Upgrading of the recording system of complex loading testing machine

2021 ◽  
Vol 87 (2) ◽  
pp. 65-71
Author(s):  
V. A. Galiaskarov ◽  
F. F. Adilov ◽  
R. A. Abirov
Keyword(s):  
Tensile Force ◽  
Testing Machine ◽  
Experimental Studies ◽  
Complex Loading ◽  
Recording System ◽  
Electric Signal ◽  
Structural Elements ◽  
Axial Tensile ◽  
Properties Of Materials ◽  
Tubular Specimens

The effectiveness of experimental studies of the mechanical properties of materials and the reliability of the results obtained are determined by the technical level of testing machines. The stress-strain state of the object is monitored using recording sensors. The reading accuracy for the existing CL unit is 8%. However, this accuracy appeared insufficient when studying the developed plastic deformations. The problem of insufficient accuracy is partially related to the outdated recording system of the experimental setup, both when taking the results of the experiments and when managing the experiment. Getting of the reliable data upon complex loading is necessary to identify the reserves of the bearing capacity of structural elements in conditions of multi-parameter loading. All the experiments on a CL testing machine were carried out at room temperature. An additional amplifier of the electric signal of the strain gauge sensor was introduced to improve the accuracy of the readings of the recording system. The results of modernizing the recording system of the CL testing machine intended for static isothermal tests of tubular specimens are presented. The testing machine provides testing of the samples under axial tensile force and torque.

scholarly journals Experimental verification of the isotropy postulate at deformation of steel 45 along orthogonal curvilinear trajectories of constant curvature

2021 ◽  
pp. 86-94
Author(s):  
Вадим Иванович Гультяев ◽  
Андрей Алексеевич Алексеев ◽  
Иван Александрович Саврасов ◽  
Валерий Владимирович Гараников
Keyword(s):  
Experimental Data ◽  
Constant Curvature ◽  
Testing Machine ◽  
Experimental Studies ◽  
Machine Loading ◽  
Combined Action ◽  
Thin Walled ◽  
Strain Space ◽  
Complex Trajectories ◽  
Tubular Specimens

Представлены результаты экспериментальных исследований по проверке достоверности одного из основных законов пластичности - постулата изотропии А.А. Ильюшина в условиях ортогональных сложных нагружений по криволинейным окружным траекториям постоянной кривизны. Экспериментальные исследования выполнены на тонкостенных трубчатых образцах из материала сталь 45 на автоматизированном расчетно-экспериментальном комплексе СН-ЭВМ. Программы нагружения трубчатых образцов задавались в девиаторном пространстве деформаций А.А. Ильюшина при одновременном комбинированном действии на образец растяжения-сжатия и кручения. В экспериментах реализовано четыре траектории деформирования, представляющие собой окружности, начинающиеся из начала координат. Установлено, что для реализованных сложных траекторий постоянной кривизны постулат изотропии выполняется как по скалярным, так и векторным свойствам. The results of experimental studies on validation Ilyushin’s isotropy postulate under the conditions of orthogonal complex loads along curvilinear trajectories of constant curvature. Experimental studies were carried out on thin-walled tubular specimens made of steel 45 on SN-EVM testing machine. Loading programs for tubular specimens were set in the deviatorial strain space of A.A. Ilyushin under the combined action of tension-compression and torsion on the specimens. Experimental data are obtained for four strain trajectories, which are circles starting from the origin. It is found that for the realized complex trajectories of constant curvature the isotropy postulate is fulfilled in terms of scalar and vector properties.

Crack Growth Orientation in Two Structural Materials under Multiaxial Fatigue Loading

2008 ◽  
Vol 587-588 ◽  
pp. 892-897
Author(s):  
Luís G. Reis ◽  
Bin Li ◽  
Manuel de Freitas
Keyword(s):  
Testing Machine ◽  
Experimental Studies ◽  
Complex Loading ◽  
Fatigue Loading ◽  
Structural Materials ◽  
Optical Microscope ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Loading Path ◽  
Biaxial Testing

