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by: Kyle Will IV


Kyle Will IV
GPA 3.67

John J. Jr Mecholsky

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John J. Jr Mecholsky
Class Notes
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This 9 page Class Notes was uploaded by Kyle Will IV on Friday September 18, 2015. The Class Notes belongs to EMA 4714 at University of Florida taught by John J. Jr Mecholsky in Fall. Since its upload, it has received 9 views. For similar materials see /class/206739/ema-4714-university-of-florida in Materials Engineering at University of Florida.




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Date Created: 09/18/15
TRIZ Concepts 1 Con ict 7 Maximize Strength Minimize Length of stationary object Our product must have high strength The width should be as small as possible so it does not interfere with transporting the laptop Inventive solutions Dynamics Spheroidality Mechanics Substitution and Copying Implementing Inventive Solution of spheroidality We propose using a corrugated shape for a greater section modulus This allows us to keep high strength without resorting to a large width 2 Con ict Maximize Strength Minimize Shape Our product must have high strength The product should not alter the shape of the laptop so as to be unobtrusive as possible to the user It should conform to the shape of the laptop Inventive solutions Preliminary action Flexible Shells and Thin Films Parameter Changes and Composite Materials Implementing Inventive Solution of exible shells and thin lms We propose using a material with a high elastic modulus for rigidity on top of a material with a foamlike characteristics for greater distribution and absorption of kinetic energy 3 Con ict 7 Maximize Strength Minimize Quantity of Object Our product must have high strength The object should be made with as little material as possible so that it can be inexpensively produced Inventive solutions Pneumatics and Hydraulics Preliminary Action Cheap Shortliving objects Implementing Inventive Solution of pneumatics and hydraulics Use a gel to distribute kinetic energy resulting from an impact 4 Con ict 7 Maximize Durability Minimize Quantity of Object Our product must be durable and long lasting However it must not be made up of so many materials that it is expensive to produce Inventive Solutions Local quality parameter changes porous materials Implementing inventive solution of porous materials Use a honeycomb matrix to distribute the force while minimizing the weight The repeating hexagonal pattern is a very strong design that is found in nature e g bee hives 5 Con ict Maximize Strength Minimize Quantity of Object Our product must have high strength The object should be made with as little material as possible so that it can be inexpensively produced Inventive solutions Pneumatics and Hydraulics Preliminary Action Cheap Shortliving objects Implementing Inventive Solution of preliminary action Prestress the material in a way that impacts to the surface alleviate stress already present in the material This could be done by stressing the material in the opposite way it would be stressed when impacted by an object 6 Con ict Maximize Strength Minimize Quantity of Object We want to maximize the strength of our product Designing our product to be practically indestructible is possible however we do not want it to be made up of a lot of material which would weigh too much and take up too much space These results would interfere with our customer requirements that our product be unobtrusive Inventive Solutions Pneumatics preliminary action cheap shortliving object Implementing inventive solution of cheap short living objects Design the screen covering to be replaceable so that when it cracks it can be easily replaced Have it be user replaceable with no tools necessary 7 Con ict 7 Maximize Durability Minimize Weight We want to maximize the durability of our product while minimizing the weight The product must be usable for a long time but not weigh much Inventive Solutions Universality Cheap short living objects periodic actions partial or excessive actions Implementing inventive solution of universality When the laptop is in use the product protects the LCD screen When it is not in use it is rotated around to protect the back of the LCD when the whole laptop is closed 8 Con ict 7 Maximize Strength Minimize Quantity of Object Our product must have a high strength The object should be made with as little material as possible so that it can be inexpensively produced Inventive solutions Preliminary action asymmetry pneumatics and hydraulics Implementing inventive solution of pneumatics and hydraulics Our product could include an air bag that would in ate upon sensing an impact much like an air bag in a car would This would most likely function best on the outside of the screen with a thin layer of sensors that would detect the impact a split second before the air bag would in ate 9 Con ict Maximize Strength Minimize Object complexity Our product must have a higher strength However it must not be so compleX that it would have many parts that could each result in an individual failure Implementing inventive solution of Self service Use a material that heals itself when scratched such as the selfhealing polymers used in new car clear coats Even with a serious scratch this would not require replacing the screen only waiting a short time for the screen to fill in the crack on its own 10 Con ict 7 Maximize Strength MinimizeVolume 0f Stationary Object Our product must have high strength However it must not take up a large volume because that would hinder the portability of the laptop