Development of a Pendulum-Type Dynamic Tear-Test Machine

Overall profitability is a major goal in successful prune production and a major component in any prune management system. Large prune crops in 1996 and 1997 have stimulated considerable interest in undersize fruit. Undersize prunes currently have marginal value and may represent a net loss because of costs to haul, dry, and to market order payments on low value prunes. One technique to control delivery size is to field size at harvest. Field sizing involves installing size-sorting devices on harvesters, which allow small prunes to fall out while valuable fruit is collected. Field sizing is considered a “risky” strategy because of the potential to remove prunes with economic value. During the 1997 harvest, 21 infield harvest sizing evaluations were made in prune orchards throughout Tehama county. The first evaluation occurred on 12 Aug. 1997, at the start of prune harvest. The final evaluation was done on 5 Sept. 1997, at the tail end of harvest. The objective was to sample throughout the harvest period to test field sizing under various sugar, size, and fruit pressure scenarios. The test machine was 1-inch bar sizer. Of the 21 sample dates, undersize fruit was clearly not marketable in 20 of the 21 samples. Discarded fruit averaged 133 dry count per pound. Only one sample out of 21 may have had market value at 86 dry count per pound. Although small in size, these prunes had very high sugar content contributing to their dry weight. In this evaluation, a 1-inch bar sizer did a good job of separating fruit with and without market value under the 1997 price schedule. As harvest date becomes later and soluble solids increase, the chances of sorting out marketable prunes also increases.

Download Full-text

Hopkinson rod test results and constitutive description of TRIP780 steel resistance spot welding material

Open Physics ◽

10.1515/phys-2020-0206 ◽

2020 ◽

Vol 18 (1) ◽

pp. 961-967

Author(s):

Xiaomin Li ◽

Jianrong Zhang

Keyword(s):

Spot Welding ◽

Steel Strip ◽

Strain Curve ◽

Test Machine ◽

Strain Rates ◽

Test Results ◽

Welding Material ◽

Static Tensile ◽

Split Hopkinson ◽

Brittle Fractures

Abstract A quasi-static tensile test was performed on a 1.4 mm-thick TRIP780 steel strip with welding points. An MTS810 material test machine was used in the test, and a Split Hopkinson tension bar device was used in performing impact stretch loading at different strain rates. The dynamic tensile stress–strain curve of the spot welding material with different strain rates was obtained through the finely designed Hopkinson rod test, and the strain rate dependence of a TRIP780 steel spot welding material was discussed. According to the dynamic constitutive equation of the TRIP780 steel spot welding material, the test results were numerically simulated, the constitutive description and test curves were compared, and the simulation results and test results were discussed and analyzed. The fractures of the test recovery specimen were scanned with the scanning electron microscope, and the fracture mechanism of the TRIP780 steel spot welding material was explored by observing the fractures. The surfaces of the fractures surface showed obvious cleavage river patterns, and the evolution process of microcracks was determined and used in characterizing brittle fractures in specimen spot welding sample subjected to dynamic stretch loading.

Download Full-text

Instability analysis of a filament-wound composite tube subjected to compression/bending

Advanced Composites Letters ◽

10.1177/0963693519877417 ◽

2019 ◽

Vol 28 ◽

pp. 096369351987741

Author(s):

Gyula Szabó ◽

Károly Váradi

Keyword(s):

