Stress intensity and crack displacement for small edge cracks

The weight function method was used to derive stress intensity factors and crack mouth displacement coefficients for small edge cracks (less than 20 percent of the specimen width) in common fracture specimen configurations. Contact stresses due to point application of loads were found to be small but significant for three-point bending and insignificant for four-point bending. The results are compared with available equations and numerical solutions from the literature and with unpublished boundary collocation results

Geometry functions for edge cracks in steel bridge under three- and four- point bending with various span

Fatigue cracks are found during the regular structural inspections. To precisely describe/suggest propagation of fatigue cracks throughout structure and it’s designed service life, the knowledge of geometry functions describing the stress situation in front of the crack tip for relative crack lengths are important. The cracks usually propagate/initiated from the edge or the surface of the structural element, where the maximum value of applied load is achieved. The theoretical model of fatigue crack propagation is based on linear fracture mechanics (Paris law). Steel structural elements are subjected to various bending load (three-, four- point bending and pure bending etc.). The geometry functions for the edge cracks are calculated for various span according to real steel bridge elements and appropriate polynomial functions independent on the distance are proposed for three- and four- point bending load

RANCANG BANGUN ALAT UJI BENDING SISTEM HIDROLIK DAN HASIL PENGUJIAN UNTUK BAHAN UJI BESI COR ( DESIGN OF BENDING HYDRAULIC SYSTEM TEST EQUIPMENT AND MATERIALS TESTING TESTING RESULTS FOR CAST IRON )

Uji lengkung merupakan salah satu jenis pengujian bahan yang dilakukan untuk mengetahui sifat mekanik suatu bahan teknik. Dalam prakteknya masih sedikit para praktisi pengujian bahan yang memperhatikan aspek dan pengaruh variasi dimensi benda uji terhadap data hasil uji lengkung. Untuk itu alat uji bending ini dibuat untuk mempelajari pengaruh variasi dimensi benda uji pada pengujian lengkung. Pengujian dilakukan dengan menggunakan alat uji bending sistem hidrolik dengan dimensi alat 600x75x750 mm. Dan pengujian terhadap bahan uji besi cor dengan tiga variasi dimensi yaitu 50x5x10 mm, 50x4x9 mm dan 50x4x6 mm, dan metode yang digunakan dalam pengujian ini adalah three point bending dan four point bending. Data tekanan dongkrak, simpangan dan waktu penekanan diambil hingga spesimen/benda uji mendapatkan tekanan maksimal dari gaya tekan hidrolik. Hasil pengujian menunjukkan bahwa dimensi benda uji mempengaruhi gaya tekan yang terjadi pada saat pengujian. Semakin kecil dimensi yang di uji maka semakin kecil pula gaya tekan yang di timbulkan. Pada saat melakukan bending test, nilai rata-rata flexural strength yang didapatkan dengan menggunakan metode trhee point bending sebesar 61,69 kg/mm2 dan pada saat melakukan pengujian dengan four point bending sebesar 45,86 kg/mm2. Kata Kunci: Bending test, three point bending, four point bending, flexural strength, dimensi Bending test is one type of material testing conducted to determine the mechanical properties of a material engineering. In practice there are still few practitioners who pay attention to aspects of materials testing and the influence of variations in the dimensions of the specimen to bend test result file. For the bending test equipment is designed to study the effect of variations in the dimensions of the specimen on the test arch. Tests carried out using test equipment with a hydraulic system bending tool dimensions 600x75x750 mm. And testing of test materials of cast iron with three variations of dimensions 50x5x10 mm, mm 50x4x9 and 50x4x6 mm, and the methods used in this test is the three-point bending and four point bending. Pressure data jack, deviation and suppression time taken to specimen / test object get the maximum pressure of the hydraulic press style.Test results show that the dimensions of the specimen affects the compressive force that occurs during testing. The smaller dimensions in the smaller trials also compressive force that caused. At the time of bending test, the average value of flexural strength are obtained using methods trhee point bending at 61.69 kg/mm2 and at the time of testing with a four-point bending at 45.86 kg/mm2. Keywords: Bending test, three-point bending, four point bending,flexural strength, dimensiona

