The objective of this study is to identify the behavior of the car suspension components subjected to road surface contours. Strain signals were measured by installing a strain gauge at the critical area of the coil spring and lower arm. The car was driven on a flat and rough road surface with speeds of 30-40 km/h and 10-20 km/h, respectively. According to the fatigue life assessments based on the strain-life approach, it was found that when the car was driven on the rough road, the components received higher stresses, contributing to a shorter fatigue life. The fatigue life of the coil spring when being driven on the rough road was 1,248 cycles to failure, which was more than 14 times shorter when being driven on the flat road, with 19,060 cycles to failure. Meanwhile the fatigue life of the lower arm being driven on the rough surface was 3,580 cycles to failure, which was almost 3,328 times shorter when being driven on the flat road, with 11,914,000 cycles to failure. The useful life of the coil spring was more than 625 times lower than the lower arm when driven on the flat road, whereas when driven on the rough road, the useful life of the coil spring was almost 3 times lower than the lower arm. In conclusion, the coil spring will fail more than 2 times faster than the lower arm. This is because the contour of the road surfaces provide a vertical load, directly working the coil spring which reduces the load vertically, while the lower arm functions to hold the load when turning.

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The purpose of this work was to predict the fatigue life of the AISI 1513 carbon steel due to the strains measured at a vehicle's lower arm. The strain signals were acquired using a strain gauge installed at the lower arm, and then the car was driven at various road surfaces. On the smooth road surface, the car was driven at a speed of > 70 km/h and on the rough road surface, at a speed of < 20 km/h. The results show that when the vehicle was driven on the rough road, the lower arm received higher stress, which provided a shorter fatigue life. The contour of the road surfaces provided a vertical load, directly working the lower arm and reducing the load vertically. The fatigue life for the rough road surface was 13,050 cycles to failure. This value was 91,195% lower than the fatigue life on the smooth road surface.

This study aims to determine the effect of road surface contours to the fatigue life of an automotive coil spring. A strain gauge was affixed at the critical point based on the stress distributions. The vehicle passed smooth and rough roads with the speeds above 30 km/h and less than 20 km/h, respectively. The strain signals obtained were analyzed using the Coffin-Manson, Morrow, and Smith-Watson-Topper models. According to the analysis, when the vehicle passed the rough road, the coil spring received a higher stress leading to a shorter fatigue life, of 1,284 cycles to failure. This value was 526 % lower compared to the smooth road because it consisted of bumps and holes.

Objective: This study aimed to explore the potential of brown algae (Padina sp) by measuring its compressive and tensile strength as a preparation step for making standardized dental impression materials from sodium alginate Padina sp. Material and Methods: This study was a quasi-experimental study with one-shot case design. Brown algae were taken from the waters of Punaga and Puntondo, Takalar. Sodium alginate was extracted from algae then mixed with other compositions to form alginate impression material. Compressive and tensile were tested using the Point Load Test. impression material. Compressive and tensile were tested using the Point Load Test. Results: Compressive strength of impression material made of Padina sp was higher than that of standard impression material with pressure mean 0.011 Mpa and 0.009 Mpa. The mean tensile strength measurement was 0.003 Mpa. Conclusion: Mean compressive and tensile strength of impression material made of Padina sp were still relatively weak.