Failure Modes ◽

Slenderness Ratio ◽

Equivalent Stress ◽

Bending Test ◽

Test Machine ◽

Fe Model ◽

Rubber Tube ◽

Nonlinear Buckling ◽

Cross Sectional ◽

Composite Tube

The aim of this study is to investigate the global buckling of a relatively long composite cord–rubber tube subjected to axial compression and its cross-sectional instability due to bending by a macromechanical nonlinear finite element (FE) model (nonlinear buckling analysis). Composite reinforcement layers are modelled as transversely isotropic ones, while elastomer liners are described by a hyperelastic material model that assumes incompressibility. Force–displacement, equivalent strain, equivalent stress results along with oblateness and curvature results for the complete process have been presented. It is justified that bending leads to ovalization of the cross section and results in a loss of the load-carrying capacity of the tube. Strain states in reinforcement layers have been presented, which imply that the probable failure modes of the reinforcement layers are both delamination and yarn-matrix debonding. There is a significant increase in strains due to cross-sectional instability, which proves that the effect of cross-sectional instability on material behaviour of the tube is crucial. A parametric analysis has been performed to investigate the effect of the member slenderness ratio on cross-sectional instability of the composite tube. It shows that Brazier force is inversely proportional to the slenderness ratio. It further shows that higher oblateness parameters occur in case of a lower slenderness ratio and that cross-sectional instability takes place at a lower dimensionless displacement in case of a lower slenderness ratio. FE results have been validated by a compression/bending test experiment conducted on a tensile test machine.

Download Full-text

Heat Treatment Effects on Static and Dynamic Mechanical Properties of Sintered SINT D30 Powder Metal

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.592-593.643 ◽

2013 ◽

Vol 592-593 ◽

pp. 643-646 ◽

Cited By ~ 1

Author(s):

Marko Šori ◽

Tomaž Verlak ◽

Srečko Glodež

Keyword(s):

Mechanical Properties ◽

Complex Geometry ◽

Low Cost ◽

Surface Hardness ◽

Load Ratio ◽

Tensile Tests ◽

Test Machine ◽

Strain Diagram ◽

Powder Metal ◽

Sintered Steel

Low cost, low material waste and good accuracy in components with complex geometry are the main reasons for powder metallurgy to be considered as a promising manufacturing process for the future. Like wrought steel, sintered steel can also be heat treated to increase surface hardness and to improve strength. This paper compares mechanical properties of the hardened sintered steel with the sintered steel of the same powder metal SINT D30. Firstly, the static strength of both samples is determined by quasi-static tensile tests. Results are compared in stress strain diagram and they show that the tensile strength of the hardened sintered steel SINT D30 can surpass 700 MPa. The main focus of this study is however fatigue behaviour of the sintered steel. Both sets of samples are tested on a pulsating test machine with the load ratio of R = 0. The first sample is subjected to a load that corresponds to 90 % of the yield strength and is then gradually lowered to achieve one million stress cycles without breakage. Obtained results are then presented as Wöhler curves and compared in S-N diagram.

Download Full-text

Effects of temperature and impactor nose diameter on the impact behavior of PA6 and PP thermoplastic composites

Journal of Elastomers & Plastics ◽

10.1177/0095244318780509 ◽

2018 ◽

Vol 51 (1) ◽

pp. 64-74 ◽

Cited By ~ 2

Author(s):

Akar Dogan ◽

Yusuf Arman

Keyword(s):

Load Capacity ◽

Testing Machine ◽

Polyamide 6 ◽

Impact Testing ◽

Impact Behavior ◽

Thermoplastic Composites ◽

Test Machine ◽

Effects Of Temperature ◽

Impact Energies ◽

The Impact

In this study, the effects of temperature and impactor nose diameter on the impact behavior of woven glass-reinforced polyamide 6 (PA6) and polypropylene (PP) thermoplastic composites were investigated experimentally. Impact energies are chosen as 10, 30, 50, 70, 90, 110, 130, and 170 J. The thickness of composite materials is 4 mm. Impact tests were performed using a drop weight impact testing machine, CEAST-Fractovis Plus, and the load capacity of test machine is 22 kN. Hemispherical impactor nose diameter of 12, 7, and 20 mm were used as an impactor. The tests are conducted at room temperature (20°C and 75°C). As a result, the PP composites of the same thickness absorbed more energy than PA6 composites. The amount of absorbed energy of PP and PA6 composites decreased with temperature.

