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Fundamentals of Machine Component Design
... One of the most important equations governing the pressure in the lubricant film is Reynolds Equation, which represents the simplification of the Reynolds's paper in 1886 [2]. To apply this equation to the lubricant film, many assumptions should be considered [3]- [5]: ...
... Thickness [3], [4], [6] Relationship between Sommerfeld No. and the coefficient of friction [3], [4], [6] Relationship between Sommerfeld No. and the minimum film pressure ratio [3], [4], [6] ISSN: 2348 -8360 www.internationaljournalssrg.org Page 3 ...
... Thickness [3], [4], [6] Relationship between Sommerfeld No. and the coefficient of friction [3], [4], [6] Relationship between Sommerfeld No. and the minimum film pressure ratio [3], [4], [6] ISSN: 2348 -8360 www.internationaljournalssrg.org Page 3 ...
This paper illustrates evaluating performance parameters for the journal bearing design by using three different methods. In the first approach, Raimondi and Boyd Charts (Graphical) method will be used. The second approach represents the first analytical method called Reynold equations tables, which can be used by utilizing familiar equations connected by other values. The second analytical method by Reason and Narang (Combined Solution Method) requires using the empirical equation and tables. Finally, the error percentage for all performance parameters for the analytical methods will be compared with the graphical to show which method is more precise. The main goal of obtaining the precise procedure for the journal bearing performance parameters evaluation is to determine the exact temperature rise in journal bearing and the average temperature of the oil film inside the journal bearing. By knowing these temperatures, the designers can select the best type of lubricant oil and bearing material to avoid bearing failure
... In this case, all the variables used in the previous approach are no longer taken as deterministic variables and are taken as random variables. In addition, each variable is considered to have a normal distribution and its coefficient of variation is 10% [16]. To carry out this methodology, two variables are taken and combined using their means and standard deviations to obtain a new function with a normal distribution with its respective mean and standard deviation. ...
... However, since the dimensions of the geometry and the diameter of the shaft are not yet known, then according to [16] the initial values of KFF = 2 and KFT = 1.6 are used. Finally, before presenting the design of axis 2 through the three approaches, static, dynamic and binary synthesis, it is necessary to determine 1) the torque; ...
This article compares the traditional static and dynamic (fatigue) methodologies for the mechanical design of a shaft used in the speed reducer of an industrial fan against the probabilistic design methodology based on the binary synthesis method. To make the comparison, the case of the design of the diameter of the intermediate shaft of a speed reducer used between a motor and a fan used to dry grains is analyzed. The main objective is to show the advantage that the probabilistic approach offers over traditional axis design approaches. The effectiveness of the results of the methodologies is validated with the torsional rigidity allowed for the design of shafts. The diameter obtained by the static methodology and the one obtained by the fatigue methodology is smaller than the diameter obtained by the torsional stiffness, on the contrary, the diameter obtained by the binary synthesis probabilistic methodology is greater than the diameter of the torsional stiffness.
... Sci. 2020, 10, x FOR PEER REVIEW 3 of 16 external tightening and loosening torques and can be expressed in terms of the following twisting moment equilibrium equations: Based on the Motosh methodology and including the 3D effect of both the helix and thread profile angles the approximate torque tension relationship is to give [34,35]: ...
... where and are the maximum and minimum radius of the screw head contact surface, and and are the maximum and minimum radius of the screw thread contact surface (see Figure 2). Finally, the parameter is: Based on the Motosh methodology and including the 3D effect of both the helix and thread profile angles the approximate torque tension relationship is to give [34,35]: ...
Featured Application: A methodology to study screw self-loosening phenomenon in preliminary design stages of dental implants is presented. Abstract: Self-loosening of the prosthetic screws is a major mechanical problem affecting roughly 10% of dental implants, according to the literature. This phenomenon may lead to micro-movements that produce crestal bone loss, peri-implantitis, or structural failure of the implant assembly. In this paper, a simple and effective tool to predict self-loosening under masticatory loads is presented. The loads acting on the screw are obtained from a simple finite element (FE) model, and introduced in a mathematical formula that calculates the torque needed to loosen the screw; self-loosening will occur when this torque becomes zero. In this sense, all the parameters involved in self-loosening phenomenon can be easily identified, and their effect quantified. For validating purposes, 90 experimental tests were performed in a direct stress test bench. As a result, a powerful tool with a maximum experimental error of 7.6% is presented, allowing dental implant manufacturers to predict eventual occurrence of self-loosening in their developed dental implant products and take corrective actions at preliminary design stage. Furthermore, the following clinical implications can be directly derived from the methodology: a higher screw preload, that is a higher tightening torque, improves self-loosening response of the dental implant and, similarly, for a given preload force, higher friction coefficient and screw metric, as well as lower pitch and thread angle values, are also found to be beneficial.
... Masalah teknologi pada produk bogie di tentukan dari hasil pengujian dimana pada beberapa titik atau lokasi terjadinya konsentrasi tegangan yang mendekati batas tegangan yang diijinkan. Dengan kata lain, walaupun desain yang telah di buat cukup aman untuk di gunakan secara operasional, namun angka faktor keamanannya perlu di tingkatkan untuk mamastikan kehandalan produk tersebut [4][5][6][7][8][9]. Penelitian yang bertujuan untuk meningkatkan faktor keamanan bukan saja menjamin keamanan transportasi namun juga dapat memenuhi tuntutan pasar global dan keselamatan penumpang yaitu dengan dihasilkannya produk bogie kereta api berdaya saing tinggi [3]. ...
