Effect of Pad Material, Copper Vs. Steel, On the Performance of a Tilting Pad Journal Bearing: Measurements and Predictions

The paper presents measurements of performance conducted on a copper pads bearing (C-PB) and a steel-pads bearing (S-PB). Both bearings have the same geometry and differ on the pads' backing material, copper vs. steel. The journal diameter D=102 mm, and a bearing has five pads with length L=0.4D, nominal radial clearance 0.064 mm. The bearings operate at four shaft speeds ranging from 6 krpm to 14 krpm and under multiple specific loads ranging from 0.17 MPa to 2.1 MPa. At the highest load (on pad) and low speed, the S-PB static eccentricity is up to 37% higher than that for the C-PB. The oil exit temperature rise is similar for both bearings, the maximum difference reaches 6 °C. For all operating conditions, the pads' peak temperature rise, having a maximum difference of 5 °C to 16 °C, is larger for the S-PB. The S-PB produces a ~ 5% lower drag power loss than that in the C-PB. From dynamic load test results, the C-PB direct stiffness KYY (along the load direction) is up to 30% higher than the S-PB stiffness, while the difference in KXX between the C-PB and the S-PB ranges from 60% to 90%. Similar to the stiffness results, the C-PB produces larger direct damping coefficients; CYY and CXX are up to 25% and 40% larger than those for the S-PB.

Design and Analysis of a Dynamic Loading System for a Morphing Winglet

The following thesis paper investigates the possible methods to perform a dynamic load test on a morphing winglet. A morphing winglet design capable of deflecting in the cant direction was developed by a joint partnership between Ryerson University and Bombardier Aerospace. In order to validate the model and complete a proof of concept, a loading fixture was required to test the structural integrity of the winglet under a defined load. Upon completion of an enumeration study of planar four-bar linkages, a passive R-P-R-P mechanism was designed to apply a constant perpendicular load throughout the cant motion. A design of the half size loading fixture was developed, optimized and manufactured to integrate with an existing cant module. The dynamic loading model was validated by producing a positive correlation between the theoretical analysis and the experimental results, leading to a successful proof of concept for a full scale test.

Design and Analysis of a Dynamic Loading System for a Morphing Winglet

The following thesis paper investigates the possible methods to perform a dynamic load test on a morphing winglet. A morphing winglet design capable of deflecting in the cant direction was developed by a joint partnership between Ryerson University and Bombardier Aerospace. In order to validate the model and complete a proof of concept, a loading fixture was required to test the structural integrity of the winglet under a defined load. Upon completion of an enumeration study of planar four-bar linkages, a passive R-P-R-P mechanism was designed to apply a constant perpendicular load throughout the cant motion. A design of the half size loading fixture was developed, optimized and manufactured to integrate with an existing cant module. The dynamic loading model was validated by producing a positive correlation between the theoretical analysis and the experimental results, leading to a successful proof of concept for a full scale test.

Use of the dynamic load test to obtain the pile capacity – the Brazilian experience

The dynamic load test is currently an important and usual tool for design, control, and quality assurance of deep foundations. The objective of this paper is to compare the expected geotechnical load capacity through empirical and semi-empirical Brazilian methods with the ultimate pile load obtained from the interpretation of Dynamic Load Tests (DLT; PDA). The stress-settlement curve was constructed from CAPWAP analysis with blows of different drop heights of increasing energy – test procedure proposed by Aoki (1989). Continuous flight augering (CFA) Franki and Root piles were evaluated in this study. These piles were tested in different cities in Brazil. Additionally, DLT results were compared with static load tests, and a good correlation was found with these field tests. The article aims to provide comparative background to guide foundation designers, as well as those who routinely develop these projects in Brazil.

