Conceptual Design of Modular Chassis Jig of Student Competition Car

Chassis jig is needed to ensure that the welded chassis components does not warp or deform during welding process. Through concept screening and concept scoring, multiple design of chassis jigs is narrowed down to next development process. This study aims to design a chassis jig for the fabrication of student car competition chassis. The desired result of this design process is chassis jig with the ability to manufacture a wide variety of student competition car chassis.

safety. There are several types of chassis, ladder frame, space frame, and monocoque. A lot of student teams apply space frame chassis for their cars. Space frame chassis is chosen due to simpler manufacturability and cost effectiveness.
Space frame chassis are manufactured by welding some of tubing. To ensure accuracy, space frame chassis materials are welded on chassis jig and several fixtures.
Welding fixtures are typically the most common devices used to align and retain the various pieces for welding [1]. Some chassis jig on the market are using steel as their

Research Methodology
This study applied three stages of process as shown at Figure 1. The first stage is to collect all requirement measurement, such as, length, width, and height of car chassis based on technical rules for each competition. As the second stage, we recall that concept selection is the process of evaluating concepts with respect to customer needs and other criteria, comparing the relative strengths and weaknesses of the concepts, and selecting one or more concepts for further investigation, testing, or development [2].
Material selection criteria are limited to ease of manufacturing and assembly process, and rust resistance properties. The third stage is when chassis jig was design and some feature were added.  Further investigated issue needs to be clarified before chosen final concept. Selection criteria are weighted to increase the sensitivity of concept determination as shown in Table 2. The total score for each concept is the sum of the weighted scores, and formulated as:

International Journal of Applied Sciences and Smart Technologies
Here, is the raw rating of concept j for the ith criterion, represents the weighting for ith criterion, is the number of criteria, and denotes the total score of concept j.

Results and Discussion
Chosen concept is combination of concept C and E. Concept CE is constructed by welded square hollow steel as bottom part of frame and slatted arrangement of aluminum extrusion as table top as shown in Figure 2a. From bottom part of frame to table top is raised by another aluminum extrusion. That configuration provide better stability as center gravity is lower. The lower part also useful for storing jigs/fixtures, welding equipment, and power tools that required during chassis fabrication. Figure 2b shows chassis jig with SEM prototype car chassis on top of it. For FS car chassis, some additional jig members were added to support front and back section of car chassis as shown in Figure 2c. Fixtures for holding chassis materials will be design as future work.

Conclusion
Concept CE has been concluded as best concept after several steps. The excellence of Concept CE amongst others are: • Lightweight: using aluminum extrusion as the most component are reducing overall weight • Rust resistant: aluminum is already rust resistant since it already provides oxide film all over the surface.
• Easy to assemble: aluminum extrusion provides tracks that has standardized dimensions and their own accessories such as nuts, bolts and connectors.
process and assembly is just simply as cut and connect. It does not need complex manufacturing process on many machines.
• Modular fixture: lower fixture design are mainly based on aluminum extrusion track design, and the top one are following work piece design, that is, aluminum hollow tube for chassis.
• Rigid enough: aluminum extrusion cross-section is already designed to maintain rigidity along its length. Bigger cross-sectional area provides minimum deflection and maximum rigidity when they are made into a structure.
• Easy to move: since it is already lightweight because half part is using aluminum material, the movement also help by castor wheel.
Note that because this concept using aluminum as top, so it does not provide impact protection. Top surface is only used as planar reference and placing fixtures.