Download Full-text

Mechanical Properties of Hypereutectoid Steel with Microduplex (α+θ) Structure Formed by Hot Deformation of Undercooled Austenite

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.246 ◽

2010 ◽

Vol 654-656 ◽

pp. 246-249

Author(s):

Long Fei Li ◽

Wei Chen ◽

Wang Yue Yang ◽

Zu Qing Sun

Keyword(s):

Mechanical Properties ◽

Hot Deformation ◽

Ferrite Matrix ◽

Subsequent Annealing ◽

Test Machine ◽

Compression Tests ◽

Simulation Test ◽

Hypereutectoid Steel ◽

Lamellar Pearlite ◽

Undercooled Austenite

Microstructure evolution and mechanical properties of hypereutectoid steel with the microduplex (α+θ) structures formed by hot deformation of undercooled austenite were investigated by hot uniaxial compression tests in a Gleeble-1500 simulation test machine, and the effects of subsequent annealing and the addition of Al were analyzed. The results indicated that at the beginning of hot deformation of undercooled austenite the formation of proeutectoid cementite was retrained and only lamellar pearlite was produced. With further strain, dynamic spheroidization of pearlite took place, leading to the formation of microduplex (α+θ) structure consisting of ultrafine ferrite matrix and dispersed cementite particles. In comparison with the normal microstructure consisting of lamellar pearlite and proeutectoid cementite, the microduplex (α+θ) structure presented higher strengths with similar ductility. Subsequent annealing could make the microduplex (α+θ) structure more uniform, which demonstrated better balance between strength and ductility. The addition of Al is disadvantageous to the formation of microduplex (α+θ) structure, but can result in the further refinement. With the addition of Al, the strength of microduplex (α+θ) structure was improved and the ductility was not deteriorated markedly.

Download Full-text

Full Scale Fatigue Experiment on Submarine Pipelines

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.633-634.659 ◽

2014 ◽

Vol 633-634 ◽

pp. 659-664 ◽

Cited By ~ 1

Author(s):

Zong Tao Fang ◽

De Yu Tang ◽

Yan Hua Hu ◽

Hu Li Niu

Keyword(s):

Welded Joints ◽

Fatigue Property ◽

Full Scale ◽

Small Scale ◽

Test Machine ◽

Butt Joints ◽

Weld Toe ◽

Small Test ◽

Weld Root ◽

Fatigue Experiment

This paper focus on fatigue problem of submarine pipelines, four points bending full scale fatigue experiment were conducted on X65 pipelines butt joints specimens, utilizing pipeline full scale fatigue test machine developed by CNPC. Meanwhile contrast test was also carried out on small specimens. The results show that the fatigue strength of full scale welded joints is lower than the small scale joints. Owing to having no regard for the influence of residual stress and size effect, the small test would provide dangerous results. The fatigue property of full scale welded joints only meets the requirement of DNV C203 W3 curve, and meets the needs of DNV C203 F3 curve basically while not meet BS 7608 F2 curve’s requirements which relatively demand higher. Weld toe and geometric discontinuous near weld root is the weak point for the whole welded joints.

Download Full-text

Effects of abrasion on mechanical properties of Kevlar KM2-600 and S glass tows

Textile Research Journal ◽

10.1177/0040517518760753 ◽

2018 ◽

Vol 89 (6) ◽

pp. 989-1002

Author(s):

A Abu Obaid ◽

JW Gillespie

Keyword(s):

Mechanical Properties ◽

Abrasion Resistance ◽

Glass Fibers ◽

Fiber Surface ◽

Surface Damage ◽

Contact Length ◽

Test Machine ◽

Tension Level ◽

Micro Cracks ◽

Coating Removal

In this effort, the effects of abrasion on the mechanical properties of Kevlar KM2-600 and two types of S glass tows (AGY S2 and Owens Corning Shield Strand S) are studied. Data was generated from cyclic abrasion tests conducted at a tension level of 8% of failure load at10 mm/s (24 in/min) using a specially developed abrasion test machine. Fit curves for axial modulus and tenacity loss were established as a function of abrasion time/contact length for each tow type. Fiber surface damage and fiber breakage within the tows were identified as the major source of tow property degradation. Based on scanning electron microscopy measurements, glass fibers exhibited surface damage (micro-cracks and sizing/coating removal) that were more extensive in AGY S2 glass fibers. Kevlar KM2 fibers after tow abrasion tests exhibited fibrillation and peeling of broken fibrils from the fiber surface. In all three fibers, surface damage increased at longer abrasion times/friction contact length. Overall, the results indicated that the abrasion resistance is the highest for Kevlar KM2, followed by OCV Shield Strand and AGY S2 glass tows. The sizing material on OCV Shield Strand fibers contributed to the improved abrasion resistance compared to AGY S2.

Download Full-text