DRAFT: This module has unpublished changes.

Mechanical Engineering Calculations

 

Lid Pull Force Calculations

 

In order to ensure that the compartments were easy to open for a user with limited hand strength, an analysis of the chosen design was performed.

 

Lid Opening Force Free Body Diagram

 

The equations used to figure the theoretical force required to open a lid, based on the designed compartments, is as follows. There is the assumption that the moment caused by friction within the brass hinge is negligible. We also neglected the weight of the screws and the magnets because their total weight was less than an half of an ounce.

 

 

Therefore, we were confidently able to confirm that the force to open the lids would be under the 4 lb maximum as outlined in our device specifications.

 

DRAFT: This module has unpublished changes.

Structure Durability and Strength Analysis

 

The CAD model of the device was created in a three dimensional modeling program call SolidWorks. Within this software is the capability of entering in the materials used and analyzing the strength of various parts of the structure before the structure is built. Below are the results of that analysis. The essential information gathered from these graphics is that the factor of safety was at least 4 times the amount required of the device outlined in the device specifications. 

DRAFT: This module has unpublished changes.
DRAFT: This module has unpublished changes.

Also given by SolidWorks, based on the device structure without the electrical components, is as follows:

 

Mass properties of Finaldesign_assembly2

     Configuration: Default

     Coordinate system: -- default --

 

Mass = 5.79 pounds

 

Volume = 160.93 cubic inches

 

Surface area = 1805.07 square inches

 

Center of mass: ( inches )

X = 5.59

Y = 1.84

Z = -5.16

 

Principal axes of inertia and principal moments of inertia: ( pounds * square inches )

Taken at the center of mass.

Ix = (1.00, -0.02, -0.10)   Px = 79.46

Iy = (-0.10, -0.01, -1.00)   Py = 98.54

Iz = (0.02, 1.00, -0.01)   Pz = 150.24

 

Moments of inertia: ( pounds * square inches )

Taken at the center of mass and aligned with the output coordinate system.

Lxx = 79.65  Lxy = -1.16 Lxz = -1.80

Lyx = -1.16  Lyy = 150.21 Lyz = 0.74

Lzx = -1.80  Lzy = 0.74 Lzz = 98.37

 

Moments of inertia: ( pounds * square inches )

Taken at the output coordinate system.

Ixx = 253.79  Ixy = 58.59   Ixz = -169.06

Iyx = 58.59    Iyy = 485.78 Iyz = -54.43

Izx = -169.06 Izy = -54.43  Izz = 299.23

DRAFT: This module has unpublished changes.