The morphological box is—beside its use as a creativity method—a central element in design methodology. There the morphological box is one work step in the design process.
Hence it occurs quite often in Technical Reports.
Characteristic attributes of design methodology are thinking in functions and the sequence of work steps.
Starting from the list of requirements (requirements specification), the main function for the piece of equipment that is to be planned must be defined. It has proven to be practical to set up the list of requirements in the form of a table. Next the main function is divided into sub functions. The sub functions are always formulated according to the principle“execution on the object”. Examples: create force, transform torque, guarantee steerability etc. Then design solutions are developed for each sub function.
In the following step the sub functions and the found solutions for the sub functions are clearly arranged in a matrix-shape in the morphological box, i.e. in a special table. The solutions for the sub functions can be displayed in the table cells only verbally (very often!), only graphically (with principle drawings) or verbally and graphically. From here on two different options how to proceed are possible, i.e. with several concept variants or one concept variant.
Different concept variantsare usually marked in the morphological box with coloured or otherwise distinguishable lines. You can also use numbers or abbreviations. Please refer to Table3.1to see such a morphological box with several concept variants.
Then the concept variants are evaluated with respect to their technical and economical properties, Tables3.5and3.6. The results of this technical and economical evaluation will be summarized in the s-diagram, Fig.3.8. In the s-diagram you can recognize the best-suited concept variant.
In the evaluation procedure withone concept variant only a morphological box is arranged without marking concept variants. Then all design solutions of the sub functions are verbally evaluated. This means, that for all design solutions of the sub functions their advantages and disadvantages are listed in bullet lists. The design solution that shall be used is announced in the text in a separate line as follows“selected: <complete name of the solution of the sub function>”. Then follows a short explanatory statement of about one to three sentences. The concept variant is now mentally combined and mounted from the best-suited solutions of each sub function. The marking of this concept variant in the morphological box follows at the end of the verbal evaluation, e.g. by shading the selected solutions of the sub functions in bold, see Table 3.2.
If a verbal evaluation of a sub function solution has only advantages and disadvantages are not specified (or vice versa), then you should express that with the word“none”or with the symbol“–”. Now an example for such a verbal evaluation is shown for“Sub function C: lift water”.
Verbal evaluation of a sub function solution Solution C2: Rotary pump
Advantages: –smooth
–large delivery volume
Disadvantages: none (or“–”)
In the following you will get to know both variants of the morphological box (with several or only one concept variant) in a common example. Both variants of the mor- phological box refer to a fast turn-off device of a nuclear power plant, which has been developed at University for Applied Sciences Hannover for a design planning task.
In the first morphological box, Table3.1, several concept variants are marked. In a Technical Report the different concept variants should be marked—if possible—with a colored line for each concept variant, because the readers can then distinguish the concept variants best. Colored pencil is better suited than other pens, because the color does not appear on the rear side of the paper, as this is often the case, if you use highlighter or felt pen. Sometimes this even happens with ball pens. Here, digits in brackets are used to distinguish the concept variants. In any case you have to undoubtedly assign the different colors or line types and line thicknesses or numbers or abbreviations to the different concept variants in a legend below the morphological box.
In the morphological box with several concept variants you mark the solution, which is best-suited after the technical and economical evaluation, with a much thicker line, if printing and duplication is in black-and-white. If you use digits or abbreviations, you may use boldface typing to mark the chosen concept variant.
In the morphological box with only one concept variant you mark the solutions of the sub functions, which are best-suited after the verbal evaluation, with a bold emphasis, Table3.2.