... Pemodelan elemen hingga di lakukan dengan cara menentukan mendefinisikan sumbu pada desain bogie dan menentukan type elemen [3][4][5][6][7][8][9] Sistem sumbu yang di gunakan : X: Sebagai sumbu longitudinal Y: sebagai sumbu vertikal Z: sebagai sumbu lateral ...
Kegiatan penelitian ini bertujuan untuk meningkatkan faktor keamanan bogie las lokomotif yang telah ada. Sasaran kegiatan penelitian ini yaitu didapatkannya desain optimal dari bogie las tersebut dengan cara rekayasa geometri dan struktur sehingga didapatkan efek penguatan. Dari hasil pengujian struktur bogie las frame lokomotif DH, struktur bogie frame masih perlu dilakukan penguatan karena pada saat pengujian statis tegangan maksimum yang terjadi hampir mendekati tegangan luluh materialnya. Untuk itu perlu dilakukan redesain untuk bogie frame dengan rekayasa geometri dalam bentuk penguatan pada struktur framenya. Penambahan penguatan ini akan di simulasikan dengan menggunakan sofware finite elemen method (FEM). Tujuannya dilakukan analisa kekuatan struktur bogie las frame lokomotif DH adalah untuk memastikan disain bogie las frame baru memenuhi standar keamanan sebelum melalui proses pengujian, atau sering disebut sebagai tahap verifikasi disain yang selanjutnya disain bogie frame ini dijadikan sebagai salah satu alternatif disain.
... Basically, the alignment zone is the second part of the tightener; in this zone, the fastener and the joint mating surfaces are drawn into alignment to obtain a possible snug condition. The elastic clamping is the third zone, where the slope of the torque-angle curve is alternatively constant [11,12]. The last zone, which is the post-yield zone, begins with an inflection point at the end of the elastic range. ...
In most mechanical systems, screw threads serve three main basic purposes: (i) to transmit power, (ii) to provide a clamping force, and finally (iii) to restrict or control motion. This chapter demonstrates the effects of friction and behavior which can occur in a bolted fastening (screw thread) for advanced design purposes. To model this behavior, other control components are attached to the bolted screw. The bolt preload is applied with a predetermined torque. For this case the preload depends on the friction under the head and in the thread. The friction prevents the loosing of the bolted fastening. This effect is termed as self-locking effect. We designed an algorithm that reproduces an exemplary simulation scenario, which determines friction and its effect on thread angle based on the strength of the coefficient of friction at a specific tension or clamp load value using the system-of-system approach. The result shows specific behavior on both the motion in threads and drive screw with predetermined torque. The chapter is limited to creating a simple simulation environment to demonstrate the effects.
... The list of references at the end of the paper provides a limited tally of what is available in the fields of machine element design, optimization and reverse engineering. Standard textbooks (Edwardo and McKee 1991, Metwalli 1991, Mott 1992, Shigley 1986, Spotts 1985 include design procedures of different machine elements that include basic standard geometries and dimensions for gears. Other references (Dippery and Echempati 1998, Dooner and Seireg 1998, Dudley 1984, Heikkinen, Korpela and Leinonen 1997, Jog and Pande 1989, Maitra 1985, Metwalli and El Danaf 1996 are devoted to gear design and optimization. ...
... The list of references at the end of the paper provides a limited tally of what is available in the fields of machine element design, optimization and reverse engineering. Standard textbooks (Edwardo and McKee 1991, Metwalli 1991, Mott 1992, Shigley 1986, Spotts 1985 include design procedures of different machine elements that include basic standard geometries and dimensions for gears. Other references (Dippery and Echempati 1998, Dooner and Seireg 1998, Dudley 1984, Heikkinen, Korpela and Leinonen 1997, Jog and Pande 1989, Maitra 1985, Metwalli and El Danaf 1996 are devoted to gear design and optimization. ...
This paper presents a new procedure by which standard machine elements can be reverse engineered. Standard elements or components need not be scanned and identified as surface or solid model. The standard character is sufficient to be identified by few parameters. These parameters can be measured or deduced by calculations from certain geometric relations. The procedure presented herein is devoted to the reverse engineering of spur and helical gears. Other standard machine elements can be treated the same way. A computer aided reverse engineering (CARE) program is used to satisfy all geometric constraints, identify other dependent geometries and define production and inspection requirements. It allows the further check of the design appropriateness of material selection and loading conditions.
... area A merupakan lokasi pembebanan di mana nantinya keping roda kereta api akan melewati area A. Area B yang berupa lubang merupakan lokasi untuk penempatan strain gauge [7]. Area ini di tentukan oleh hasil simulasi tegangan menggunakan software finite elemen method (FEM) [6,[8][9][10][11]. Area C sebagai fix support untuk load cell dalam arah sumbu x,y,z. ...
