Final Design

The Final Design: Plywood Prototype of the Side Folding Locker

Figure 2: Working model damping simulations In-ideal performance without damping Ideal performance with damping

Figure 3: Testing falling locker using damper in different locations

Figure 1: From left to right: Front view, Isometric view, Side view, Isometric view in ready-to-use position

Key Design Component: Damping Mechanism

Since the design is intended to be implemented with entirely aluminum and stainless steel materials, it will carry significant momentum when dropping down. Such momentum has the potential to harm users and decrease the lifespan of locker. Performing simulations in Working Model 2D provided insights on the amount of force incident upon the stoppers as the locker drops down, and thus how much damping is required to reduce the impact. The simulations with and without damping are shown below.

Test 1: Not enough damping Test 2: Over-constrained Test 3: Adequate Damping

Slams down, late contact with damper Does not fully compress the damper Smooth motion, fully compresses damper

Figure 4: Cabinet door dampers

placed on bottom corner and side of locker

Key Design Component: Magnets to Stow Locker Upright

Cabinet door dampers were chosen to provide damping to the system, because they are highly adjustable in terms of both positioning and damping effect. When the cabinet door dampers were implemented into the plywood prototype, several locations and amounts of dampers used were tested, including the three tests shown below. The ideal solution is shown in test 3 of Figure 3, in which the dampers create a smooth and controlled motion, effectively slowing down the terminal velocity and minimizing impact. Figure 4 depicts close ups of the locations the cabinet dampers were stationed.

To hold the locker in the upright position, a combination of rare earth magnets and steel angle brackets are located on the top of the structure (Figure 5). The magnets are countersunk, which allowsthem to be directly attached to the top panel with a flat head screw. The brackets are attached to the top of the rack, also with a flat head screw. Two magnets were used (each introduces nearly 24.5 N of attraction force), which is twice the required magnitude required to hold the locker.

Figure 5: Countersunk magnets and brackets they attach to

Key Design Component: Weatherproof Mechanical Lock

As shown in figures 6 and 7, a weatherproof cam lock was chosen to lock the door closed once user put their belongings inside. Under the harsh coastal environment, the weatherproof cam lock remains functional and overcomes devastating factors such as sand, salt water and ultraviolet light. When the key is not inserted, stainless steel shutter blocks sand, water and dirt from getting into the lock. In addition, the lock consists of only 5 major components, making it easy to assemble and less likely to malfunction.

Figure 6: Cam lock, outside view Figure 7: Cam lock, inside view

Key Design Component: Piano Hinges

Piano hinges, which are hinges that run the entire length of the two panels being connected, were used throughout the system. The piano hinges were selected for the locker due to the high level of security that they offer with no gaps between locker walls, as shown in Figure 8. As detailed in the SolidWorks Static Analysis, the majority of the stress in the locker occurs in the hinges. The piano hinges allow the stress to be well-distributed along the length of the locker, avoiding points of high stress concentration at any given place in the design. Furthermore, the piano hinges are quite thin, enabling the locker to be folded upright without adding undesirable bulkiness to the system.

Figure 8: Piano hinges

Additional Design Components

As shown in Figure 9, brackets were implemented on the top of the from panel in order to prevent theft. Once the user closes the door, this bracket prevents another person from lifting the handle and taking items from inside. User safety and comfort is prioritized in the design process of the SurfUp locker project. Fillets and round up corners are ubiquitous in metal components as sharp edges are dangerous and can potentially rust over time. To deliver a secure, safe, and polished product, our team chose rounded brackets.

Figure 9: Rounded anti-theft brackets

For the locker handle, we attached a metal rod to the far corner of the top panel (Figure 10). Placing the handle as far from the hinge as possible maximizes the moment that the user can apply, which makes it the easiest location from which to lift the locker. The rubber grips allow the user to comfortably grip the handle when lifting the locker up and down.

Figure 10: Locker handle

Due to extremely restrictive limitations, including lacking access to a machine shop, the prototype possesses several unideal gaps and misalignments, which is apparent in some images. However, in the intended final design, gaps and flushes are minimized throughout the system to promote structural integrity.

Key Design Recommendation: Anodized Aluminum Locker Walls

Using SolidWorks Simulation, stress analysis was conducted to predict the maximum load the locker can take made from various material types, including several aluminum and stainless steel alloys. A factor of safety greater than 20 was calculated for 6061 T6 aluminum alloy, indicating the material's adequacy in terms of deformation resistance and sufficient ability to withstand the expected load. Seen below is a depiction of the analysis performed in SolidWorks. Furthermore, anodized aluminum is recommended for it's corrosion resistance and thus suitability for marine environmental conditions.

SolidWorks Analysis: Isometric view of the lock box under 20N of Force. The highest stress points on the hinges and on the aluminum sheet are marked with probes