Table 3.1 Morphological box (for a fast turn-off device in a nuclear power plant) with several concept variants, the electrical solution has been selected
Sub functions Solutions of the sub functions
1 2 3 4
A Notice incident Electromagn.
clutch (1) (3)
Sensors (2) B Disconnect device from
normal operation
Electromagn.
clutch (1) (2) (3)
Hydraulic clutch
Pneumatic clutch C Lower control rods Electric drive (3) Hydraulic
drive
Pneumatic drive (2)
Self- weight (1)
D Connect brakes Electromagn.
clutch (3)
Hydraulic clutch
Pneumatic clutch (2)
Always connected (1) E Create braking force Disc break (2) Drum break
(1)
Induction break (3)
Hydraulic damper F Transmit braking force Cogwheel and
cograil (1) (2)
Threadrod and nut
Friction wheels (3) G Control braking
operation
Centrifugal governor (1) (2)
Time controller
Distance controller (3) H Enable end cushioning Hydraulic oil
brakes
Hydraulic damper (1) (3)
Pneumatic damper (2) Legend
Variant 1 = electrical-mechanical solution Variant 2 = electrical-pneumatical solution Variant 3 = electrical solution
Table 3.2 Morphological box (for a fast turn-off device in a nuclear power plant) with one concept variant
Sub functions Solutions of the sub functions
1 2 3 4
A Notice incident Electromagn.
clutch
Sensors B Disconnect device
from normal operation
Electromagn.
clutch
Hydraulic clutch
Pneumatic clutch C Lower control rods Electric drive Hydraulic
drive
Pneumatic drive
Self-weight
D Connect brakes Electromagn.
clutch
Hydraulic clutch
Pneumatic clutch
Always connected
E Create braking force Disc break Drum
break
Induction break
Hydraulic damper F Transmit braking force Cogwheel
and cograil
Threadrod and nut
Friction wheels G Control braking
operation
Centrifugal governor
Time controller
Distance controller H Enable end cushioning Hydraulic oil
brakes
Hydraulic damper
Pneumatic damper
Special Design Rules for the Morphological Box
– The various sub functions in the morphological box usually have a different number of solutions of the sub functions. This results in empty cells at the right margin. These empty cells remain white, they are not shaded in gray or crossed out.
– Entries in the morphological box should always be left justified. If such entries are centered, this results in a too confusing layout.
– If you define several concept variants, you should give them meaningful and easy-to-remember names. Examples:
articulated arm, rotatable, and portal roboter or hydraulic, pneumatic, and electric solution.
– In the following parts of the Technical Report these variants are always referred to with their once defined names and even sketches of the concept variants are labelled with these names as well. This is much better than names like Variant 1, Variant 2, Variant 3 etc., because you can remember names much better than digits and combine the names with inner images of the concept variants in your head.
– You should identify your designed solutions of the sub functions horizontally with numbers and the sub functions vertically with capital letters. This has the following advantages: If you address cell 3.2, it is not clear, whether this is the second cell in the third row or the third cell in the second row. However, if you apply the recommen- dation above, C2 is the second solution of sub function C. This unique name can e.g.
be used in the verbal evaluation of the solutions of the sub functions.
– If a sub function has several subgroups or characteristics, you can subdivide this sub function in the morphological box. The subgroups are then“numbered” with small letters. For example, sub function C“store water”(in a water purification plant) shall be subdivided in container number, type, shape, and size. In the morphological box, this has to be noted as follows: The solutions of the sub functions are addressed with a combination of capital letter, small letter, and number, e.g. Cb2 canister, see Table3.3.
– If the solution of a sub function needs to be subdivided into several subgroups or characteristics, this is not marked with another number or letter, but the term which describes the solution of the sub function expands across several columns and every subgroup gets its own Arabic number. In the next morphological box, two solutions of
Table 3.3 Morphological box: sub function with several subgroups or characteristics Sub functions Solutions of the sub functions
1 2 3
C Store water
Ca Number Three Five Ten
Cb Type Barrel Canister Bottle
Cc Shape Cylinder with lid Cuboid with handle Cylinder with neck
Cd Size 600 l 100 l 50 l
sub functions are subdivided into subgroups: air cooling and water cooling of a motor.
The subgroups each have their own number, so that they can be addressed without doubt with letter and number (B1 ring cooler to B4flow cooler), see Table3.4.
After the design of the morphological box is described, in the next section you willfind information regarding evaluation tables.