Uji Berat pada kereta atau gerbong dilakukan dengan cara menghitung total berat Kereta dan menghitung distribusi berat pada masing-masing roda dengan cara menimbang beban yang diterima pada setiap roda. Tujuan dari penelitian ini adalah membuat konsep desain dan perhitungan kekuatan struktur alat uji berat kereta portabel yang dapat di gunakan untuk mengukur berat kereta di sepanjang jalan rel secara efisien dan akurat. Pengukuran berat kereta dilakukan untuk memastikan berat kereta terdistribusi secara merata pada tiap roda kereta dan memastikan agar muatan kereta tidak melebihi batas kemampuan kemampuan jalan rel. Faktor input dalam penelitian ini adalah load atau beban, ukuran meshing, jenis material dan model load cell dan dudukan load cell. Proses penelitian yang di lakukan berupa desain dan simulasi menggunakan finite elemen method terhadap load cell dan dudukan load cell. Faktor output dari penelitian ini adalah kekuatan struktur dari load cell dan kekuatan struktur dari dudukan load cell. Nilai tegangan ijin untuk baja ASTM A36 sebesar 160 MPa. Nilai tegangan ijin untuk baja SM 490 sebesar 230, dan nilai tegangan ijin untuk baja ASSAB 718 sebesar 574. Nilai tegangan maksimum material yang masih di bawah nilai tegangan ijinnya adalah material Assab 718. Sehingga material ini di pilih sebagai material load cell dan dudukan load cell.
... Juvinall and Marshek [18] provided an equation for estimating the effective area of the clamped member, which is given by . Pedersen and Pedersen [19], performed contact finite element analysis to evaluate the member stiffness bases on elastic energy in the structure. ...
... En la literatura Especializada la inmensa mayoría de los autores [15,71] abordan los problemas relativos a la elevación de la resistencia de las uniones soldadas mediante el mejoramiento y control de los parámetros tecnológicos, su ejecución o los materiales de soldadura sin enfrentar el cálculo de las tensiones que aparecen en estas. ...
Se desarrolla un procedimiento general y expresiones de cálculo para determinar el valor de las tensiones en algunas uniones soldadas a tope y de filete, con perfil asimétrico sometidas a flexión transversal.
... Above 200 Bhn (hardened) 4 and above 8.8 and above 3.0 3.8 Table A2. Fatigue stress concentration factors for steel-threaded members [6]. Figure A1. ...
... As usual, high stresses occur at the screw fi rst threads, zone A, and at the extremities of the implant–abutment contact, zone B, and of the abutment–abutment screw contact, zone C. To reduce the screw stresses, zone A, the screw geometry may be modifi ed by stress shielding the thread with a groove, as in Figure 13. In addition, a variable pitch thread may be adopted in order to evenly distribute the forces between male and female, thus lowering the stresses in the vicinity of the fi rst threads [30][31][32][33][34][35][36]. The pitch variation is of the order of some micrometres, which appreciably increases the implant cost. ...
This chapter deals with biomechanical aspects in dental replacements. The state of the art is critically reviewed taking into account the body of the literature results. The initial section is devoted to the mechanical properties of bone and to a description of the jaw geometry and of its loading and constraining. The following section presents a classifi cation of the various tooth replacement confi gurations and of the various materials adopted, where single and multiple replacements are considered. A specifi c section is devoted to the solid modelling of the jaw as input to numerical analyses, where the aid offered by reverse engineering and tomography is underlined. The fi nite element method as well as alternative numerical and experimental approaches are reviewed in a dedicated section. The stress analysis forecasts and measurements are biomechanically interpreted in the light of the current literature results. The chapter ends with a section devoted to biological aspects.
... The adhesive wear distribution is estimated by defining a wear factor as the product of the groove-seal relative velocity and the asperity contact pressure. The actual wear rate would be estimated by multiplying this wear factor by a wear coefficient and dividing by the hardness [26]. The cycle-averaged wear factor distribution show local wear at the four contact lines (Figure 12). ...
... where F static is equal to the reaction on the wheel promoted by the vehicle weight and F din is the impact load on the tire. An estimate of F din based in a simple one-degree of freedom analytic model (spring-mass) can be obtained through an energy conservation analysis [9]: ...
... В Україні вимоги до виготовлення МК кранів взагалі та КБ зокрема регламентуються галузевими стандартами, де представлено ряд конструктивних і технологічних ре комендацій та вказано, що зварювання МК виконується за технологічними документами, в яких повинні бути передбачені порядок накладання швів та режими зварю вання. Технологія і режими зварювання оказують значний вплив на міцність конструкції [2][3][4][5], при цьому науково обґрунтованих рекомендацій щодо режимів накладання поясних швів кранових КБ на цей час не існує. Цим обґрунтовується актуальність проведеного дослідження. ...
The residual stress-strain state of welded joints of cranes’ steel structures is understudied scientific and technical issue. Finite-element analysis of the post-weld residual stresses in longitudinal T-joints of overhead cranes’ box girders was applied to this study. Goldak’s moving heat source model based on double-ellipsoid heat flux distribution was used. Thermal and mechanical tasks were sequentially solved, wherein the phase transformation processes were taken into consideration. The effects of such factors as box girder geometry, welding speed, pre-heating technology on the residual stresses and phase distribution in longitudinal welds were further investigated.
The post-weld stress-strain state of the box girders’ T-joints was detailed. The recommendations to streamline the overhead cranes girders’ production technology intended to improve their quality and overall technological level were formulated. The necessity of taking into account the phase and structural transformations in the simulation is proved. The requirements for the finite-element modeling of longitudinal T-joints were established.
... where k θ represents the torsional stiffness of the substitute inter-segmental joints between the spine and the legs as shown in Fig. 1c. The expression of k θ for a cantilever beam is given by EI /L [28]. However, k θ was determined experimentally in this study, since the elasticity of the aluminum cold-formed beams was not precisely known. ...
