scholarly journals Experimental and Numerical Studies of Low-Profile, Triangular Grid-Stiffened Plates Subjected to Shear Load in the Post-Critical States of Deformation

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3699 ◽  
Author(s):  
Łukasz Święch
Keyword(s):  
Pure Shear ◽  
Experimental Tests ◽  
Production Costs ◽  
Image Correlation ◽  
Experimental Investigations ◽  
Triangular Grid ◽  
Reference Structure ◽  
Shear Load ◽  
Low Profile ◽  
Thin Walled

Constant developments in manufacturing technology have made it possible to introduce integrally stiffened elements into load-bearing, thin-walled structures. The application of thin-walled elements with integral stiffeners potentially increases buckling and critical loads to maintain the mass of the structure and lower production costs. This paper presents the results of experimental investigations and numerical Finite Element Modelling (FEM) analyses of low-profile, isosceles grid stiffened, aluminium alloy plates subjected to pure shear load. Conducted research included analysing buckling and post-buckling states of deformation, taking into account both geometrical and physical nonlinear effects. Use of the Digital Image Correlation (DIC) system during the experimental tests created representative equilibrium pathways and recorded displacement field distributions over the plate surface. The model was initially validated against the experimental results. The results for the stiffened plate were compared to the reference structure in the form of a smooth plate with equivalent mass. Comparative analyses included examining the displacement fields and stress efforts over the plates. The stiffening configuration under examination increased the critical buckling load by 300% in comparison to the unstiffened structure with the same mass. Obtained results also indicate potential problems with areas of concentrated stress in the case of an incorrect geometry design near to the boundary conditions.

scholarly journals Experimental Investigations of Impact Damage Influence on Behavior of Thin-Walled Composite Beam Subjected to Pure Bending

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1127 ◽  
Author(s):  
Tomasz Kubiak ◽  
Lukasz Borkowski ◽  
Nina Wiacek
Keyword(s):  
Impact Damage ◽  
Full Range ◽  
Image Correlation ◽  
Bending Test ◽  
Beam Deflection ◽  
Experimental Investigations ◽  
Pure Bending ◽  
Channel Section ◽  
Thin Walled ◽  
The Impact

The paper deals with buckling, postbuckling, and failure of pre-damaged channel section beam subjected to pure bending. The channel section beams made of eight-layered GFRP laminate with different symmetrical layups have been considered. The specimens with initially pre-damaged web or flange were investigated to access the influence of impact damage on work of thin-walled structure in the full range of load till failure. The bending tests of initially pre-damage beams have been performed on a universal tensile machine with especially designed grips. The digital image correlation system allowing to follow the beam deflection have been employed. The experimentally obtained results are presented in graphs presenting load-deflection or load vs. angle of rotation relations and in photos presenting impact damages areas before and after bending test. The results show that the impact pre-damages have no significant influence on the work of channel section beams.

Inverse Identification of CDM Model Parameters for DP1000 Steel Sheets Using a Hybrid Experimental-Numerical Methodology Spanning Various Stress Triaxiality Ratios

2013 ◽  
Vol 554-557 ◽  
pp. 2103-2110 ◽  
Author(s):  
Zhen Ming Yue ◽  
Celal Soyarslan ◽  
Houssem Badreddine ◽  
Khemais Saanouni ◽  
A. Erman Tekkaya
Keyword(s):  
Constitutive Model ◽  
Pure Shear ◽  
Stress Triaxiality ◽  
Experimental Tests ◽  
Image Correlation ◽  
Material Surface ◽  
Model Parameters ◽  
Mixed Hardening ◽  
Steel Sheets ◽  
Strain Paths

