Charpy V notch tests – Risks associated with testing with 3 samples

To estimate the risk of brittle fracture of a component in service, Charpy tests are generally carried out on 3 samples at the same temperature. Work done over many years on welded joint fatigue using probability and statistics has shown that to have a good assessment of minimum strength, it is clearly necessary to have a larger number of test results. In order to analyse the risks associated with this practice of 3 samples tested at the same temperature, a series of 17 Charpy impact test results of samples of the same steel plate was chosen. From this series, by translation, 2 series were generated, one with a test of 3 specimens showing acceptable steel and one with a test of 3 specimens showing unacceptable steel. The 3-test method was applied to these series leading to a possible simulation of 12 tests each. It was found that the 3-test practice leads to a risk of error of 30 to 40%. It is also found that the determination of the transition curve of a DH36 steel finally shows that its temperature for a CV of 27 J is of the order of −50 °C whereas the regulations require only −20 °C. In conclusion, a possible improvement of the test procedure is indicated, which is the subject of a study within the framework of the “CCRS rupture and fatigue” working groups of the Société des Ingénieurs Soudeurs (SIS).

The Correlation between Physical Environmental Factors and Fatigue of The Workers at Ship Repair Workshop

Introduction: Fatigue is a body protection mechanism that prevents further detriments and can be recovered after having a sufficient amount of rest. The fatigue undergone by workers is one of the causes of occupational accidents. Fatigue can be triggered by several factors, such as physical environments, for instance, temperature and noise. This research aims to analyze the relationships between the temperature as well as the noise and the work fatigue of the workers at the area of ship repair workshop at PT. X Surabaya. Methods: This research is descriptive observational research that employs the cross-sectional design. The sample of this research, the total population, consists of 32 people. The data is obtained through the temperature measurement by utilizing hygro-thermometer, the noise intensity measurement by utilizing the sound level meter, and the levels of work fatigue measurement by utilizing reaction timer. Those measurements are completed in two different locations, namely the office and the workshop. The strength of the relationships among variables is scrutinized by applying the spearman correlation test by studying the correlation coefficient value. Results: Show that 14 people (43.8%) do not suffer from any fatigue, 15 people (46.9%) suffer from mild fatigue, 2 people (6.2%) suffer from moderate fatigue, and 1 person (3.1%) suffers from severe fatigue. The fatigue is mostly undergone by the workers exposed to the overheat temperature, that is as many as 18 people (56.2%) and by those who are exposed to noise, which are 15 people (46.9%). Conclusion: There is a moderate relationship between the temperature and the fatigue (p=0.519). Meanwhile, the noise (p=0.688) has a strong relationshipship with the fatigue undergone by the workers at the area of ship repair workshop at PT. X Surabaya. Keywords: noise, ship reparation, temperature, work fatigue

The Correlation between Physical Environmental Factors and Fatigue of The Workers at Ship Repair Workshop

Introduction: Fatigue is a body protection mechanism that prevents further detriments and can be recovered after having a sufficient amount of rest. The fatigue undergone by workers is one of the causes of occupational accidents. Fatigue can be triggered by several factors, such as physical environments, for instance, temperature and noise. This research aims to analyze the relationships between the temperature as well as the noise and the work fatigue of the workers at the area of ship repair workshop at PT. X Surabaya. Methods: This research is descriptive observational research that employs the cross-sectional design. The sample of this research, the total population, consists of 32 people. The data is obtained through the temperature measurement by utilizing hygro-thermometer, the noise intensity measurement by utilizing the sound level meter, and the levels of work fatigue measurement by utilizing reaction timer. Those measurements are completed in two different locations, namely the office and the workshop. The strength of the relationships among variables is scrutinized by applying the spearman correlation test by studying the correlation coefficient value. Results: Show that 14 people (43.8%) do not suffer from any fatigue, 15 people (46.9%) suffer from mild fatigue, 2 people (6.2%) suffer from moderate fatigue, and 1 person (3.1%) suffers from severe fatigue. The fatigue is mostly undergone by the workers exposed to the overheat temperature, that is as many as 18 people (56.2%) and by those who are exposed to noise, which are 15 people (46.9%). Conclusion: There is a moderate relationship between the temperature and the fatigue (p=0.519). Meanwhile, the noise (p=0.688) has a strong relationshipship with the fatigue undergone by the workers at the area of ship repair workshop at PT. X Surabaya. Keywords: noise, ship reparation, temperature, work fatigue

The Design and Manufacture of a Multilayer Low-Temperature Protective Composite Fabric Based on Active Heating Materials and Passive Insulating Materials

Based on active heating materials (the phase change microcapsules (microPCMs)) and passive insulating materials (SiO2 aerogel), a new-type multilayer low temperature protective composite fabric (MPF) was designed and manufactured to meet the demands of protection and operation in a short time under a low-temperature environment. Results showed that the MPF consisted of three layers including the fabric layer, the microPCM function layer, and the SiO2 aerogel thermal insulation layer. The differential scanning calorimeter (DSC) results demonstrated that the phase transition enthalpy of the composite was 96.2 J/g during the cooling process. The low-temperature resistance and thermal insulation performance at −50 °C were investigated. The results also demonstrated that the low-temperature resistance time of the MPF was 660 s and the power consumption of the MPFs needed to maintain 37 °C for 10 and 20 min were 629 J and 1872 J, respectively. Compared with the microPCM function layer and the thermal insulation layer, which have the same thickness as the MPF, the low-temperature resistance time of the MPF was prolonged for about 2 and 3 min, respectively. The MPF could provide effective protection of the low-temperature work in a short time and could be applied as potential materials in low-temperature protection.

Piezosurgery in Hallux Valgus Correction: Distal Linear Osteotomy Operative Technique Using Piezoelectric Tools

Purpose Piezoelectric and ultrasonic vibrations have been used to cut tissues for three decades, in particular, in periodontics. The increasing use of piezosurgery is based on its clinical advantages such as selective cutting, precision, and low-temperature work rates. The authors applied this concept to a new operative field, the foot and ankle pathology and surgery, such as hallux valgus corrective distal linear osteotomy. Methods The osteotome equipped was the Surgysonic Moto-II model (Esacrom, Imola, Italy), a system recently developed for cutting bone withmicrovibrations. Tips used in author’s case series were a high-efficiency five teeth piezoelectric saw and a high-efficiency flat scalpel shaped on three edges. Operative technique is described. Discussion and Conclusion Piezoelectric techniques were developed in response to the need for great precision and safety in bone surgery that was availavle with other manual and rmotorised instruments. Piezo-technology allows minimally-invasive and percutaneous surgery, with reduced trauma on periostium, bone, and soft tissues, reduced healing time of the osteotomy due to the absence of bony necrosis and debris formation and major precision.