Today’s robots are able to perform very limited locomotion tasks by consuming high energy although animals are able to carry out very complicated but stable locomotion tasks using less control inputs and energy. Therefore, it is important to understand the principles of animal locomotion in order to develop efficient legged robots. This paper presents a U-shape visco-elastic beam mechanism that is able to run like a bounding animal when it is actuated by a simple pendulum at the torsional resonance frequency of the elastic body. A simple physical model has been developed to investigate the dynamics of the mechanism and the natural body dynamics of quadrupeds. In the mechanism, a small rotating mass was attached to a DC motor which was mounted on the center of the spine. When this motor is actuated at around the torsional resonance frequency of the elastic body, the robot starts to move and it exhibits a self-organized locomotion behavior. The self-organized locomotion process of the robot does not require any central authority, sensory feedback or external element imposing a planned motion. Comparing the bounding locomotion of the beam mechanism with those of well-known quadrupeds such as a horse, greyhound and cheetah, it can be concluded that the pendulum-driven U-shaped visco-elastic beam displays kinematic behavior similar to a horse, in terms of both experimental and simulation results. Interestingly, this bounding locomotion occurs only if the shape ratio and the actuation frequencies of the beam are close to those of the fastest quadrupeds.
Basic Euclidean geometry works very well on paper and in the abstract, with its straight lines, assumed parallels, and perfect circles. A student can learn how two points form a line, and two lines form a triangle. All on paper, The third dimension necessitates some clumsy drawings and a leap of faith. If you look at a basic cube, a sphere, or a cylinder, students must understand that you've gone from squared to cubed. Students can now design objects in computer-aided drawing projects (CAD) and work with a developing line of hobbyist three-dimensional printers. This is a feasibility study to explore geometry, trigonometry, and calculus projects on low-cost 3D printers. The project will include several test lessons to test some or all of the studies with high school students.
The local strain method for estimating fatigue life employs the stresses and strains that occur at critical, high-strain regions, such as geometric notches, where fatigue cracks are likely to start. Materials properties are defined that give cyclic stress-strain curves and strain-life curves. These curves need modification for biaxial or triaxial stress, and strain-life curves can be adjusted to include surface finish and size effects. The effect of mean stress can be included in strain-life curves by the methods of Morrow, or Smith, Watson and Topper, or Walker. To make estimates of fatigue life for notched members, the local stresses and strains that occur at the notch during cyclic loading need to be calculated or estimated, with Neuber’s rule being a suitable estimation method. When used with the cyclic stress-strain curve, this rule may be applied to cyclic loading, and even to irregular variation of load with time. For irregular loading, the plasticity memory effect is employed to identify closed stress-strain hysteresis loops, which correspond to cycles counted by the rainflow method, enabling life estimates based on the Palmgren-Miner rule. Some additional considerations are discussed: mean stress relaxation, overload effects, sequence effects, fatigue limit effects, crack growth effects, and the use of a component-specific strain-life curve.
Shot-peening treatment was applied to a quenched and tempered DIN 34CrNiMo6 steel to improve its high-cycle R: -1 axial fatigue strength. Compared with the machined condition, the increase in the fatigue limit was 21.8%. S-N curves for shot-peened and the as machined condition were presented and compared with those obtained in previous research for rotating bending fatigue, including curves for mirror-polished specimens.
The applied shot-peening treatment in this work (Isp: 8A and 200% coverage) for quenched and tempered (Q+T) DIN 34CrNiMo6 steel introduced a compressive residual stress field and an increase in surface roughness, as well as minor variations in microstructure, hardness and the FWHM (full width of the diffraction peak at half maximum intensity) parameter.
The introduced compressive residual stress field tended to reduce when an external stress is applied. This was due to the onset of plastic strain. In this paper, two types of quasi-static tests were conducted by applying an axial stress with six different magnitudes and in the two directions (compressive or tensile). This was in order to assess their influence on the relaxation of surface residual stresses. Due to the introduced compressive residual stresses, if the applied stress was compressive, the onset of plastic deformations was achieved with a lower stress magnitude.
In addition, surface residual stress relaxation under cyclic applied stress was evaluated at four different stress magnitudes. Due to the cyclic-softening behaviour of this Q+T steel, its cyclic mechanical properties must be considered to assess the onset of plastic strains. With the experimental data, a logarithmic model to predict the evolution of surface residual stresses with the number of cycles for different applied stress magnitudes was presented.
Volume 2B covers the metallurgy, processing, fabrication, properties, and performance of aluminum alloys. The articles in the first section of the volume provide details on the selection of aluminum alloys to meet specific design and performance criteria. The next section presents in-depth datasheets for standard grades of wrought and cast aluminum alloys. The datasheets are designed for easy look up of details on alloy metallurgy, processing effects on properties, and fabrication characteristics. The volume appendices address aluminum alloy temper designations and definitions, aluminum filler metal selection, nominal compositions and composition limits for wrought and cast aluminum alloys, and typical room temperature physical properties of wrought aluminum alloys. For information on the print version of Volume 2B, ISBN 978-1-62708-208-2, follow this link.