RANCANG BANGUN ALAT UJI BENDING SISTEM HIDROLIK DAN HASIL PENGUJIAN UNTUK BAHAN UJI KACA ( DESIGN OF BENDING HYDRAULIC SYSTEM TEST EQUIPMENT AND MATERIALS TESTING RESULTS FOR GLASS TEST )

Uji lengkung (bending test) merupakan salah satu jenis pengujian bahan yang dilakukan untuk mengetahui sifat mekanik suatu bahan teknik. Dalam prakteknya masih sedikit para praktisi pengujian bahan yang memperhatikan aspek dan pengaruh variasi dimensi benda uji terhadap data hasil uji lengkung. Untuk itu alat uji bending ini dibuat untuk mempelajari pengaruh variasi dimensi benda uji pada pengujian lengkung. Pengujian dilakukan dengan menggunakan alat uji bending sistem hidrolik dengan dimensi alat 600x75x750 mm. Dan pengujian terhadap bahan uji kaca dengan tiga variasi dimensi yaitu 50x40x12 mm, 50x40x8mm dan 50x40x6 mm, dan metode yang digunakan dalam pengujian ini adalah three point bending dan four point bending. Data tekanan dongkrak, simpangan dan waktu diambil hingga spesimen/benda uji mendapatkan tekanan maksimal dari gaya tekan hidrolik. Hasil pengujian menunjukkan bahwa dimensi benda uji mempengaruhi gaya tekan yang terjadi pada saat pengujian. Semakin kecil dimensi yang di uji maka semakin kecil pula gaya tekan yang di timbulkan. Pada saat melakukan bending test, nilai rata-rata flexural strength yang didapatkan dengan menggunakan metode three point bending untuk kaca Mulia dengan ketebalan 12 mm sebesar 7,514 kg/mm2 dan pada saat melakukan pengujian dengan four point bending belum berhasil dikarenakan manometer yang digunakan tidak mencukupi kapasitasnya, untuk kaca Mulia dengan ketebalan 8 mm nilai rata- rata Flexural Strength dengan menggunakan metode three point bending sebesar 7,386 kg/mm2 dan untuk pengujian four point bending nilai rata-rata flexural strength sebesar 8,962 kg/mm2.Sedangkan untuk kaca Mulia dengan ketebalan 6 mm nilai rata- rata Flexural Strength dengan menggunakan metode three point bending sebesar 8,256 kg/mm2 dan untuk pengujian four point bending nilai rata-rata flexural strength sebesar 9,944 kg/mm2 Kata Kunci: Bending test, three point bending, four point bending, flexural strength, dimensi Bend test (bending test) is one type of material testing conducted to determine the mechanical properties of a material engineering. In practice there are still few practitioners who pay attention to aspects of materials testing and the influence of variations in the dimensions of the specimen to bend test result data. For the bending test equipment is designed to study the effect of variations in the dimensions of the specimen on the test arch. Tests carried out using test equipment with a hydraulic system bending tool dimensions 600x75x750 mm. And testing of test materials with three-dimensional variations of glass that is 50x40x12 mm, 50x40x8mm and 50x40x6 mm, and the methods used in this test is the three-point bending and four point bending. Jack pressure data, the deviation and the time taken until the specimen / test object to get the maximum pressure of the hydraulic press style. Test results show that the dimensions of the specimen affects the compressive force that occurs during testing. The smaller dimensions in the smaller trials also compressive force that caused. At the time of bending test, the average value of flexural strength obtained by using three-point bending to the glass with a thickness of 12 mm Honor of 7.514 kg/mm2 and during the four-point bending test has not been successful due to the manometer used is not sufficient capacity , for glass thickness 8 mm Majesty with the average value of Flexural Strength by using three-point bending method of 7.386 kg/mm2 and a four-point bending test for the average value of 8.962 kg/mm2. flexural strength for glass with thickness 6 Noble mm average value Flexural Strength by using three-point bending method of 8.256 kg/mm2 and a four-point bending test for the average value of flexural strength of 9.944 kg/mm2 Keywords: Bending test, three-point bending, four point bending, flexural strength, dimensiona

Design of a four-point bend test for ultra-low cycle fatigue of pipelines under inelastic bending