Inventive solutions Preliminary antiaction spheroidality another dimension Implementing Inventive Solution of another dimension Use a lamellar structure like bulletproof glass made of alternating layers of rigid material and a gel adhesive to protect against impact forces Materials Selection Analysis Pugh Analysis An unprotected laptop was selected as the datum for our Pugh analysis because there are no competing products on the market The unprotected laptop had all 0 values as the baseline The preliminary action design consisted of prestressing a covering A force would have to overcome the stress already present in the covering before it could affect the LCD This design is awed because it does not provide shock absorbance The corrugated design would use a corrugated shape to increase the section modulus ofthe covering This design also lacks shock absorbance and the corrugated shape bends easily along a certain axis The corrugated shell would be light but it would take up a lot of space More specifically it would increase the thickness of the laptop substantially The end user would be dissatisfied with a product that effectively doubled the thickness oftheir laptop The shells and thin lm design consists ofa stiff material over a foamlike material The stiff material would distribute the impact force over the foamlike material The foamlike material would provide shock absorbance This design offers the most protection to the LCD A layered structure minimizes the increase in thickness of the laptop This design was selected because it scored the highest in our Pugh analysis as seen in Table 1 Preliminary Shells and Action thin Film In service the hard outer shell and the shock absorbing layer will be attached to the LCD while the transparent screen protector will sit several millimeters off of the LCD as shown in Figure 2 Hard Outer Shell CD Shock Absorbing Layer Transparent Screen Protection Figure 2 Concept Design Performance Index Rigid Material Hard Outer Shell and Transparent Screen Protection Both the hard outer shell and the transparent screen protection have similar requirements The main difference is that the screen protection must be transparent so that it does not hinder the user s view ofthe LCD The hard outer shell has no such requirements as it could even be painted or made aesthetic by other means Forthe rigid material our objective function is to minimize weight m A t p 1 where m is the mass A is the cross sectional area tis the thickness and p is the density of the material Our constraint is the design requirement that the material must not de ect so much that it comes in contact with the LCD causing it to break We treat the rigid material as a hollow shell resulting in the following de ection equation 2 5 0079 b P E t3 2 Where 6 is deflection at the center b is the longest dimension P is the force applied E is Young s modulus of the material tisthe thickness Solving for the free variable tresults in the equation t 007913 b23 PlS E13 613 Eliminating free variables in the objective function results in the final equation 007913 b23 P13 mzA E13 513 39p 4 13 Pl0079 3 13 Ay 5 E13 M1 7 5 p Foamlike Material Shock Absorbing Layer The foamlike material was chosen to reduce the maximum force experienced by LCD during the collision Force during a collision can be represented by the equation mAv At 7 Reducing the change in velocity and increasing the duration ofthe collision will F reduce the maximum force experienced by the LCD Reducing the change in velocity can be done by using a viscoelastic material Viscoelastic materials do not quickly return to their original shape after they have been deformed Collisions involving viscoelastic materials have small coef cients of restitution This results in a loss of kinetic energy and smaller values for Av which reduces the force The duration ofthe impact can be increased by using thicker and softer materials to cause a more gradual deceleration ofthe object that is colliding with the laptop The degree of softness of a material is characterized by its compression modulus G The foamlike material can not be too thick or it will become obtrusive when placed on the laptop It was decided that 1 centimeter would be the maximum allowable thickness This maximum thickness limits the acceptable values for G lfthe material is too soft it will bottom out and the force experienced by the LCD will spike The optimum value for G depends on the collision It was decided that a 6 kg object traveling at 20 mph 894 meters per second would be used as the basis for our design This value is equivalent to the weight and velocity of a heavyweight boxer s punch We feel that this is a good prediction ofthe maximum force most laptops would ever experience The kinetic energy of the object can be described by 1 2 i 8 va Our example collision has a kinetic energy of 240 joules The foamlike material should be able to absorb 240 joules before bottoming out Energy absorbed by foam 5 IlwtgGdg 9 0 Length and width are assumed to be 30 and 40 cm respectively Thickness is assumed to be 1 cm as mentioned earlier The foam must be able to withstand a a of05 without bottoming out This means that it will be compressed to half its original thickness upon the example impact Solving for G gives a compression modulus of 1600 kPa or 232 psi The ideal material should be viscoelastic and have a G as close to 232psi as possible To minimize mass density must also be taken into account Our second performance index shows the goal of getting the compressive modulus as close to 232 psi as possible while still minimizing the weight 1 7lG7232lp M2


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