The Mechanical Engineering essence is the understanding of all the available resources, their effective utilization, and making use of the law of nature to help, gain and benefit the entire humanity. Mechanical Engineering is the applied science using scientific knowledge and procedures as the means to accomplish a specific practical and useful results. It is related to the sense that involves a proper understanding of all the scientific principles and effectively applying them to attain the designated goal. The machine design in mechanical engineering is the most crucial section of engineering, and it deals with the design, conception, refinement, development of machines and component application together with the mechanical apparatus of every kind.
In the professional engineering, the main concern is to obtain the requisite solutions to all the practical problems in the machinery production. The solutions should reflect the knowledge, understanding and application of the underlying technology and science. However, normally the mere understanding is not sufficient. The related empirical knowledge together with engineering judgment become the most prerequisite. For instance, no scientist can entirely understand electricity. However, it does not prevent any electrical engineer from creating highly useful and functional electrical devices. Likewise, no scientist can fully understand metal fatigues and combustion procedures, yet, the mechanical engineers utilize the knowledge and insight available to generate highly useful and functional combustion engines. When more scientific solutions are accessible, engineers can devise better explanations and clarifications to practical problems. This study tries to analyze and evaluate the perception and usefulness of AM- additive manufacturing systems and technologies to understand machine elements, product design and its development.
Shafts of centrifugal pumps are both load bearing and power transmitting component which are usually composed of martensitic stainless steel. In this paper, an attempt is made to manifest how minute deviations from the standard dimensions of the keyway of a shaft leads to the occurrence of premature torsional fatigue along the keyway seat. Microstructural characterization via optical microscope, SEM and EDS further revealed faulty heat treatment of the material that resulted in inferior mechanical properties which assisted in the accelerated crack propagation and ultimate failure of the shaft within 2.5 years of service leading to a shutdown of blast furnace for approximately 10 hours. Comparative material analysis was carried out on samples of shaft from other pumps in service (which has not failed) to manifest that proper heat treatment of the shaft material can bring about desired mechanical properties of component and procrastinate the failure.
In this chapter, after a brief examination of the various types of wear that can be found in the gears, the abrasive wear generation mechanism and the related influences are described. The main classic wear theories are then recalled, together with the equations that, for each of them, express the correlations between the various quantities involved. Attention is then focused on the assessment of tooth wear linear progression and, in this regard, the various criteria for checking abrasive wear in the gears are described. Finally, additional considerations on the gear wear are made.
In this chapter, a general survey is first done on the surface durability (pitting) of spur and helical gears, also focusing attention on pitting damage and safety factor to be used in their design. The theoretical bases of surface durability are then discussed, with particular reference to the surface and subsurface stress states that occur in sliding and rolling contacts between the mating surfaces of the conjugate flanks of the teeth in relative motion. In this framework, same brief reminder on the elastohydrodynamic lubrication theory is provided, also describing the great influence it exerts on the aforementioned contacts as well as the EDH lubrication conditions necessary to reduce or avoid surface and subsurface fatigue damages in these types of gears. Finally, the procedure for calculating the surface durability of these same gears in accordance with the ISO standards is described, highlighting when deemed necessary as the relationships used by the same ISO are anchored to the theoretical base previously discussed.
In this chapter, the general concepts of ordinary gear trains are first described, particularly those concerning their efficiency and the obtainable transmission ratios. The same concepts are then extended to planetary gear trains and various methods of calculating the transmissions ratios achievable with these types of gear drives are defined. Some problems related to simple planetary gear trains are then examined, and the main characteristics of some of these gear drives are described and discussed. Particular planetary gear trains are then dealt with, such as those concerning summarizing and differential gear trains. The analysis is then extended to multi-stage planetary gear trains and parallel mixed power trains consisting of ordinary and planetary gear trains, and the calculation procedure is described of the braking torque to be applied to the members of the planetary gear train that are held at rest. Finally, the problem of the efficiency of a planetary gear train is addressed and discussed in its general terms, also with reference to those particular planetary gear trains used to realize large transmission ratios.
The capability to predict fatigue damage continues to be critical for determining the operational life and inspection intervals of connectors and components used in offshore applications. Subsea well intervention systems are subjected to wave induced cyclic bending moments and understanding the fatigue performance of equipment is essential for determining safe operating envelopes.
In this paper, a validated fatigue analysis methodology is presented for non-preloaded connectors that are used within subsea well intervention systems. The fatigue analysis methodology addresses limitations in current standards when calculating the fatigue capacities of non-preloaded connectors with different interacting component materials (i.e. low alloy steel and nickel based alloys). The methodology considers the effect on the fatigue life of both non-axisymmetric geometry/loading, FAT loading, as well as the interaction of different connector materials, capturing any potential change in hot spot locations.
Three different non-preloaded connections (i.e. consisting of threaded and load shoulder connectors) were analysed using 3-D finite element analysis models, where ΔM-N curves and the associated crack initiation locations were calculated for each connector. Full-scale resonance fatigue tests were successfully performed on the three different connector types, validating the ΔM-N curves calculated using the fatigue analysis methodology. Fatigue failure (i.e. through-wall crack) was achieved in all tests between 100,000 and 5,000,000 cycles matching the predicted crack initiation location from the analysis for each connection. The validated methodology provides accurate calculation of the fatigue life and correct identification of hot spot locations. Using the validated approach described in this paper within the design process can lead to significant improvements in future designs of connectors, enabling safer operational limits and extending the service life of subsea systems.
