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SurfUp Storage Locker Project

MAE 156B Capstone Project, Sponsored by SurfUp

University of California, San Diego - Spring 2020

Who is SurfUp?

SurfUp is a startup company founded and managed by MBAs of UCSD’s Rady School of Management, whose core values are customer-focused and environmentally-friendly. SurfUp has developed an automated surfboard rental station and companion smartphone app. Their aim is to promote hassle-free surfboard accessibility to enthusiastic beginners and seasoned surfers alike. In their pursuit of providing a user-friendly experience for their customer base, SurfUp decided to consult an engineering team to add a functional locker to their rental pods, allowing for convenient storage of personal belongings during surf sessions.

What is our mission?

The engineering team's primary objective is to design and develop a secure storage space that will allow SurfUp users to store their valuables while surfing. In addition to preventing theft, the locker must be made out of materials that can withstand the harsh beach environment. The storage space must also fit within the current design footprint of the pod, as seen in Figure 1. The two secondary objectives are to reduce the power demands of the current locking mechanism and to develop a system that will ensure surfboards always lie in the same place when returned.

The following key components are labeled below in Figure 5. Piano hinges run the length of all four edges, eliminating gaps between the locker walls, effectively boosting the security and structural stability of the system. Cabinet dampers are positioned towards the back of the locker to provide damping to the system. Countersunk magnets that attract to steel brackets are attached to the top of the locker wall to stow the locker in the upright, folded position when it is not in use. A keyed weatherproof cam lock is mounted on the locker door and latches to the frame of the station. The door and locker handles create an accessible, easy-to-use experience.

Figure 3: Prototype without surfboard;

Locker in ready-to-use position

The final design utilizes a fold-out locker mechanism, which allows the locker to reside within the same rack that holds the surfboards. As shown in Figure 2, when a surfboard is in the station, the locker is stowed upright and out of the way. Once the surfboard is rented and removed from the station, the locker can be pulled down using the handle, until the stoppers rest on the support of the rack. Figure 3 displays the locker in its ready-to-use position. In figure 4, the folding locker is seen in a three-position sequence: in stowed upright position, being brought down, and ready-to-use.

Figure 1: SurfUp's current

rental pod model

Main Areas of Focus

1. Functionality: a simplistic, smooth, and quiet system that requires minimal steps, and promotes a comfortable user experience. The storage capacity should accommodate a towel, pair of shoes, keys, phone, and a wallet.

2. Manufacturability: a design that can be replicated and consumer-tested with ease, with minimal costs and customization efforts. At the same time, this focus must follow the primary objective of maintaining corrosion resistance and industry standard weather-proofing.

3. Security: User safety and robustness of the system are must-haves. Our design utilizes the closed environment of the existing SurfUp rental station to deliver the impression of "a lock within a lock."

Final Design Description

Figure 2: Prototype with surfboard;

Locker stowed upright

Figure 6: Successful finger test and best damper solution

Magnets Stow Locker Upright

Figure 4: CAD model of locker being lowered

Figure 5: CAD model of final design with labeled key components

Final Design Intent: Due to manufacturing limitations that resulted from the COVID-19 pandemic, our prototype was created from plywood. We recommend the final design be implemented with anodized 6061 T6 aluminum alloy sheet metal, and integrated into SurfUp's existing rental pod model.

Summary of Performance Results

Cabinet Dampers Promote User Safety

The implementation of cabinet dampers allowed for a slow drop-down speed, diminishing the impact upon contact. This damping feature promotes safety and prevents harm to the locker user’s fingers. As seen in The Finger Test, displayed in Figure 6, the locker drop speed reduces significantly before contacting the fingers, leaving a 2.5cm gap and allowing for sufficient reaction time.

Maximum Capacity Results

Figure 7: Magnets snap locker into upright position

From the theoretical model, it was predicted that the locker would require approximately 22 N of magnetic force to hold it upright. An individual magnet introduces nearly 24.5 N of attraction force. When the locker was tested using one magnet, it did hold as predicted. At the slightest tap, however, it falls down. Two magnets, or 49 N of magnetic force, provides a sufficient amount of force to securely hold the locker in place, while still allowing the user to pull it down without having to exert an uncomfortable amount of effort. It is also enough force that causes the magnets to 'snap' once hitting the angle brackets, making it easy for users to confirm once it reaches its final position.

Figure 8: Static Stress Analysis of the locker and hinges experiencing 60N of force on the lower panel

Using estimations determined by weighing the heaviest items the team could find that would be reasonably expected to be brought to the beach, it was determined that the most likely maximum estimate of force was approximately 20N. To test the system for abuse, a stress analysis was completed for the system with a force of 60N, or three times the expected maximum force. Stress analysis determined that, while the hinges experience the most stress in the system, they nonetheless maintain a factor of safety of 3, even at the heaviest load. Given the high factor of safety, even if someone were to exceed 60N it would be unlikely that the box would break unless truly extreme amounts of weight were placed upon it.

Hardware Demonstration

Video 1: A Walk-Through of some of the technical aspects of the locker

Video 2: A demonstration of standard use of the locker by a consumer

Find more info by reading the Executive Summary, or by exploring the Final Design and Multimedia pages of this website.