Ultrasonic Inspection for Welds with Irregular Curvature Geometry Using Flexible Phased Array Probes and Semi-Auto Scanners: A Feasibility Study

Pipes of various shapes constitute pipelines utilized in industrial sites. These pipes are coupled through welding, wherein complex curvatures such as a flange, an elbow, a reducer, and a branch pipe are often found. Using phased array ultrasonic testing (PAUT) to inspect weld zones with complex curvatures is faced with different challenges due to parts that are difficult to contact with probes, small-diameter pipes, spatial limitations due to adjacent pipes, nozzles, and sloped shapes. In this study, we developed a flexible PAUT probe (FPAPr) and a semi-automatic scanner that was improved to enable stable FPAPr scanning for securing its inspection data consistency and reproducibility. A mock-up test specimen was created for a flange, an elbow, a reducer, and a branch pipe. Artificial flaws were inserted into the specimen through notch and hole processing, and simulations and verification experiments were performed to verify the performance and field applicability of the FPAPr and semi-automatic scanner.

G-Force Test Stand for the Evaluation of Weapon Component Strength

This paper discusses the design of a G-force test stand intended to examine of the effects of mechanical loads present during firing of a weapon and applied to the electronic components contained in the 155 mm calibre guided projectile. The G-force test stand is used to develop and test the effects of using high mechanical loads by decelerating a test specimen through the use of a purpose-designed fender assembly. For the purpose of testing, it is irrelevant whether a load is developed by acceleration or deceleration of the test specimen, as a test result obtained by the deceleration of a test specimen is equivalent to a test result obtained by the acceleration of a test specimen, as used in a 155 mm calibre artillery guided projectile. The G-force test stand was used to test and determine the velocities developed by the test specimens and the G-forces applied to them. The maximum velocity to which a test specimen was accelerated was approx. 72 m/s. The test stand was able to propel the test specimens to velocities an order of magnitude higher than the velocities obtained with a Kast and Masset ram. The tests were performed with rubber and copper fender assemblies. The effect of the specific fender used was demonstrated on the trend of the generated G-force. The test stand could develop G-forces in excess of 10,000 with a duration of more than 500 µs.

Release of Bisphenol A from Pit and Fissure Sealants According to Different pH Conditions

Changes in intraoral pH can cause changes in the chemical decomposition and surface properties of treated resin-based pits and fissure sealants (sealant). The purpose of this study is to evaluate the release of bisphenol A (BPA) from sealants under three different pH conditions over time. The test specimen was applied with 6 sealants 5 mg each on a glass plate (10 × 10 mm) and photopolymerized. The samples were immersed for 10 min, 1 h, and 24 h in solutions of pH 3.0, 6.5, and 10.0 at 37 °C. BPA release was measured using a gas chromatography-mass spectrometer. A statistical analysis was performed by two-way ANOVA and one-way ANOVA to verify the effect of pH conditions and time on BPA release. The BPA concentration in the pH 3.0 group was higher at all points than with pH 6.5 and pH 10.0 (p < 0.05), and gradually increased over time (p < 0.05). As a result, it was confirmed that low pH negatively influences BPA release. Therefore, frequent exposure to low pH due to the consumption of various beverages after sealant treatment can negatively affect the sealant’s chemical stability in the oral cavity.

The Analysis of Beam-Column Joint Reinforced with Cross Bars according to SK SNI T-15-1991-03 on Cyclic Loads

The primary structural component supporting the other structural loads in a building is the beam-column joint. It is considered a critical area of a building which needs to be accurately designed to ensure energy is dissipated properly during the occurrence of an earthquake. Beam-column joint has the ability to offer a proper structure required to transform cyclic loads in the inelastic region but also has a direct impact on the components connected to it during the occurrence of any failure. This is one of the reasons the beam-column connection needs to be designed carefully. Therefore, this study focused on designing a beam-column joint with reinforcement according to SK SNI T-15-1991 in order to withstand cyclic loads. The test specimen used was observed to have a concrete compressive strength of 19.17 MPa while the dimension of the beam was 120 x 30 x 40 cm and the column was 30 x 30 x 200 cm, having 8Ø13.4 mm bars with 310.03 MPa yield strength (fy) as well as Ø9.8-100 mm stirrup reinforcement with (fy) 374.59 MPa. The test was initiated through the provision of 0.75 mm, 1.5 mm, 3 mm, 6 mm, 12 mm, 24 mm monotonic cyclic loads at the end of the beam up to the moment the specimen cracked. A maximum load of 68.35 kN for the compression and 49.92 kN for the tension was required to attain the cyclic load capacity. The maximum load was attained at 50.98 mm displacement. Furthermore, beam-column with 23.93 mm displacement caused a reduction in capacity. Meanwhile, the load at 24 mm produced the cycle's highest dissipation energy of 13.25 but this can be increased through the addition of stirrups to provide stiffness in the joint. The stiffness value was also observed to have increased after the structural repairs.