Preface
Failure analysis has gradually become the crucial method in investigating engineering com‐
ponents or machine failures. The costs of repair and operation breakdowns make an alarm‐
ing sign for designers, engineers and manufactures on whether or not to keep the existing
machines, worthwhile of repairing, or the machines or components need to be redesigned.
This book covers recent advancement methods used in analysing the root of engineering
failures and the proactive suggestion for future failure prevention. The techniques used, es‐
pecially non-destructive testing such X-ray, is well described. The failure analysis covers
materials for metal and composites for various applications in mechanical, civil and electri‐
cal applications. The modes of failures that are well explained include fracture, fatigue, cor‐
rosion and high-temperature failure mechanisms. The administrative part of failures is also
presented in the chapter of failure rate analysis.
The book will bring you on a tour on how to apply mechanical, electrical and civil engi‐
neering fundamental concepts and to understand the prediction of root cause of failures.
The topics explained comprehensively the reliable test that one should perform in order to
investigate the cause of machines, component or material failures at the macroscopic and
microscopic level.
I hope the material presented in this book, is not too theoretical and you find the case study,
the analysis will assist you in tackling your own failure investigation case.
Last but not least, I would like to thank all authors who made their contribution and sup‐
port for this book to be realised.
Prof. Dr. Aidy Ali
Department of Mechanical Engineering, Faculty of Engineering,
National Defence University of Malaysia (UPNM),
Kuala Lumpur, Malaysia
A critical aspect of standard test methods for fatigue characterization is that they do not provide any information on heat dissipation in the material and involve very expensive experimental campaigns in time and costs. In recent years, thermographic methods capable of reducing testing time have been developed, also providing more information on damage occurring in the material. A commonly used approach is based on the assessment of the temperature plateau during a stepwise loading procedure. At times, however, this approach can fail if temperature stabilization is not achieved. In this regard, in this paper, a new approach based on the assessment of 3 different thermal indexes was proposed to estimate the fatigue limit of 3 stainless steels: AISI 316, 17-4PH, and ASTMA890 grade 4a, respectively, exhibiting fully austenitic, fully martensitic, and duplex biphasic microstructure. The fatigue tests were carried out by using a stepwise loading procedure, under loading ratio of 0.5.
This paper presents a design method to optimize the material distribution of
zirconia/aluminum -functionally graded material with respect to some buckling and vibration
properties. The distribution of volume fractions of the FGM constituents is defined through the
beam or column length by a trigonometric law. The finite element method is used for the buckling
and vibration analysis, and a genetic algorithm is utilized for optimization of the chosen objective
function. The efficiency of the method is demonstrated by two design problems. In the first design
problem, FGM is used to maximize the buckling crical load to weight ratio. In the second design
problem, the kinetic energy of a vibrating FGM beam is minimized at a specific excitation
frequency. These design problems show that material tailoring of beam/column structures using
FGM can result in substantial improvements of their buckling and vibration characteristics.
The design and calculation of a spur gear transmission, one of the often-performed mechanical engineering tasks, requires a lot of long and complicated tedious computations. With today's modern technology that process that could be easily simplified by the use of the computer. However, the result for successful work of the computer programmer will be only as good as the accuracy of data of the input information as well as the procedure of calculation, provided by mechanical engineering science. In this paper, is developed the algorithm for design of the gear includes typical steps of analysis and stress calculation of the main components, such as gears, shafts and bearings. Same different calculations, resulting from the special requirements and conditions of the application's exploitations can be also included in mechanical modeling procedure, as a choice. computer program writing in a Visual C++ was also made. The computer program simplifying standard procedure of tedious mechanical computations is also provided. The advantage of the time shortening for complicate reiterations and decreasing of the routine mistakes due to use of computer program is evaluated.
Accelerated life testing has major impact on the success of a ground vehicle development program. Accelerated life testing profile should represent the customer usage so that optimum design can be achieved. A novel approach incorporating finite element analysis and vehicle durability test data into single axis accelerated life test profile generation was developed in this study. The proposed approach was successfully applied to the engine mount bracket of a heavy duty truck engine and it is validated by vehicle and rig tests. The accelerated life testing procedure developed in this study is applicable to many components of ground vehicles. It is possible to test components at high confidence level and low cost with this approach.
Current approaches widely used in fatigue and fracture evaluations of mechanical components are summarized. Metallic alloys, and fatigue and fracture behavior in the absence of environmental effects such as corrosion or elevated temperatures, are considered. Certain shortcomings in the approaches are then discussed, followed by samples of recent work to improve the capabilities to make fatigue and fracture assessments. Finally, future developments that could further enhance those capabilities are suggested.
Fin-angle feedback control is usually used in conventional fin stabilizers, and its actual anti-rolling effect is difficult to reach theoretical design requirements. Primarily, lift of control torque is a theoretical value calculated by static hydrodynamic characteristics of fin. However, hydrodynamic characteristics of fin are dynamic while fin is moving in waves. As a result, there is a large deviation between actual value and theoretical value of lift. Firstly, the reasons of deviation are analyzed theoretically, which could avoid a variety of interference factors and complex theoretical derivations. Secondly, a new device is designed for direct measurement of actual lift, which is composed of fin-shaft combined mechanism and sensors. This new device can make fin-shaft not only be the basic function of rotating fin, but also detect actual lift. Through analysis using stiffness matrix of Euler-Bernoulli beam, displacement of shaft-core end is measured instead of lift which is difficult to measure. Then quantitative relationship between lift and displacement is defined. Three main factors are analyzed with quantitative relationship. What is more, two installation modes of sensors and a removable shaft-end cover are proposed according to hydrodynamic characteristics of fin. Thus the new device contributes to maintenance and measurement. Lastly, the effectiveness and accuracy of device are verified by contrasting calculation and simulation on the basis of actual design parameters. And the new measuring lift method can be proved to be effective through experiments. The new device is achieved from conventional fin stabilizers. Accordingly, the reliability of original equipment is inherited. The alteration of fin stabilizers is minor, which is suitable for engineering application. In addition, the flexural properties of fin-shaft are digitized with analysis of stiffness matrix. This method provides theoretical support for engineering application by carrying out finite element analysis with computers.
