Engineering Design Communication Engineering Design Process

Chapter 11.1, 11.2.1,11.2.2, 11.3 Pictorial Projections

Chap 7.1-7.5,7.12-7.17

Design Design is the process of conceiving or inventing ideas and communicating those ideas to others in a form that is easily understood.

Design • • • •

Aesthetic Design Functional Design Product Design System Design

Design Phases •

Traditional Engineering Design – linear – iterative

Design • Concurrent Engineering Design • nonlinear

• Note in the concurrent model, problem identification becomes a part of the ideation phase

Problem Identification The first step in solving a problem is a clear statement of the problem. A needs statement can help coordinate the design effort and keep it moving in the right direction.

“Removing and disposing of large amounts of snow from parking areas is a major expense for the city of West Yellowstone. The current solution is to transport the snow several hundreds of miles to a facility where it can be dumped. A local facility is needed to allow the disposal of excess snow from streets, parking lots, and other areas. Research and design an energy-efficient and costeffective snow holding and disposal system.”

Problem Identification • Problem Statement • Research • Data gathering • Objectives • Limitations/Constraints • Scheduling

Design Constraints Limit the Range of Options • Functional (size limits loads, operating conditions…) • Ergonomic (useablility by humans) • Aesthetic • Economic • Legal • Time

Tastes in styling (aesthetic) have changed from the fins on the 1959 Cadillac to the streamlined appearance of the 1998 version

Ideation Where do you come up with your ideas?

Research • Literature (academic journals, conference proceedings, government reports, company reports, texts, manuals) • Patent searches

www.uspto.gov • WWW • Consumer surveys

Brainstorming • • • • •

No criticism Wild ideas welcome More is better Work off other ideas Have one person act as scribe & record ideas & help limit criticism

Pictorial Sketching • Represents a 3D object on a sheet of 2D paper by orienting the object so that you can see its width, height and depth in a single view

Pictorial Projections • Isometric − representation of an object by using drawing axes based on 30o, 150o, and 90o angles.

• Oblique − representation of an object by using drawing axes based on 30 or 45o and 90o angles

PICTORIAL • Perspective Sketching − shows object as it would appear in

photograph-portions further away appear smaller –Most realistic looking view

Axonometric • Trimetric −All three angles are unequal

• Dimetric −Two of the three angles are equal

• Isometric −All three angles are equal

Isometric Sketching • ISOMETRIC: shows the object rotated and tipped so that you are looking onto the corner where the major axes directions meet

Isometric

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The bottom edges are angled at 30 deg The angles between the axes appear as 120 deg

Isometric • Because top, front and sides are foreshortened(shown smaller than actual size) the same amount, you can make measurements along these axes • Lines parallel to the isometric axis lines are sketched to represent their actual lengths on the object (or proportionately smaller)

Isometric • Lines not in the same direction as the isometric axes (non-isometric lines) will appear other than their actual lengths • As a circle is tipped away from you it appears elliptical, circular shapes will appear elliptical in an isometric sketch

Isometric Sketching Sketch isometric axes 1. Orient part so that it shows object clearly 2.

3.

4.

If you know the length, width, height plot them on the isometric axes, sketch connecting isometric lines Locate non-isometric lines by measuring their endpoints along isometric lines Isometric grid paper may be useful

Sketching Isometric ellipses

• First locate center and sketch shape of box • Sketch the ellipse tangent to the walls

Oblique Sketches • Starts with front surface as looking straight onto it • Depth represented by parallel lines extending back from the front surface • When the depth is shown full scale the drawing is called a cavalier projection • When the depth is shown half size the drawing is called a cabinet projection

Oblique

• If back surface of object is same as front, a quick way to create an oblique sketch is to draw the front surface , then sketch it again (offset)

Oblique • Circular shapes in front view appear circular (as opposed to elliptical in isometric) • Most characteristic shapes usually shown in front • Showing depth full size contributes to distortion so obliques generally show depth less than full size

Obliques - Front, Axes, Parallels, Scale • Obliques - Front surface shown in “true shape”

• Oblique Axes

remain parallel Width • Depth Scale =

length of depth unit length of width (or height) unit

De pt 45 h

Height

• Parallel Lines

Oblique Types, Depth Scales, and 4 x 4 x 4 Cube in Oblique Representation Uses Type Cabinet

Cavalier General DEPTH = 2 SQUARES

Scale 0.5

Use items with little side detail

1.0 side detail - depth not great 0.5Æ1.0 easy to create w/ grid paper DEPTH = 4 SQUARES

DEPTH = 2 DIAGONALS

Scale = ?

CABINET

CAVALIER

GENERAL

Steps in Sketching Oblique Pictorials Edges parallel to axes

Best Shape Description Height and Width at 90 degrees

Depth at 45 degrees Decide oblique type

FRONT Parallel to axes

Locate along edges

Visible only

Inclined Surfaces in Oblique

Oblique Pictorial Characteristics

Oblique Pictorials are used when most of the details are on the front face (or a face parallel to front).

Perspective • Lines parallel on object are not shown parallel in the drawing • Receding parallel lines converge at a vanishing point • The horizon line in a perspective sketch is a horizontal line that represents the eye level of the observer

Perspective • To create illusion of depth, use guide lines called projectors, that run from the corners of the object to the vanishing point • Can have multiple vanishing points

Perspective • One point perspective

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Two point perspective

Sketching a perspective • Sketch the front surface true size on sheet • Add a horizon line and vanishing point • Draw projectors from front of object to vanishing point • Estimate depth of object and lightly sketch back surface • Connect corners, create edges/surfaces, darken

Perspective • Disadvantages −Time consuming −Size function of distance so difficult to tell whether objects are same size or simply farther away

• Advantages −Most realistic view

• Many architectural applications