Crankshaft failure analysis of a boxer diesel motor

This paper reports a failure mode analysis of a boxer diesel engine crankshaft. Crankshafts are components which experiment severe and complex dynamic loadings due to rotating bending combined with torsion on main journals and alternating bending on crankpins. High level stresses appear on critical areas like web fillets, as well as the effect of centrifugal forces and vibrations. Since the fatigue fracture near the crankpin-web fillet regions is one of the primary failure mechanisms of automotive crankshafts, designers and researchers have done the best for improving its fatigue strength. The present failure has occurred at approximately 2000 manufactured engines, and after about 95,000 km in service. The aim of this work is to investigate the damage root cause and understand the mechanism which led to the catastrophic failure. Recommendations for improving the engine design are also presented.info:eu-repo/semantics/publishedVersio

New approach for analysis of complex multiaxial loading paths

Experimentally, it has been proven that the stress level needed to cause fatigue failure in pure shear is less than the axial one. This fact has led to consider a stress scale factor between shear and axial stress in order to reduce different applied stresses to the same shear stress space or principal stress space to facilitate the yielding analysis or fatigue damage evaluations. In this way most of multiaxial fatigue models use a stress scale factor to consider the fatigue damage contributions from the axial and shear stress components regarding the material strength degradation. Much efforts were made to quantify the effective shear and axial stress amplitudes under a three-dimensional stress state, however, the combined damage resulted from those amplitudes have been reduced to a constant value. In some cases, the approaches used proved to be inadequate, leading to compute the same equivalent stress for different loading paths with different fatigue lives. In this work it is performed a series of multiaxial fatigue tests on a high-strength steel in order to determine the multiaxial fatigue strength under proportional and non-proportional loading conditions. A stress scale factor function was mapped based on the experimental results using as arguments, the axial stress amplitude and the stress amplitude ratio, which has proven to be sensitive to the loading path nature. Using the stress scale factor surface an equivalent shear stress was defined and it was used in the fatigue life correlation. Results indicate that the stress scale factor (ssf) is not a constant value and it is strongly dependent on stress amplitude level and loading path shape. The equivalent stress was successfully applied to proportional and non-proportional loading paths with satisfactory results.info:eu-repo/semantics/publishedVersio

Relating organizational knowledge with ISO 9001: 2015: An empirical approach

In a business market environment highly marked by competition, standardisation has proven distinctive in answering continuous challenges. Thus, organisations have been investing in obtaining ISO certifications, being "ISO 9001 – Quality Management System" among the most popular. The present empirical study aims to discover what is, in the opinion of managers expressed by their answers to the questionnaire, the relationship between the implementation of Knowledge Management practices, the Quality System and Organizational Performance while verifying if the introduction of Knowledge Management principles in the Standard ISO 9001 has affected the company's overall organisational performance. The proposed analysis methodology is supported by applying a questionnaire to 36 Portuguese Small and Medium Enterprises sample. The investigation results allowed us to infer that, in the managers' opinion expressed by the answer to the questionnaire, Knowledge Management acts as a mediator between the Quality System and performance while not directly influencing organisational performance. Within the companies studied, holders of the certification ISO 9001, through the application of Knowledge Management practices, show improvements in the management of the Quality System, with a consequent increase in organisational performance.info:eu-repo/semantics/publishedVersio

Stadion Olahraga Di Woloan-tomohon. Hi-tech Architecture

Olahraga adalah salah satu kegiatan manusia untuk menjaga kebugaran tubuh. Pada era sekarang olahraga pun mulai diminati kembali. Dapat dilihat dari perkembangan yang ada dibeberapa daerah, salah satunya di Kota Tomohon, Kota ini memiliki banyak potensi olaharaga untuk dikembangkan namun sayangnya fasilitas yang ada dalam daerah ini masih belum memadai, kurangnya fasilitas daerah menjadikan animo masyarakat mulai menurun terhadap olahraga. Perancangan Stadion Olahraga di Kota Tomohon dapat menjadi satu wadah untuk menjawab kekurangan yang ada dalam daerah ini. Dalam penulisan ini kajian diawali dengan mempelajari tentang Stadion Olaharaga tersebut, standar-standar perancangan dan perencanaan bangunan Stadion Olaharaga, pengertian dan ciri-ciri High Tech Arsitektur, serta studi banding beberapa Stadion yang telah ada. Dilakukan juga tinjauan mengenai Kota Tomohon terlebih untuk lokasi yang berada di Woloan. Pendekatan perancangan arsitektural dilakukan dengan konsep High Tech Arsitektur. Selain itu dilakukan pendekatan fungsional, kinerja, teknis, dan kontekstual. Sebagai kesimpulan, program ruang sangat diperlukan, serta gambar-gambar 2 dimensi dan 3 dimensi sebagai ilustrasi desain