In this paper, a method is described for theoretical and experimental studies of a front and rear stabilizer bars used on vehicle steering and suspension systems. Based on the fatigue experimental tests performed on a special test-bed, a complex actuation mechanism from the test bed structure will be analyzed. This mechanism through his kinematic and dynamic structure assures complete conditions for simulating the dynamic behavior in a complex mode of the rear stabilizer bar used on a vehicle steering and suspension structures.
Mammalian zygomatic arch shape is remarkably variable, ranging from nearly cylindrical to blade-like in cross section. Based on geometry, the arch can be hypothesized to be a sub-structural beam whose ability to resist deformation is related to cross sectional shape. We expect zygomatic arches with different cross sectional shapes to vary in the degree to which they resist local bending and torsion due to the contraction of the masseter muscle. A stiffer arch may lead to an increase in the relative proportion of applied muscle load being transmitted through the arch to other cranial regions, resulting in elevated cranial stress (and thus, strain). Here, we examine the mechanics of the zygomatic arch using a series of finite element modeling experiments in which the cross section of the arch of Pan troglodytes has been modified to conform to idealized shapes (cylindrical, elliptical, blade-like). We find that the shape of the zygomatic arch has local effects on stain that do not conform to beam theory. One exception is that possessing a blade-like arch leads to elevated strains at the postorbital zygomatic junction and just below the orbits. Furthermore, although modeling the arch as solid cortical bone did not have the effect of elevating strains in other parts of the face, as had been expected, it does have a small effect on stress associated with masseter contraction. These results are counterintuitive. Even though the arch has simple beam-like geometry, we fail to find a simple mechanical explanation for the diversity of arch shape. Anat Rec, 299:1734–1752, 2016.
In order to improve product performance, this paper provides specific guidance for designers to take product usage information into account in the early design phase. Firstly, the influence of design modification on design process is presented. Secondly, by reviewing some helpful studies, the primary reasons of the design modification occur after prototyping phase is stated. Thirdly, we propose that a user manual can be created before prototyping stage to direct the design activities. We define the design process as 3 levels, function level, task level, and behavior level. At the function level, designers decompose the high-level function into sub-functions until elementary level that all elementary functions are arranged in a pre-determined order. At the task level, designers allocate each elementary function to machine, user, or interactive between the two. At the behavior level, Designers study the interrelationships between user’s behavior and structure’s behavior to examine whether the interactions meet the required performance or not. Finally, the simple case verifies the effectiveness and practicability of the proposed method in this paper.
Abstract One of the basic human needs is having a proper shelter. Due to the rapid population and urbanization growth, there is an escalating demand for affordable housing in Kenya. This necessitates looking for ways to reduce construction costs, particularly for low-income housing group. Concrete-block construction has recently gained significance, however most of the commercially-available block-making-machines are imported and also expensive. Locally-made affordable block-making-machine would render useful in lowering the cost of construction. This project, therefore, was aimed to complete a conceptual design of an innovative undemanding stationary manually-operated concrete-block-machine that molds concrete-blocks at a fraction of a cost in comparison with power-operated options. The target specifications were derived from the customers’ needs data collected during the local workshops’ visits and from the secondary sources, mainly patents. Three design alternatives were developed; alternative design #3 was chosen by the engineering design decision-weighted-matrix and by the drop and re-vote (D&R) method. The originality of this design is essentially in the ejection system: as opposed to many block-making-machines available which ejects blocks instead of the mould, this machine ejects the mould leaving the blocks on the base plate. Mild steel was a material of choice for the machine. A static simulation study on the frame model, which was fixed at the bottom mounting and an overall normal force of 981N or 100 Kg applied at the base plate was done using Engineering Design Software: SolidWorks, 2013 (design and simulation tool). The study included Stress, Displacement, and Strain analysis. Conceptual design of manual-concrete block-making-machine was optimized according to results of simulations, calculations and fundamental engineering design principles. Cost estimation shows that this simple and economical piece of equipment could have a potential in lowering the cost of construction. To ascertain a potential, however, the authors propose further work on prototyping and testing to be carried out. Key words: block-making, concrete, design, machine.
This chapter focuses on the principles that guide the design and construction of robotic systems. The kinematics equations and Jacobian of the robot characterize its range of motion and mechanical advantage, and guide the selection of its size and joint arrangement. The tasks a robot is to perform and the associated precision of its movement determine detailed features such as mechanical structure, transmission, and actuator selection. Here we discuss in detail both the mathematical tools and practical considerations that guide the design of mechanisms and actuation for a robot system.