In real engineering components and structures, many accidental failures are due to unexpected or additional loadings, such as additional bending or torsion, etc. Therefore, it has attracted more research attentions to study the mechanical behavior of materials under complex loading conditions. Two typical structural materials are studied and compared in this paper: AISI 303 stainless steel and 6060-T5 Aluminum alloy. The objective is to study the effects of multiaxial loading paths on the crack initiation and orientation of the two materials studied. Fatigue tests were conducted in a biaxial testing machine. Fractographic analyses of the fracture surface were carried out by optical microscope and SEM approaches. In addition to the experimental studies, theoretical predictions of the damage plane were made using critical plane approaches. Comparisons of the predicted orientation of the damage plane with the experimental observations are shown. The applicability of the multiaxial fatigue criteria for the two materials is discussed. It was shown that the two materials studied have different crack orientations under the same loading path. This observation appears to show that the applicability of the fatigue models is dependent on the material type and multiaxial microstructure characteristics.

scholarly journals Determination of durability of samples modeling the MS-21 fuselage longitudinal and cross joints

2020 ◽  
Vol 23 (3) ◽  
pp. 29-38
Author(s):  
V. K. Harina
Keyword(s):  
Fatigue Failure ◽  
Theoretical Calculations ◽  
Experimental Studies ◽  
Complex Loading ◽  
Operating Conditions ◽  
Test Time ◽  
Structural Elements ◽  
Structural Element ◽  
Operational Load ◽  
Operational Life

Aircraft airworthiness maintenance is carried out by a number of measures guaranteeing safe operation. TsAGI, SibNIIA, GosNIIGA and other organizations with a highly-efficient laboratory base conduct tests and studies of structures and structural elements to determine or extend the operational life in stages. The tests require the capability to recreate complex loading spectra and they can be lengthy and expensive. One of the main problems encountered during testing is its forcing. Forcing reduces the test time while maintaining the equivalence of the fatigue damage and structural failure accumulation mechanisms under real and model loading. For every stage, the operational life limit and durability, guaranteeing flight safety, are determined on the basis of laboratory tests, operation tests and prediction of expected operating conditions. At every stage, information about the emerging defects is accumulated, additional tests are carried out and technical measures, determining the aircraft structure or structural elements operational life and durability, are developed, and design, manufacture, maintenance and repair deficiencies are identified. One of the key issues is the fracture mechanics, which the assessment of the aircraft structures survivability is based on. The fatigue failure mechanism depends on many factors: operational load or its model; stress condition that occurs during testing; the material, which the structural elements are made of. Fatigue failure begins with the microcracks in the structural element weakened area. Under the loads action, often being a random process, the cracks propagation is quite intense and it leads to the destruction of the structure. To determine the durability of the samples, modeling the MS-21 fuselage longitudinal and cross joints, theoretical calculations and experimental studies were carried out, and it allowed to judge about the compliance of the results obtained by the loaded hole.

Investigation of Bioabsorbable Screw Usage for Longbone Fracture Repair in the Horse: Biomechanical Features

1993 ◽  
Vol 06 (01) ◽  
pp. 42-46 ◽  
Author(s):  
T. C. Hearn ◽  
M. Arighi ◽  
J. R. Field
Keyword(s):  
Tensile Force ◽  
Testing Machine ◽  
Fracture Repair ◽  
Materials Testing ◽  
Bone Material ◽  
Bioabsorbable Screw ◽  
Axial Tensile ◽  
Metacarpal Bones ◽  
Significant Difference ◽  
Biomechanical Features

SummaryThe purpose of the study was to compare the biomechanical features of bioabsorbable, self-reinforced polyL-lactic acid (SR-PLLA) and stainless steel 4.5 mm ASIF screws. Paired extraction tests were conducted in matched third metacarpal bones and in a synthetic bone material composed of polyurethane foam. The tests were accomplished using a servohydraulic materials testing machine. From these tests the maximum value of tensile force, achieved during extraction, was recorded as the screw “holding strength‘.Comparison of holding strengths in horse cadaver bones revealed a significant difference (p = 0.0002) between screw types. The axial tensile strength of the SR-PLLA screws (878 Newtons) was much lower than that achieved by the ASIF screws (8513 N). Subsequent testing in synthetic material again reflected significant differences (p <0.0001) between the screw types. The results may be accounted for by differences in the thread-to-core ratio between the screw types. Other factors, such as elastic deformation of the bioabsorbable screw, may also contribute through differences in the mechanical interface between screw and media.

