Axial Compressive Strength of Foamcrete with Different Profiles and Dimensions

Lightweight foamcrete is a versatile material; primarily consist of a cement based mortar mixed with at least 20% volume of air. High flow ability, lower self-weight, minimal requirement of aggregate, controlled low strength and good thermal insulation properties are a few characteristics of foamcrete. Its dry densities, typically, is below 1600 kg/m3 with compressive strengths maximum of 15MPa. The ASTM standard provision specifies a correction factor for concrete strengths of between 14 and 42MPa to compensate for the reduced strength when the aspect height-to-diameter ratio of specimen is less than 2.0, while the CEB-FIP provision specifically mentions the ratio of 150 x 300 mm cylinder strength to 150 mm cube strength. However, both provisions requirements do not specifically clarify the applicability and/or modification of the correction factors for the compressive strength of foamcrete. This proposed laboratory work is intended to study the effect of different dimensions and profiles on the axial compressive strength of concrete. Specimens of various dimensions and profiles are cast with square and circular cross-sections i.e., cubes, prisms and cylinders, and to investigate their behavior in compression strength at 7 and 28 days. Hypothetically, compressive strength will decrease with the increase of concrete specimen dimension and concrete specimen with cube profile would yield comparable compressive strength to cylinder (100 x 100 x 100mm cube to 100dia x 200mm cylinder)

Humanoid Localization on Robocup Field using Corner Intersection and Geometric Distance Estimation

In the humanoid competition field, identifying landmarks for localizing robots in a dynamic environment is of crucial importance. By convention, state-of-the-art humanoid vision systems rely on poles located outside the middle of the field as an indicator for generating landmarks. However, in compliance with the recent rules of Robocup, the middle pole has been discarded to deliberately provide less prior information for the humanoid vision system to strategize its winning tactics on the field. Previous localization method used middle poles as a landmark. Therefore, robot localization tasks should apply accurate corner and distance detection simultaneously to locate the positions of goalposts. State-of-the-art corner detection algorithms such as the Harris corner and mean projection transformation are excessively sensitive to image noise and suffer from high processing times. Moreover, despite their prevalence in robot motor log and fish-eye lens calibration for humanoid localization, current distance estimation techniques nonetheless remain highly dependent on multiple poles as vision landmarks, apart from being prone to huge localization errors. Thus, we propose a novel localization method consisting of a proposed corner extraction algorithm, namely, the contour intersection algorithm (CIA), and a distance estimation algorithm, namely, analytic geometric estimation (AGE), for efficiently identifying salient goalposts. At first, the proposed CIA algorithm, which is based on linear contour intersection using a projection matrix, is utilized to extract corners of a goalpost after performing an adaptive binarization process. Then, these extracted corner features are fed into our proposed AGE algorithm to estimate the real-word distance using analytic geometry methods. As a result, the proposed localization vision system and the state-of-the-art method obtained approximately 3-4 and 7-23 centimeter estimation errors, respectively. This demonstrates the capability of the proposed localization algorithm to outperform other methods, which renders it more effective in indoor task localization for further actions such as attack or defense strategies

A Note on Redesign Material Substitution and Topology Optimization in a Lightweight Robotic Gripper

The gripper is required because it is the portion of the robot that makes direct contact with the object being grasped. It should weigh as little as possible without compromising functionality or its performance. This study aims to reconsider the construction of a lightweight robotic gripper by modifying the gripper's materials and topology. Using the finite element (FE) method, several types of gripper materials were evaluated for static stress. On the basis of the results of the FE analysis, the optimal material candidate was chosen using the weighted objective method. Using the Fusion 360 software, the topology of the selected material was then optimized in an effort to achieve the 40% weight reduction’s objective. In addition, the suggested optimized geometry is then fine-tuned so that it can be manufactured as efficiently as possible. The final step in the validation of the robotic gripper's design was stress static analysis. The revised gripper design has a mass of 0.08 kg, a reduction of 94% from the original mass, and a safety factor of 3.67%, which satisfies the desired level of performance for the robotic gripper. Utilizing different materials and optimizing the gripper's topology can significantly reduce the overall mass of a robotic gripper. &nbsp

Brief review on dissimilar welding using cold metal transfer

Hybrid joint configuration nowadays has been an essential process for fabrication in both industrial and construction industry. However, the challenges in welding two varied materials need to consider both metal characteristics since the joint of the different metals from various properties cause the formation of intermetallic compounds (IMCs) layers can cause the failure. Various parameters (i.e; welding current, welding speed) and factors (i.e; materials' thickness and properties) need to be considered when joining two different metals using welding. Common methods use for joining two different metals are friction stir welding, laser welding, resistant spot welding and gas metal arc welding (GMAW). Cold metal transfer method (CMT) is new technique that recently applied for joining dissimilar metal weld especially for thin metals of 0.3∼2.0 mm. Major advantage of CMT is using low power and green technology process. This review provides explanation of common field which applying dissimilar metal welding and discuss the previous related researches with example of different materials being used. This including factors that need to be concerned to produce good welding joint and the current research using cold metal transfer for hybrid joint configuration

Test Load Determination On Composite Standard Malaysian Rubber Constant Viscosity 60 For Earthquake Isolator

This paper describes the test load determination on composite Standard Malaysia Rubber constant viscosity 60 for earthquake isolators. The usage of natural rubber in the development of earthquake isolators for building application has led to the investigation on its mechanical properties such as hardness, elastic modulus and many more. In this study, the mechanical properties of Standard Malaysian Rubber with constant viscosity 60 with various percentage of carbon black were investigated. The main purpose of this study is to implement the usage of Standard Malaysian Rubber as the main substance in the development of earthquake isolators. The nano-indentation was carried out by using Berkovich tips at a constant load with various holding time and it recorded the highest hardness and elastic modulus values and possessed the lowest penetration depth. This test also revealed that the hardness and penetration depth were independent of the holding time. In contrast, the indentation elastic modulus was found to be highly affected by the holding time. By using the nano-indentation test, it can determined that the mechanical properties of Standard Malaysian Rubber, is more cost-effective, non-destructive, and requires small test piece as compared to the conventional technique