Resistance of PLA Material Prepared By Additive Technology

The article studies the surface properties of PLA material prepared by additive technology, i.e. 3D printing. Samples with a square test area were printed by FFF technology. After 3D printing, the surface texture of the samples was evaluated in terms of microgeometry.Tribological tests were performed on the samples. The surface of the samples was cyclically stressed with the same load, always on the same path. Cyclic loading of the surface was performed on a UMT Bruker tribometer. The tribological properties between the sample surface and the test specimen in the shape of a ball were studied during the reciprocating motion. In particular, the coefficient of friction was measured and evaluated. The ball material was PTFE and Polypropylene.The wear parameters of samples and balls were documented and evaluated. The results of the tests are the load dependencies on the wear of the PLA material and the test specimens.

PERANCANGAN ALAT UJI DEFLEKSI BATANG KANTILEVER FLEKSIBEL

Deflection is the change in shape experienced by the beam in the y direction due to the vertical loading applied to the beam or bar. Cantilever rods are if one end of the beam/rod is clamped and the other end is free. In this study, a flexible cantilever rod deflection test device was designed. This tool is used to determine the deflection/deflection that occurs in the beam/strip plate after being given a load. The method used is library research, a data collection method that is carried out by reading, studying, and researching the relevant literature with the title of this thesis which aims to collect data and analyze a theoretical understanding. This research will focus on designing and testing flexible cantilever rod deflection test equipment and utilizing beam/ strip plate as a test specimen for flexible cantilever rods. This tool has a height of 100 cm and a width of 90 cm and this tool is equipped with an HC-SR04 sensor which is directly connected to a digital number. The results of testing the strip plate with a load of 1 kg and 1.5 kg using the HC-SR04 sensor showed that the deflection at the smallest end was 20 mm, and the largest value was 30 mm. the theoretical calculation with equation (2-9) obtained the smallest result of 1.06 mm and the largest value of 3.5 mm.Defleksi adalah perubahan bentuk yang dialami balok pada arah y akibat adanya pembebanan vertikal yang diberikan terhadap balok atau batang. Batang kantilever yaitu jika salah satu ujung balok/batang dijepit dan yang ujung lain bebas. Pada penelitian ini dirancang sebuah alat uji defleksi batang kantilever fleksibel alat ini difungsikan untuk menentukan lendutan/defleksi yang terjadi pada beam/plat strip setelah diberi beban. Metode yang digunakan yaitu dengan penelitian kepustakaan suatu metode pengumpulan data yang dilakukan secara membaca, mempelajari, dan meneliti literature-literature yang relevan dengan judul skripsi ini yang bertujuan untuk mengumpulkan data dan menganalisa suatu pengertian yang bersifat teoritis. Pada penelitian ini akan berfokus pada perancangan dan uji coba alat uji defleksi batang kantilever fleksibel dan memanfaatkan beam/plat strip sebagai bahan spesimen uji batang kantilever fleksibel. Alat ini mempunyai tinggi 100 cm dan lebar 90 cm dan alat ini dilengkapi dengan sensor HC-SR04 yang langsung terhubung dengan digital number. Hasil pengujian plat strip beban 1 kg, dan 1.5 kg menggunakan sensor HC-SR04 didapatkan hasil defleksi pada ujung yang terkecil yaitu 20 mm, dan pada nilai yang terbesar 30 mm. pada perhitungan secara teoritis dengan persamaan (2-9) didapatkan hasil terkecil 1.06 mm dan nilai yang terbesar 3.5 mm.

Analytical study on the effect of extreme seismic strains on the transverse buckling of ultra-reinforced seismic walls and their environmental design

In the context of the present work, the influence of the degree of tension on the phenomenon of transverse instability of reinforced concrete seismic walls is examined. Useful conclusions are drawn regarding the influence of the degree of elongation on the phenomenon of transverse buckling. These conclusions are substantiated both experimentally and analytically, as the results of the experiments are compared with the corresponding results of the analytical investigation. Moreover, some thoughts on a more environmental design of R/C seismic walls are stated. The present investigation is both experimental and analytical and consists of 4 test specimens. These specimens simulate the extreme boundary edges of structural walls. All columns simulate only the extreme reinforced areas of the walls, in order to study the basic mechanism of the phenomenon. The detailing of the specimens consists of 6 rebars with a diameter of 12 mm for each bar. The geometric dimensions are the same for all specimens. What differentiates the specimens from each other is the degree of tension they have sustained. More specifically, the tensile degrees used are 10‰, 20‰, 30‰ and 50‰. The loading stages of each specimen for all specimens are as follows: (a) Uniaxial central tensile loading on each test specimen apart from the specimen sustained 0‰ degree of tension; (b) Uniaxial central compression loading on each specimen till its failure due to buckling or due to an excess of its cross-section compressive strength. The present study focuses on the tensile loading stage only. Extreme tensile strengths are also used, e.g., 30‰ and 50‰, in order to take into account, the cases of extreme seismic excitations. The experimental study is followed by the numerical investigation of these 4 specimens using appropriate statistical software and finite elements.