This master thesis is situated in the research domain dealing with the ductile failure of pipelines under extreme loading conditions. It is part of an umbrella research aiming to develop innovative experimental and computational methodologies to simulate fracture of steel structural elements under ultralow cycle fatigue. The focus of this study is on steel pipeline applications. The objective of this thesis is to design a large-scale four-point bend test setup to cyclically bend pipes. The feasibility of instrumentation will be evaluated using small scale test specimens. In this paper some ideas, constraints and opportunities for the design are considered, based on a literature review of several test setups for other applications. The design parameters have been calculated to compose the design windows and an initial overview of the possible instrumentation is given

Behaviour of Composite I-Beams Under Crushing and Bending Modes

Experimental and finite-element analyses for glass/epoxy composite I-beams were carried out to determine the effect of number of layers on load-carrying capacity and specific energy absorption. The loading modes used throughout this investigation were the axial compression,three and four point bending. The beams were fabricated from woven roving glass fibre and epoxy. The composite I-beams fabricated for axial compression tests were of 250 mm gauge length, 76 mm flange width and 125 mm web height,while the composite I-beams fabricated for three and four point bending tests were of 500 mm gauge length, 76 mm flange width and 125 mm web height.The matrix used was made of an epoxy resin (LECO 811-563-103) and a hardener (LECO 811-563-104) which were mixed at 8:1 ratio.Loading arrangements were also built to facilitate the experimental tests needed.The composite I-beams fabricated and tested were of 4, 6, 8 and 10 layers. Three samples were tested for each type and each load case. In addition,tensile samples were prepared and tested for the composite material used to evaluate the mechanical properties needed in the theoretical analysis stage of this project.Loaddisplacement results were first obtained directly for each type of samples and for each loading mode. An average, for each three similar tests,were then tabulated for the next phase of results and calculations. Experimental results obtained from this study included the first crushing load, the energy absorption and the failure modes.The first crushing load values of composite I-beams with four, six, eight and ten layers under axial compression, three and four point bending are (41.67, 69.46, 133.1 and 222.89 kN),(5.94, 11.24, 16.57 and 23.86 kN) and (8.00, 16.39, 25.08 and 35.01 kN) respectively.The specific energy absorption values of composite I-beams with four, six, eight and ten layers under axial compression are 9.79, 14.70, 33.18 and 35.88 (kJ/kg), respectively.Whereas, the energy absorption capability values of composite I-beams with four, six, eight and ten layers under three and four point bending are (235.785, 485.791, 829.500 and 1163.771 (J)) and (201.425, 422.107, 803.622 and 1006.986 (J)), respectively.Moreover, the initial crushing bending moment values of composite I-beams with four,six, eight and ten layers under three and four point bending are (0.66, 1.26, 1.86 and 2.68 (kN.m)) and (0.6, 1.23, 1.88 and 2.62 (kN.m)) respectively. On the other hand, all composite I-beams tested under axial compression fail by local buckling followed progressive crushing failure modes.Whereas, those tested under three and four point bending fail by matrix cracking followed local buckling under the loading point

RANCANG BANGUN ALAT UJI BENDING SISTEM HIDROLIK DAN HASIL PENGUJIAN UNTUK BAHAN KUNINGAN ( BENDING DESIGN OF HYDRAULIC SYSTEM TEST EQUIPMENT AND MATERIALS TESTING RESULTS FOR BRASS )