Cutis Laxa

Introdução:A cutis laxa é uma doença rara do tecido conjuntivo provocada por alterações da elastina. Caracteriza-se por pele sem elasticidade, flácida, mole e enrugada, dando aos doentes um aspecto envelhecido; o envolvimento sistémico é variável. Existem formas hereditárias e adquiridas. Relato de Caso: Lactente do sexo masculino, de seis meses de idade, no qual na sequência de internamento por bronquiolite é notado fenótipo muito sugestivo de cutis laxa, tendo o exame histopatológico cutâneo confirmado o diagnóstico. Discussão Clínica: O caso parece relevante, pela raridade da doença e por apresentar fenótipo sugestivo de cutis laxa do tipo autossómico recessivo, mas com evolução clínica mais característica da forma dominante, com melhor prognóstico

Digital human modeling (dhm) for computer-aided ergonomics analysis in the horticulture industry

In Indonesia, the production of water spinach increased by 9,24% from the last year, which was reasonable because water spinach was one of the most sought-after and popular types of vegetables. The farmers have exposure risk factors of work-related musculoskeletal disorders (MSDs) owing to poor watering of plant workstations using manual methods. This journal aims to explore the application of computer-aided ergonomic analysis and digital human modeling techniques in optimizing the workstations of farmers in water spinach plantations. This paper compares ergonomic scores for body posture farmers before and after improvement. Improvement was done by replacing the manual ball valve with motor operated valve (MOV), controlled (opens and closes) by farmers’ phones. Before and after improvement, body posture farmers are converted to digital human modeling and analyzed by CATIA and RULA analysis tools. The result of this paper comparing before and after improvement results in a percentage reduction in RULA Scores of 75% from a 4 to 1 value

Transient Thermal Stress Prediction Due To Flow of Coolant Through Hot Pipe

Transient thermal stresses in pipe wall due to coolant turbulent flow through pipe are investigated in this study with transient isothermal hot boundary in the external pipe radius. Three Different values of Reynolds are tested (3000, 5000 and 8000). Finite volume method was used to calculate the velocities and temperatures fields in the working fluid (air). Thermal resistance method was used to calculate the transient temperature distribution in the pipe wall and then the transient thermal stresses were calculated. Minimum thermal stress was located nearly in the mid plane of the pipe

A New Prototype for Automatic Identification of Stone Block Internal Structure

: Nowadays, the inner shape and economic viability of a stone block is dependent on the skill and experience of the “expert” that makes predictions based on external observations. This actual procedure is an extremely high empirical method, and when it fails, substantial work, time, and money is wasted. At present, researchers are committed to developing models to predict the stone block internal structure based on non‐destructive tests. Ultrasonic tomography and electrical resistivity tomography are the tests that best fit these objectives. Trying to improve the existing procedures for collecting stone information and data exporting, a novel approach to perform both tomographies is proposed in this paper. This novel approach presents sound advantages regarding the current manual procedure: namely, (i) high accuracy due to a new automatic positioning system; (ii) no need for highly skilled operators to process measurements; (iii) measurements are much easier to derive, and results are quickly delivered. A comparison between the new automatic process and the current manual procedure shows that the manual procedure has a very low accuracy when compared to the new developed automatic system. The automatic measurements show extremely significant time savings, which is a relevant issue for the future competitiveness of the stone sector

Evaluation of the AZ31 cyclic elastic-plastic behaviour under multiaxial loading conditions

Components and structures are designed based in their material’s mechanical properties such as Young's modulus or yield stress among others. Often those properties are obtained under monotonic mechanical tests but rarely under cyclic ones. It is assumed that those properties are maintained during the material fatigue life. However, under cyclic loadings, materials tend to change their mechanical properties, which can improve their strength (material hardening) or degrade their mechanical capabilities (material softening) or even a mix of both. This type of material behaviour is the so-called cyclic plasticity that is dependent of several factors such as the load type, load level, and microstructure. This subject is of most importance in design of structures and components against fatigue failures in particular in the case of magnesium alloys. Magnesium alloys due to their hexagonal compact microstructure have only 3 slip planes plus 1 twining plane which results in a peculiar mechanical behaviour under cyclic loading conditions especially under multiaxial loadings. Therefore, it is necessary to have a cyclic elastic-plastic model that allows estimating the material mechanical properties for a certain stress level and loading type. In this paper it is discussed several aspects of the magnesium alloys cyclic properties under uniaxial and multiaxial loading conditions at several stress levels taking into account experimental data. A series of fatigue tests under strain control were performed in hour glass specimens test made of a magnesium alloy, AZ31BF. The strain/stress relation for uniaxial loadings, axial and shear was experimentally obtained and compared with the estimations obtained from the theoretical elastic-plastic models found in the state-of-the-art. Results show that the AZ31BF magnesium alloy has a peculiar mechanical behaviour, which is quite different from the steel one. Moreover, the state of the art cyclic models do not capture in full this peculiar behaviour, especially the cyclic magnesium alloys anisotropy. Further, an analysis is performed to identify the shortcomings inherent to the actual cyclic models in the capture of the magnesium alloys cyclic behaviour. Several conclusions are drawn