Research of the Mechanical Properties of the Filament from the Percentage of Filling when Prototyping Machine Parts

2021 ◽  
Vol 410 ◽  
pp. 617-623
Author(s):  
Elena N. Gryadynova ◽  
Andrey V. Gorin ◽  
Alexey Yu. Rodichev
Keyword(s):  
Tensile Strength ◽  
Tensile Testing ◽  
Testing Machine ◽  
Experimental Studies ◽  
Relative Deformation ◽  
Strain Diagram ◽  
Experimental Sample ◽  
Tensile Testing Machine ◽  
Machine Parts ◽  
Fisher’S Criterion

The article contains the analysis of thermoplastics used in prototyping machine parts. We used several types of experimental samples with different filling percentages. The equipment on which the experimental studies were carried out is shown. During the experiment, a specialized tensile testing machine was used. The experimental samples were installed in the developed centering device. Normal conditions were observed during the tests. The results of an experimental tensile study of PLA-plastic specimens are presented. The typical stress-strain diagram of an experimental sample is described, which describes the dependence of stress on relative deformation. An equation of the linear dependence of the tensile strength on the percentage of filament filling has been compiled, which makes it possible to determine the tensile strength of the product at any percentage of the filling of the plastic filament. The assessment is adequately verified by Fisher's criterion. Recommendations for filament filling in prototyping machine parts are given.

Numerical Investigation of Ductile Fracture in Pipelines Under Complex Loading Using a Phenomenological Damage Model

2021 ◽  
Author(s):  
Iago S. Santos ◽  
Diego F. B. Sarzosa
Keyword(s):  
Ductile Fracture ◽  
Mechanical Response ◽  
Numerical Study ◽  
Damage Model ◽  
Stress Triaxiality ◽  
Numerical Procedure ◽  
Complex Loading ◽  
Experimental Tests ◽  
Compact Tension ◽  
Axial Tensile

Abstract This paper presents a numerical study on pipes ductile fracture mechanical response using a phenomenological computational damage model. The damage is controlled by an initiation criterion dependent on the stress triaxiality and the Lode angle parameter, and a post-initiation damage law to eliminate each finite element from the mesh. Experimental tests were carried out to calibrate the elastoplastic response, damage parameters and validate the FEM models. The tested geometries were round bars having smooth and notched cross-section, flat notched specimens under axial tensile loads, and fracture toughness tests in deeply cracked bending specimens SE(B) and compact tension samples C(T). The calibrated numerical procedure was applied to execute a parametric study in pipes with circumferential surface cracks subjected to tensile and internal pressure loads simultaneously. The effects of the variation of geometric parameters and the load applications on the pipes strain capacity were investigated. The influence of longitudinal misalignment between adjacent pipes was also investigated.

Stress-Strain Curves for Oxygen-Free High Conductivity Copper at Shear Strain Rates of up to 103s-1

1970 ◽  
Vol 185 (1) ◽  
pp. 1149-1158 ◽  
Author(s):  
K. Bitans ◽  
P. W. Whitton
Keyword(s):  
Shear Strain ◽  
Testing Machine ◽  
Shear Bands ◽  
Strain Curve ◽  
Strain Rates ◽  
Adiabatic Shear Bands ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
The Given ◽  
Tubular Specimens

Shear stress-shear strain curves for o.f.h.c. copper at room temperature have been obtained at constant shear strain rates in the range 1 to 103s-1, using thin walled tubular specimens in a flywheel type torsion testing machine. Results show that, for a given value of strain, the stress decreases when the rate of strain is increased. Moreover, the elastic portion of the stress-strain curve tends to disappear as the rate of strain is increased. It is postulated that these effects are due to the formation of adiabatic shear bands in the material when the given rate of strain is impressed rapidly enough. A special feature of the design of the testing machine used is the rapid application of the chosen strain rate.

scholarly journals МОДЕЛЮВАННЯ ПРОЦЕСУ ТЕРТЯ В ТЕКСТИЛЬНИХ МАТЕРІАЛАХ

2020 ◽  
Vol 144 (2) ◽  
pp. 45-53
Author(s):  
Н. П. Супрун ◽  
М. Л. Рябчиков ◽  
І. О. Іванов
Keyword(s):  
Mechanical Properties ◽  
Coefficient Of Friction ◽  
Textile Material ◽  
Structural Elements ◽  
Friction Process ◽  
Textile Materials ◽  
Factors Influencing ◽  
The Coefficient Of Friction ◽  
Properties Of Materials ◽  
Main Factors

