Validity and reliability of a questionnaire to investigate people prone to accidents in different industries.

Objectives. In recent years, workplace accidents have imposed a considerable cost on industries. Accident proneness is one of the most influential factors known to cause unsafe behaviors and occupational accidents. Therefore, the present study investigated the validity and reliability of the accident proneness questionnaire in industries. Methods. The questionnaire was developed to measure accident proneness in industries - the developed instrument was distributed in East Azarbaijan industries (1100 questionaries). Content validity, confirmatory factor analysis and exploratory factor analysis were used to examine the construct validity, and Cronbach's α and the test-retest method were used to examine the reliability and reproducibility of the instrument. Results. In the face validity section, the impact score of all items was determined to be >1.5. In the content validity section, the content validity index (CVI) and the content validity ratio (CVR) were higher than the standard value of 0.42. The Cronbach's α coefficient for all dimensions was 0.914. Conclusion. The findings of the study show that the accident proneness questionnaire in industries has acceptable validity and reliability, and can be used as a comprehensive, practical, robust and reliable instrument to investigate the accident proneness of different industries.

Mechanical Anisotropy and Surface Roughness in Additively Manufactured Parts Fabricated by Stereolithography (SLA) Using Statistical Analysis.

In this study, the degree of mechanical anisotropy was investigated through tensile testing of specimens built in different orientations and designed according to the ASTM D638 standard. The mechanical properties that were evaluated include Young's modulus, ultimate tensile strength (UTS), and percentage elongation. Additionally, physical properties, such as mean surface roughness (Ra), density and dimension of the cross-sectional area, were also measured. These properties were then compared with the available standard data to see how SLA performs comparing to the traditional manufacturing methods. The obtained modulus of elasticity and UTS values of the printed samples were 2481 ± 50 MPa and 51.9 ± 1.3 MPa respectively, which were very similar to the standard data (2550 and 52 MPa, respectively) as provided by the material suppliers. The percentage elongation values (4.8% ± 0.4%) were a bit lower than the expected value of 6%. However, the surfaces of all the printed samples were quite smooth, with a surface roughness range of 2.28 ± 0.59 µm. A design of experiments was created to study the influence of the independent variables such as build orientation and angular orientation on the mechanical properties. Extensive statistical analysis, using the Taguchi method and analysis of variance (ANOVA), was performed to examine the effect of these independent variables on the mechanical properties. The SLA printed parts can be classified as isotropic since the build orientation and the angular orientation did not have a statistically significant impact on the mechanical properties. The effect of aging on the mechanical properties was also evaluated and it shows that the specimens that had been aged for a longer time resulted in superior mechanical properties. For example, the UTS increased from 24 to 54 MPa when the sample aligned parallel to the XY plane was aged from 1 week to 6 months, respectively. This significant increase implies that aging has a substantial effect on the mechanical properties of the parts fabricated by stereolithography. The resin used for this study, Visijet Sl Clear, produced very consistent mechanical properties in different directions.