A hybrid experimental-numerical methodology is presented for the identification of the model parameters regarding a mixed hardening anisotropic finite plasticity fully coupled with isotropic ductile damage in which the micro-crack closure effect is given account for, for steel sheets made of DP1000. The experimental tests involve tensile tests with smooth and pre-notched specimens and shear tests with specimen morphologies recently proposed by D.R. Shouler, J.M. Allwood (Design and use of a novel sample design for formability testing in pure shear, Journal of Materials Processing Technology, Volume 210, Issue 10, 1 July 2010, Pages 1304-1313). These tests cover stress triaxiality ratios lying between 0 (pure shear) and 1/√3 (plane strain). To neutralize machine stiffness effects displacements of the chosen material surface pixels are kept track of using the digital image correlation system ARAMIS, where recorded inputs are synchronized with force measurements. On the numerical part, developed constitutive model is implemented as user defined material subroutine, VUMAT, for ABAQUS/Explicit. FE models for the test cases are built using 3D brick elements (rather than thin shells) and devising developed VUMAT for the constitutive model, model parameters are identified using an inverse parameter identification procedure where the objective function relies on the difference of experimentally observed-numerically predicted forces for the selected pixel displacements. The validity of the material model and transferability of its parameters are tested using tests involving complex strain paths.

scholarly journals Numerical and experimental analyses of non-energy absorbing lighting poles

2018 ◽  
Vol 38 (1) ◽  
pp. 71-74
Author(s):  
Tomasz Ireneusz Jedliński ◽  
Jacek Buśkiewicz ◽  
Paweł Fritzkowski
Keyword(s):  
Numerical Analysis ◽  
Kinetic Energy ◽  
Experimental Tests ◽  
Production Costs ◽  
Test Track ◽  
Impact Speed ◽  
Safety Requirements ◽  
Thin Walled ◽  
Experimental Analyses ◽  
Energy Absorbing

Abstract Apart from the strength requirements, modern lighting pole designs have to meet a number of safety requirements in the event of collisions. The paper compares the experimental tests performed at the collision test track according to EN 12767 with the results of the numerical analysis carried out in Ansys LS-DYNA. The objective of the work is to prepare a new structure of a thin-walled lighting pole of steel which minimizes absorption of the kinetic energy of the vehicle and, simultaneously, its production costs are comparable to those of a standard pole. The tests were carried out at an impact speed of 100 km/h.

scholarly journals Effect of Bottom Geometry on the Natural Sloshing Motion of Water Inside Tanks: An Experimental Analysis

2021 ◽  
Vol 11 (2) ◽  
pp. 605
Author(s):  
Antonio Agresta ◽  
Nicola Cavalagli ◽  
Chiara Biscarini ◽  
Filippo Ubertini
Keyword(s):  
Energy Dissipation ◽  
Water Depth ◽  
Shear Force ◽  
Experimental Tests ◽  
Shear Load ◽  
Damping Properties ◽  
Base Shear ◽  
Structure Interaction ◽  
Sloshing Phenomenon ◽  
Key Aspects

The present work aims at understanding and modelling some key aspects of the sloshing phenomenon, related to the motion of water inside a container and its effects on the substructure. In particular, the attention is focused on the effects of bottom shapes (flat, sloped and circular) and water depth ratio on the natural sloshing frequencies and damping properties of the inner fluid. To this aim, a series of experimental tests has been carried out on tanks characterised by different bottom shapes installed over a sliding table equipped with a shear load cell for the measurement of the dynamic base shear force. The results are useful for optimising the geometric characteristics of the tank and the fluid mass in order to obtain enhanced energy dissipation performances by exploiting fluid–structure interaction effects.

scholarly journals Increase in Total Elongation Caused by Pure Shear Deformation in Ultra-Fine-Grained Cu Processed by Equal-Channel Angular Pressing

Metals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 654
Author(s):  
Ryosuke Matsutani ◽  
Nobuo Nakada ◽  
Susumu Onaka
Keyword(s):  
Shear Deformation ◽  
Equal Channel Angular Pressing ◽  
Pure Shear ◽  
Three Dimensional ◽  
Tensile Tests ◽  
Total Elongation ◽  
Local Deformation ◽  
Image Correlation ◽  
Fine Grained ◽  
Angular Pressing

Ultra-fine-grained (UFG) Cu shows little total elongation in tensile tests because simple shear deformation is concentrated in narrow regions during the initial stage of plastic deformation. Here, we attempted to improve the total elongation of UFG Cu obtained by equal-channel angular pressing. By making shallow dents on the side surfaces of the plate-like specimens, this induced pure shear deformation and increased their total elongation. During the tensile tests, we observed the overall and local deformation of the dented and undented UFG Cu specimens. Using three-dimensional digital image correlation, we found that the dented specimens showed suppression of thickness reduction and delay in fracture by enhancement of pure shear deformation. However, the dented and undented specimens had the same ultimate tensile strength. These results provide us a new concept to increase total elongation of UFG materials.