ALTERNATIF UJI BEBAN PADA STRUKTUR (STUDI KASUS : JEMBATAN BAJA)

The most common structural load test that has been widely used is the static load test. An alternative to the structural load test is dynamic load test. Dynamic testing is a test carried out to determine level of structural stiffness or structural elements stiffness in the form of natural frequencies, while the static load test is intended to obtain responses of static loading from the structure in the form of deflection. The discussion will emphasize the correlation between static load test and dynamic load test. To correlate the static load test with the vibration test, a reference or value that comes from modeling or theoretical analysis is needed. Structural modeling is carried out to obtain the theoretical natural frequency and the theoretical deflection which will then be compared with the natural frequency of the vibration test (dynamic). If the frequency of the test results and the theoretical frequency are compared to the theoretical deflection, the prediction of the test deflection will be obtained. The correlation between the predicted deflection of the test and deflection of the static load test is quite close with a difference of less than 12%. Judging from the above correlation, periodic inspections of the tested structures can be considered for vibration testing only. The types of structures reviewed are simple span steel bridge structure, simple span + link slab steel bridge structure and continuous span steel bridge structure. Keywords: modeling; natural frequencies; vibration testing; static load test AbstrakUji beban struktur yang umum dan sudah banyak dilakukan adalah uji beban statik. Alternatif lain dari uji beban adalah dengan melakukan pengujian vibrasi (dinamik) pada struktur. Pengujian vibrasi (dinamik) dilakukan untuk mengetahui tingkat kekakuan struktur atau elemen struktur berupa frekuensi alami, sedangkan uji beban statik dimaksudkan untuk mendapatkan respons hasil pembebanan statik dari struktur berupa lendutan. Pembahasan akan menekankan kepada korelasi antara uji beban statik dan uji beban vibrasi (dinamik). Untuk mengkorelasikan pengujian beban statik terhadap pengujian vibrasi (dinamik) diperlukan suatu acuan atau nilai yang berasal dari analisa pemodelan atau teoritis. Pemodelan struktur dilakukan untuk mendapatkan frekuensi alami secara teoritis dan lendutan teoritis yang kemudian akan dibandingkan dengan frekuensi alami hasil uji vibrasi (dinamik). Jika frekuensi hasil uji dan frekuensi teoritis dibandingkan terhadap lendutan teoritis maka akan didapatkan prediksi lendutan uji. Hasil korelasi antara prediksi lendutan uji terhadap lendutan uji beban statik cukup mendekati dengan perbedaan kurang dari 12%. Dilihat dari korelasi diatas, maka untuk pemeriksaan berkala pada struktur yang telah diuji dapat dipertimbangkan untuk dilakukan pengujian vibrasi saja. Jenis struktur yang ditinjau adalah struktur jembatan baja simple span, simple span + link slab dan continuous span.

Evaluation of bearing capacity of reinforced concrete box ribbed arch bridge based on dynamic load test

Dynamic load test is to measure the natural vibration characteristics of the bridge structure or the forced vibration characteristics under dynamic load, and to evaluate the driving performance, driving safety and comfort of the bridge through dynamic load test. In order to evaluate the stress state and working performance of a reinforced concrete box-ribbed arch bridge, the load test of the bridge is carried out. Dynamic load test is used to test the inherent fundamental frequency, damping ratio and impact coefficient of the bridge through pulsation test and sports car test. Through the experiment with the key parts of the stress (strain) and displacement load and other important data, through analysis and study, the comprehensive analysis of the phenomenon of calculation and test, a comprehensive performance evaluation structure and function whether meet the design requirements, to provide technical basis for the safety of the bridge operation, and provide the original material for the bridge maintenance and management in the future.

Dynamic load test and lateral load distribution of a modified rigid frame bridge

In order to evaluate the stress state and working performance of a rigid frame bridge after reconstruction and extension, load test and transverse load distribution were carried out. Static load test is the test of stress at each section of main beam under the action of partial load and medium load. Dynamic load test is used to test the inherent fundamental frequency, damping ratio and impact coefficient of the bridge through pulsation test and sports car test. The results show that the first order vibration of the bridge is mainly transverse vibration from the measured modal parameters, which is consistent with the characteristics of higher pier and greater flexibility. The vibration characteristics of the bridge structure are low frequency and small damping vibration, the value of which belongs to the normal range among similar bridge structures, the overall stiffness of the bridge structure is normal, and the measured impact coefficient during the test of sports car is less than the design impact coefficient, indicating that the dynamic stiffness of the bridge meets the design and specification requirements.