were observed, namely pull-out, plug, and heat affected zone (HAZ) failure, depending on the fatigue load. The fracture surfaces in each failure mode were analyzed. In all failure modes, a crack was initiated in the HAZ region, which is the interface between the two materials in all failure modes. In the case of pull-out failure, the crack propagates as if it surrounds the nugget at the outer edge of the nugget. In the case of HAZ failure, the crack propagates in the thickness direction of the material and outward in the nugget shell. Plug failure occurs with pull-out failure and HAZ failure mixed. The propagation patterns of cracks were different for each failure mode. The reason why the failure mode and the fracture surface are different according to the fatigue load is that the propagation speed of the fatigue crack is fast when the fatigue load is relatively large and is slow when the fatigue load is low.

Experimental Study of the Cold Restart of a Pipeline Filled With a Gelled Waxy Oil

2002 ◽  
Author(s):  
Scott A. Miles ◽  
G. Egan Wheeler ◽  
John W. Hall
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Particle Image ◽  
Initial Conditions ◽  
Gel Strength ◽  
Radial Temperature ◽  
Waxy Oil ◽  
Start Up ◽  
Image Velocimetry ◽  
Parameter Ranges

Experiments were conducted on the flow field start up behavior of a gelled waxy oil in a pipeline. A simulant fluid was used to mimic the low temperature rheology of crude oil. The break down of the gelled simulant fluid was studied during different startup conditions. It is shown that the “failure mode,” or manner and location in which the gelled simulant fluid breaks down, is closely related to both the temperature of the gel and the cooling time prior to pressurization. Flow visualizations indicate that for higher temperatures, and long cooling times, exists a weaker gel strength and failure occurs near the centerline of the pipe. Lower temperatures and long cooling times result in the breakdown of the gel at the pipe wall. Shorter cooling times result in a weak centerline gel strength, and results in gel failure near the centerline of the pipe. Pressure and temperature data were acquired at seven locations along the length of the test section, and these data were correlated to the velocity field, measured using Particle Image Velocimetry. Combined with rheology measurements, these data, allowed for shear stress estimates to be made. For the parameter ranges explored, the results exhibit three different failure modes, each associated with a different set of initial conditions. A critical temperature existed above which one failure mode was encountered and below which another failure mode was found. A third failure mode was associated with a cross-section that did not have a uniform radial temperature profile.

Failure Prediction of Flip Chip Packages Using Finite Element Technique

2002 ◽  
Author(s):  
Abm Hasan ◽  
H. Mahfuz ◽  
M. Saha ◽  
S. Jeelani
Keyword(s):  
Finite Element ◽  
Flip Chip ◽  
Thermal Loading ◽  
Failure Modes ◽  
Element Model ◽  
Thermally Induced ◽  
Operational Life ◽  
Flip Chip Assembly ◽  
The Individual ◽  
Element Technique

Flip-chip electronic package undergoes thermal loading during its curing process and operational life. Due to the thermal expansion coefficient (CTE) mismatch of various components, the flip-chip assembly experiences various types of thermally induced stresses and strains. Experimental measurement of these stresses and strains is extremely tedious and rigorous due to the physical limitations in the dimensions of the flip-chip assembly. While experiments provide accurate assessment of stresses and strains at certain locations, a parallel finite element (FE) analysis and analytical study can complementarily determine the displacement, strain and stress fields over the entire region of the flip-chip assembly. Such combination of experimental, finite element and analytical studies are ideal to yield a successful stress analysis of the flip-chip assembly under the various loading conditions. In this study, a two-dimensional finite element model of the flip-chip consisting of the silicon chip, underfill, solder ball, copper pad, solder mask and substrate has been developed. Various stress components under thermal loading condition ranging from −40°C to 150°C have been determined using both the finite element and analytical methods. Stresses such as (σ11, σ12, ε12 etc. are extracted and analyzed for the individual components as well as the entire assembly, and the weakest positions of the flip-chip have been discovered. Detailed description of FE modeling is presented and the different failure modes of chip assembly are discussed.