scholarly journals A Numerical Strategy to Identify the FSW Process Optimal Parameters of a Butt-Welded Joint of Quasi-Pure Copper Plates: Modelling and Experimental Validation

2021 ◽  
Author(s):  
Monica Daniela IORDACHE ◽  
Claudiu BADULESCU ◽  
Malick DIAKHATE ◽  
Adrian CONSTANTIN ◽  
Eduard Laurentiu NITU ◽  
...  
Keyword(s):  
Welded Joint ◽  
Pure Copper ◽  
Correlation Method ◽  
Image Correlation ◽  
Experimental Investigations ◽  
Optimal Parameters ◽  
Friction Stir ◽  
Mass Scaling ◽  
Surface Response ◽  
Fsw Parameters

Abstract Determining the optimal parameters of the Friction Stir Welding (FSW) process, which are suitable for a given joint configuration, remains a great challenge and is often achieved through extremely time-consuming and costly experimental investigations. The present paper aims to propose a strategy for the identification of the optimal parameters for a butt-welded joint of 3-mm thick quasi-pure copper plates. This strategy is based on FEM (finite elements method) simulations and the optimal temperature that is supposedly known. A robust and efficient finite element model that is based on the Coupled Eulerian-Lagrangian (CEL) approach has been adopted and a temperature-dependent friction coefficient has been used. Besides, the mass scaling technique has been used to significantly reduce the simulation time. The thermo-mechanical behavior of the butt-welded joint was modeled using a Johnson-Cook plasticity model that was identified through lab tests at different temperatures. The results of the parametric study help to define the numerical surface response, and based on this latter one can found the optimal parameters, advancing (υa) and rotational (υr) speeds, of the FSW process. This numerical surface response has been validated with good agreement between the numerical prediction of the model and the experimental results. Furthermore, experimental investigations involving x-ray radiography, digital image correlation method, and fracture surface analysis have helped a better understanding of the effects of FSW parameters on the welded joint quality.

scholarly journals Stiffness of Concrete-Filled Thin-Walled Steel Tubular Slender Columns

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Alireza Bahrami ◽  
Ali Mahmoudi Kouhi
Keyword(s):  
Uniform Distribution ◽  
Experimental Tests ◽  
Simulation Method ◽  
Steel Tube ◽  
Initial Stiffness ◽  
Cross Sectional ◽  
Circular Column ◽  
Finite Element Software ◽  
Thin Walled ◽  
Slender Columns

Abstract Concrete-filled thin-walled steel tubular slender columns are studied in this paper to evaluate their stiffness. The slender columns have various steel tube thicknesses, length/diameter (width) ratios, and concrete compressive strengths. The columns are loaded by axial and eccentric loads. Two experimental tests of the slender and stub columns are described. Also, the finite element software ABAQUS is utilised to simulate and analyse the columns. The tested columns are simulated taking into account all their features in the tests to verify the simulation of the columns. The simulation results are compared with the tests results which reveal that good agreements exist between them. Thus, the proposed simulation method of the columns is verified. In order to assess the stiffness of the columns under different conditions, various load eccentricities (0 mm, 25 mm, and 50 mm), cross-sectional configurations (circular, rectangular, and square), and steel tube thicknesses (2 mm, 3.35 mm, and 5 mm) are adopted for the developed columns. The columns are simulated and analysed based on the verified simulation method considering the mentioned conditions. As a conclusion, the stiffness of the columns is generally reduced by the increase of the load eccentricity from 0 mm to 25 mm and 50 mm. Further, more uniform distribution of the stiffness is witnessed for the columns with lower eccentricities. In addition, the enhancement of the load eccentricity increased the reduction slope of the stiffness graph for the columns. Although the initial stiffness of the circular column is slightly lower than the rectangular and square columns, the stiffness has more uniform distribution which is preferred. Larger stiffness is achieved for the columns by increasing the steel tube thickness from 2 mm to 3.35 mm and 5 mm.

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