The following sections (Sect. 4.1) discuss characteristics of the mechanisms and actuation that affect the performance of a robot. Sections 4.2–4.6 discuss the basic features of a robot manipulator and their relationship to the mathematical model that is used to characterize its performance. Sections 4.7 and 4.8 focus on the details of the structure and actuation of the robot and how they combine to yield various types of robots. The final Sect. 4.9 relates these design features to various performance metrics.
In the paper a fragment of research on development of modelling methods of asymmetrical multi-bolted flange connections is presented. The effect of the bolt modelling method in a single bolted joint on both the stiffness characteristics of elements joined in the multi-bolted flange connection and bold forces have been examined. An analysis of the multi-bolted flange connection is carried out for selected models created using the finite element method (FEM). Guidelines for the selection of the bolt modelling method in the case of both the stiffness analysis and the load analysis of multi-bolted flange connections have been pointed out.
Figure 1 shows the design details of a disk sander that is made by Austenitic type 316 steel having σy = 207MPa, σfr=552 MPa (in tension). The critical force on the disk is applied at 100 mm radius. This force is sufficient to develop of a friction torque of 10 Nm, value close to the stalling torque of the motor. The friction coefficient that can be developed between the disk and the object is having a maximum value of 0.6. What is the safety factor for infinite fatigue life?
Fuses in electrical circuits are introduced to protect the systems when subject to unexpected loads. This is achieved through purposely failing a link at a predefined load, thus disrupting the load path. While this technique is well established in electrical and mechanical engineering, extension to civil engineering would require further innovation. The current standards are aimed at designing joints not to fail at a given load. Therefore, designing a joint that will certainly fail at a given load is quite challenging. This paper analyses a tensile bolt group joint to arrive at a stochastic model for predicting the failure load.
In this paper, the mathematical model based on modern design methods of machinery used to optimize the parameters of the two-stage chain transmission system was established. The optimization toolbox of Matlab was introduced as well. Optimization results showed that, the pitches of first and second-stage chains were 19.05 and 25.4 respectively; compared with the original scheme, transmission ratio of first-stage chain decrease from 2.57 to 1.77, while the second-stage increase from 1.0 to 1.45. The number of chain strands of second-stage chain decreased from 2 to 1. The teeth number of the driven sprocket of the first-stage chain decreased also from 59 to 41. Total weight of the sprockets of the chain transmission system decreased from 25.40 kg to 14.84 kg, at least 41.57% material was saved and not less than 50% production cost was reduced. The optimization method is simple, feasible and the optimized parameters are reliable in practice.
As described in the previous chapter, furnaces and boilers are manufactured in a wide range of types and sizes. Regardless of steaming capacity, the steam generation process in any boiler is the same. Heat released in the furnace by the combustion of a fuel is transferred to water in tubes in which steam is formed. Boilers are distinguished one from another by their physical size, the balance between radiative and convective heat transfer from the furnace to the water tubes, the rate of heat release and steam production, the method of separation of the steam and water phases and the operating pressure and temperature of the steam produced.
Power or energy production is improbable everywhere due to various factors. For assorted applications, people depending source of power.This shows the need of transmission of power. Considering power transmission of mechanical drives, mesh type of drives are largely used to maintain the velocity ratio. Among mesh type, gears transmitting the power by means of successive engagement of their teeth. Design of gears either by manually or using computers has become a highly convoluted and comprehensive subject. Therefore, this study present a new method of how the gears can be designed and detailed with computer, previously, highlighting the design process which involves prolong time. A reliable software package developed with a help of Visual Basic 6.0 (VB) provides significant saving time reduces its convolution.
People who have lost a leg have a diminished capacity to complete daily tasks. While prosthetic limbs are not a new field, adjustability of such limbs is proposed to increase the life span of the prosthesis. The increased life span of a prosthetic limb will greatly decrease the cost an amputee has to spend over the years on prosthetics; the need for a replacement will be less. The main objective for the research was to design a low cost, adjustable upper-limb prosthetic leg. The adjustability of the leg allows the user to keep the same prosthesis for a longer period of time as the prosthetic leg is able to adjust to match the growth of the body. The design of the leg allowed for an electric knee, should the user wish to upgrade to one. The leg was designed to focus on strength, natural gait mimicry and promote adjustability of both leg and foot length. The design of the foot and ankle was aimed at simplicity and affordability.
RESUMEN Las transmisiones por tornillo sinfín poseen una baja eficiencia a causa del elevado deslizamiento entre las superficies de contacto del tornillo y de la corona, lo que provoca un elevado coeficiente de fricción. En estas transmisiones la corrección del dentado se realiza sólo en la corona, para ajustar la distancia entre centros o elevar la resistencia de esta, sin embargo, en el cálculo del factor de forma de los dientes no se toma en cuenta, en la literatura consultada, el coeficiente de fricción ni se ha establecido claramente la influencia simultanea de la corrección y la fricción en la resistencia a la fractura de los dientes de la corona. Sobre la base de un nuevo modelo matemático que permite calcular el factor de forma del diente en función de la corrección del dentado y del coeficiente de fricción en el presente trabajo se esclarece la influencia simultanea del coeficiente de fricción de la transmisión y de la corrección del dentado en la corona sin fin en la resistencia a la fractura de los dientes de esta última y se obtienen muy interesantes conclusiones. PALABRAS CLAVE: Coronas sinfín, corrección del dentado, fricción entre los dientes, resistencia a la fractura.
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