Uji lengkung (bending test) merupakan salah satu jenis pengujian bahan yang dilakukan untuk mengetahui sifat mekanik suatu bahan teknik. Dalam prakteknya masih sedikit para praktisi pengujian bahan yang memperhatikan aspek dan pengaruh variasi dimensi benda uji terhadap data hasil uji lengkung. Untuk itu alat uji bending ini dibuat untuk mempelajari pengaruh variasi dimensi benda uji pada pengujian lengkung. Pengujian dilakukan dengan menggunakan alat uji bending sistem hidrolik dengan dimensi alat 600x75x750 mm. Dan pengujian terhadap bahan uji kuningan dengan tiga variasi dimensi yaitu 50x5x6 mm, 50x4x6 mm dan 40x3x6 mm, dan metode yang digunakan dalam pengujian ini adalah three point bending dan four point bending. Data tekanan dongkrak, simpangan dan waktu diambil hingga spesimen/benda uji mendapatkan tekanan maksimal dari gaya tekan hidrolik. Hasil pengujian menunjukkan bahwa dimensi benda uji mempengaruhi gaya tekan yang terjadi pada saat pengujian. Semakin kecil dimensi yang di uji maka semakin kecil pula gaya tekan yang di timbulkan. Pada saat melakukan bending test, nilai rata-rata flexural strength yang didapatkan dengan menggunakan metode trhee point bending sebesar 95.584 kg/mm2 dan pada saat melakukan pengujian dengan four point bending belum berhasil dikarenakan manometer yang digunakan tidak mencukupi kapasitasnya. Kata Kunci: Bending test, three point bending, four point bending, flexural strength, dimensi Bending test is one type of material testing conducted to determine the mechanical properties of a material engineering. In practice there are still few practitioners who pay attention to aspects of materials testing and the influence of variations in the dimensions of the specimen to bend test result data. For the bending test equipment is designed to study the effect of variations in the dimensions of the specimen on the test arch. Tests carried out using test equipment with a hydraulic system bending tool dimensions 600x75x750 mm. And testing of test material brass with three variations of dimensions 50x5x6 mm, mm 50x4x6 and 40x3x6 mm, and the methods used in this test is the three-point bending and four point bending. Jack pressure data, the deviation and the time taken until the specimen / test object to get the maximum pressure of the hydraulic pressstyle. Test results show that the dimensions of the specimen affects the compressive force that occurs during testing. The smaller dimensions in the smaller trials also compressive force that caused. At the time of bending test, the average value of flexural strength are obtained using methods trhee point bending at 95,584 kg/mm2 and during the four-point bending test has not been successful due to the manometer used is not sufficient capacity. Keywords: Bending test, three-point bending, four point bending, flexural strength, dimensiona

Surface Conductivity of Si(100) and Ge(100) Surfaces Determined from Four-Point Transport Measurements Using an Analytical N-Layer Conductance Model

An analytical N-layer model for charge transport close to a surface is derived from the solution of Poisson's equation and used to describe distance-dependent electrical four-point measurements on the microscale. As the N-layer model comprises a surface channel, multiple intermediate layers and a semi-infinite bulk, it can be applied to semiconductors in combination with a calculation of the near-surface band-bending to model very precisely the measured four-point resistance on the surface of a specific sample and to extract a value for the surface conductivity. For describing four-point measurements on sample geometries with mixed 2D-3D conduction channels often a very simple parallel-circuit model has so far been used in the literature, but the application of this model is limited, as there are already significant deviations, when it is compared to the lowest possible case of the N-layer model, i.e. the 3-layer model. Furthermore, the N-layer model is applied to published distance-dependent four-point resistance measurements obtained with a multi-tip scanning tunneling microscope (STM) on Germanium(100) and Silicon(100) with different bulk doping concentrations resulting in the determination of values for the surface conductivities of these materials.Comment: 11 pages, 6 color figure

Four-point bending evaluation of dentin-composite interfaces with various stresses

Fracture properties of composite-dentin beams bonded with a self?etching adhesive were tested following short term pretreatments to simulate potential degradation mechanisms (thermal cycling, immersion in 5% NaOCl, or fatigue cycling). Beams of rectangular cross-section were shaped to a size of ~0.87 x 0.87 x 10 mm and placed in a four-point bending apparatus, with the loading points 1.8 and 7.2 mm apart, with the interface centered between the inner rollers. Testing was performed in Hanks? Balanced Salt Solution at 25 ?C . Solid dentin and solid composite beams [n = 6] had bending strengths of 164.4 and 164.6 MPa, respectively, under monotonically increasing loads. Bonded beams [n = 6] had strengths of 56.3 MPa. Thermo-cycling (5? to 55?C), NaOCl solution immersion, or 105 of pre-fatigue cycles did not decrease the strength. Conclusion: Thermal stress, exposure to NaOCL, or 105 cycles of mechanical stress does not decrease bond strength of composite bonded to dentin as tested in four-point bending