Finite Element Analysis of Local Inelastic Strain Based on Stress Redistribution Locus

2008 ◽  
Author(s):  
Shunji Kataoka ◽  
Takuya Sato
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Thermal Loading ◽  
Failure Modes ◽  
Elevated Temperatures ◽  
Pressure Vessels ◽  
Stress Redistribution ◽  
Strain Diagram ◽  
Element Analysis ◽  
Inelastic Analysis

Creep-fatigue damage is one of the dominant failure modes for pressure vessels and piping used at elevated temperatures. In the design of these components the inelastic behavior should be estimated accurately. An inelastic finite element analysis is sometimes employed to predict the creep behavior. However, this analysis needs complicated procedures and many data that depend on the material. Therefore the design is often based on a simplified inelastic analysis based on the elastic analysis result, as described in current design codes. A new, simplified method, named, Stress Redistribution Locus (SRL) method, was proposed in order to simplify the analysis procedure and obtain reasonable results. This method utilizes a unique estimation curve in a normalized stress-strain diagram which can be drawn regardless of the magnitude of thermal loading and constitutive equations of the materials. However, the mechanism of SRL has not been fully investigated. This paper presents results of the parametric inelastic finite element analyses performed in order to investigate the mechanism of SRL around a structural discontinuity, like a shell-skirt intersection, subjected to combined secondary bending stress and peak stress. This investigation showed that SRL comprises a redistribution of the peak and secondary stress components and that although these two components exhibit independent redistribution behavior, they are related to each other.

Experimental investigation on the bending and buckling behavior of bio-based core innovative sandwich panels

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Abdelmadjid Si Salem ◽  
Fatma Taouche-Kkheloui ◽  
Kamal Ait Tahar
Keyword(s):  
Experimental Investigation ◽  
Failure Modes ◽  
Raw Materials ◽  
Sandwich Panels ◽  
Test Results ◽  
Content Type ◽  
Reinforced Polymer ◽  
Buckling Behavior ◽  
Experimental Values ◽  
Original Information

PurposeThe present study aims to experimentally investigate the flexural and buckling performances of novel sandwich panels manufactured with sawdust-based modified mortar core and both polypropylene and reinforced polymer plates as skins.Design/methodology/approachThe experimental investigation includes two main steps, characterization tests were firstly carried out in order to identify the laws behavior of the constitutive raw materials. The second one investigates 42 sandwich panels tested under three-points bending and buckling according to standard norms.FindingsThe emphasized test results in terms of bearing capacity; buckling strength, ductility, and failure mechanisms confirm that the overall and observed behavior of tested eco-friendly panels was in general satisfactory compared with experimental values reported in the literature. Indeed, the failure modes under bending and buckling conditions were summarized as shear/crimping failure of the sawdust-based mortar core without debonding of the core–skins interface.Originality/valueThe paper provides original information about the development of novel sandwich panels with a bio-based core and polymer skins for construction usage as interior partitioning walls.

Lab-scale evaluations on formation of products of incomplete combustion in hazardous waste incineration: influence of process variables

1997 ◽  
Vol 36 (11) ◽  
pp. 219-226 ◽  
Author(s):  
G. Mascolo ◽  
L. Spinosa ◽  
V. Lotito ◽  
G. Mininni ◽  
G. Bagnuolo
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Waste Incineration ◽  
Process Variables ◽  
Thermal Failure ◽  
Process Failure ◽  
Toxic Organics ◽  
Laboratory Investigations ◽  
Hazardous Waste Incineration ◽  
Products Of Incomplete Combustion

Laboratory investigations have been carried out to study the influence of process failure modes on organics emission during the incineration of hazardous sludge. The thermal, temporal and fuel-oxidant mixing failure modes were tested. They were simulated by holding the first combustion temperature at 400°C and varying the after-burning one between 600 and 1100°C, the after-burning residence time between 1 and 3 s and the excess air between 30 and 160%. Results showed that the thermal failure mode is the most important factor controlling the number and concentration of emitted organics leading to the formation of over 70 compounds at after-burning temperature of 600°C. At higher after-burning temperatures emissions are controlled by the fuel-oxidant mixing failure mode and, only when the after-burning is 800°C and the oxygen is 160% over the stoichiometric value, by the temporal failure mode. Based on results obtained some suggestions for reducing emissions of toxic organics in full-scale incinerators are given.

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