Create a model for determining the coefficient of friction of textile materials to identify the main factors influencing the process of friction, taking into account the structural and mechanical properties of materials. Modeling of friction process in textile materials as a combination of adhesive and elastic phenomena. Roughness of solid bodies and the main parameters of roughness, such as the height of micro-irregularities, their pitch, sharpening, etc. described in many standards and scientific papers. However, the modeling of the friction process in such systems is very complicated due to the irregularity of distribution of microroughness. The analysis of literature data showed that the surface roughness of textile materials is an important and effective factor in predicting the tactile properties of products for various purposes. Estimation of surface roughness is usually carried out using subjective and objective methods, and the latter can be contact and non-contact. The paper develops a model for determining the coefficient of friction of textile materials to identify the main factors influencing the friction process, taking into account the structural and mechanical properties of materials. Friction force is presented as a combination of two main factors. The first is the elastic resistance to deformation, the second is the adhesive resistance to compression of the structural elements of the material. The main parameters influencing the coefficient of friction of textile fabrics - modulus of elasticity of structural elements, their geometrical parameters - surface density of textile material, linear density of structural elements are established. The obtained results allow to qualitatively predict the friction forces of a textile material with known parameters of its structural elements, as well as to normalize these parameters to create materials with specified friction indices. The obtained results make it possible to select the threads that form the textile material, according to the values of the modulus of elasticity, thickness, location density to ensure the minimum friction force.

Effect of Loading Rate on Tensile Properties of Automotive Steel Sheet

2013 ◽  
Vol 690-693 ◽  
pp. 211-217
Author(s):  
Jin Gui Qin ◽  
Fang Yun Lu ◽  
Yu Liang Lin ◽  
Xue Jun Wen
Keyword(s):  
Strain Rate ◽  
Testing Machine ◽  
Structural Response ◽  
Tensile Tests ◽  
Dynamic Tests ◽  
Static Tests ◽  
Split Hopkinson Tensile Bar ◽  
Axial Tensile ◽  
Static Tensile ◽  
Cook Model

Results of uni-axial tensile loading of three automotive steels at different strain rates (0.0011–3200s-1) are reported here. Quasi-static tensile tests were performed under the strain rate of 1.1×10-3 s-1 using an electromechanical universal testing machine, whereas dynamic tests were carried out under the strain rate in the range of 1100 to 3200 s-1 using a Split Hopkinson Tensile Bar apparatus. Based on the experimental results, the material parameters of widely used Johnson–Cook model which described the strain rate and temperature-dependent of mechanical behaviour were determined. The experiments show that strain-rate hardening is superior to thermal softening: yield stresses, tensile strength, deformation, and energy dissipation increase with the strain rate from quasi-static tests to dynamic tests. The Johnson–Cook model can describe the behaviour of these steels and provides the opportunity to study the material and structural response.

Experimental Evaluation of Tensile Forces in Short Steel Rods

2015 ◽  
Vol 732 ◽  
pp. 333-336 ◽  
Author(s):  
Michal Polak ◽  
Tomáš Plachy
Keyword(s):  
Tensile Force ◽  
String Model ◽  
Beam Model ◽  
Building Structures ◽  
Structural Elements ◽  
Frequency Method ◽  
Natural Modes ◽  
Tensile Forces ◽  
Torsion Springs ◽  
Fixed Beam

There are a lot of structures in building and civil engineering where the significant structural elements are loaded by large tensile forces (e.g. tension bars of building structures). In many practical cases it is important to know the actual value of tensile forces in tensile structural elements for assessment of their reliability. The four experimental techniques are used for determination of tensile forces in practice most often. The vibration frequency method, which is one of them, is very suitable for experiments done only one time or sometimes, especially in cases when the examined structural elements are already activated and the application of an experimental method is necessary in this situation. The experiment described in this paper was focused on the tensile force determination in steel rods, which were very short and relatively stiff. The evaluated tensile forces of the investigated short steel rods were affected by a significant error when only the simplest models (the string model, the simply supported beam and the fixed beam) and measured natural frequencies were applied. In order to precise the determined tensile forces, the theoretical beam model supported by simple supports with torsion springs (“the elastically fixed beam”) and the measured natural modes of the rods had to be necessarily taken into account.

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