Research on the Optimization of the Structure Design of Functional

Sofa Based on Modular Technology

Lu Lu

, Shaohui Su

, Shengran Meng

, Yiting Wang

, Chang Chen

and Guojin Chen

1,2,3,4,5,6

Department of mechanical electronics,Hangzhou Dianzi University,Xuelin Street,Hangzhou,China

Keywords: Functional sofa, Structural design optimization, Modularization technology.

Abstract: This paper is based on the sofa as a modular research object, and analyzed the current situation of the sofa

modularization. In view of the function sofa included in sofa, this paper puts forward the optimization

method of the structure modularization of the function sofa. Combined with concrete examples,

modularization technology is used to analyze the structure of existing functional sofas, and the methods of

modular classification and structural design optimization are proposed.

1 INTRODUCTION

Nowadays, the furniture market is developing

rapidly, there are countless brands and many

varieties, what is dazzling. The designer's

imaginative imagination makes the various furniture

shape different, that causes the consumer to choose

the furniture which he is interested in to be more

difficult. In particular, the large role of the living

room--sofa, which is a difficult problem that people

choose. How to quickly choose, design, produce

sofa product are customers, designers, production

personnel who are expected. So the modular design

of the sofa is put on the agenda.

Based on furniture function, habit, human body

mechanics and so on, the furniture is decomposed

rationally, the furniture is decomposed into standard

unit, and the function of these standard cells is

summarized and simplified, and merged into

modules. Different modules have their own

independent functions, with similar or similar

functions, merged into a common module; there are

some modules to meet the special functions of the

furniture, merged design for the dedicated module. If

a module is not satisfied the rule in the future, a new

modular design is proposed, which is added into the

module library.

In the current sofa module, the module may be a

combination relation. Module is the most basic unit

of furniture, multiple modules can be composed of

one or several new two-level modules, two-level

modules can and other two-level modules or even a

class of modules into a three-level module, and so

on. Until the composition of the customer needs of

the furniture combination. The furniture not only

changeable, but also diverse functions, at the same

time to meet customer requirements, to encounter

interchangeability, universality and other design

principles.

Analysing to the sofa structure, function,

characteristics ， we can draw the following four

kinds of modular sofa: ① suspension module, ②

load module, ③ splicing module, ④ hybrid module.

The existing modularity advantage is that they are

based on the basic form of “functional form” which

can stand in the angle of function, promote the

designer to produce new idea, and also conducive to

customer and designer choice. The disadvantage is

that it cannot be accurately divided into similar

modules, which according to the overall furniture

function of the division module. Instead of dividing

the module according to the structure and function

of the parts, so we need a new modular sofa design.

2 MODULAR

2.1 Basic Ideas

The structural design of functional sofas optimizes

its structure and parameters by means of

modularization, its main contents are:

1) Accurate division of modules. The module

needs the accurate division, guarantees its structure

function does not overlap.

2) The structure inside the module is optimized.

Existing product structure is various, it is need to

think that the similar structure how to optimize it.

3) Determination of key parameters. The

serialization standardization of parameters is the

most intuitive point to improve the efficiency.

3 FUNCTION SOFA

MODULARIZATION

3.1 Module Division

The most basic principle of module division is (1)

functional Independence principle, (2) structure

independence principle, (3) serialization,

standardization, generalization three principles.

Functional sofa module division is aimed at the

specific functions of furniture, the same or similar

units split, with modular design principles for

induction and unification. The process of division as

shown in Figure 1, after the survey of specific

structural data, performing functional analysis and

module division, if not satisfied with the module

results, then continue to these two steps until

determined the module.

Figure 1: Module partitioning process.

3.1.1 Function Analysis

Functional sofa structural design of the module

division is focused on design-oriented, analysis the

total function of the product, decomposed into a

series of basic functions. As shown in Figure 2,

according to different levels of division, can criteria

the total function is divided into the smallest

functional unit.

Figure 2: The function decomposition process of the

product.

More research are with function analysis as the

main factor, while considering other factors of the

modular design method.

3.1.2 Determination Module

Functional analysis gets a variety of functional

factors, some can be referred to as a separate

module, some need to be based on the basic features

of functional sofa modules and correlation analysis,

the combination of different functions into a new

module. The modules conform to the principle of

functional independence and structural

independence. The internal classification of modules

is taken the standard of the structure of small

differences for the classification, divided into

modules within the first class to the Nth class.

3.2 Structural Optimization

Optimal design is the best optimal design scheme

under the condition of satisfying the given

constraints. Functional sofa design options can be

optimized in any way, such as size, shape,

installation location, manufacturing costs, material

types, etc. The purpose of structural optimization

design is to realize the innovation of product

function and morphological structure on the basis of

saving material and simplifying technological

process.

3.2.1 Optimized Design of Structural

Strength

Function sofa optimized design of structural strength

is to study the connection between the parts of the

cross section size, so that its structure is the lightest

or most economical, often known as size

optimization, it is the lowest level of structural

optimization design, but also the most widely used.

Size optimization is to reduce the cost of materials

on the basis of ensuring the structural strength

requirements.

3.2.2 Optimized Design of Structural Forms

Functional sofa structure optimization design,

change the geometry of the structure, which is called

structural shape optimization. Then allow the

optimization of the structure layout and material

distribution, i.e. topology optimization of the

structure. The goal of topology optimization is to

find the best material allocation scheme. Through

the calculation of material cost and labor cost, found

out the optimal material distribution and distribution

scheme.

(1)

Formula (1), ‘Q’ for the total price, ‘ci’ for

material dosage, ‘mi’ for material price. According

to the different types of materials are divided into

‘i’=1, 2, 3, 4 ..., different materials correspond to

different prices, ‘t’ for product work, ‘d’ for labor

cost. The product total price ‘Q’ can be calculated

by formula (1).

3.3 Determination of Key Parameters

Parametric design is to achieve the entire product

parameter definition by changing the size of a part or

parts, or by modifying the parameters that have

already been defined. The key dimensions are

determined by various external constraints,

including human mechanics, packing size, etc. The

remaining parameters are solved by means of

numerical method and symbolic calculation, and the

remaining parameters are obtained by transforming

the constraints into a series of algebraic equations.

4 EXAMPLES

Take a backrest of company's functional sofa as an

example, make a set of modular analysis.

4.1 Function Sofa Module Split

According to the function analysis, the function sofa

each structural part is different, each component

realizes the function also to be different, will

decompose the product to the smallest structure

function. As shown in table 1, the last column is the

smallest function unit. Third column is the

secondary functional unit. Unit combination

become Modules into third columns.

Table 1: Functional sofa module division.

Function

Sofa

Backrest

— —

Handrails

Seat

frame

Footrest

Middle

backrest

Middle

turned

backrest

Middle seat

front boar

Tea table

backrest

Tea table

turned

backrest

Tea table

seat

—

Sofa bed

Backrest,

Handrails

Sofa bed

front boar

Angle

Angle back

—

Angle seat

4.2 Backrest Module Classification

4.2.1 Preliminary Classification

Take the backrest as an example, referring to all the

backrest types, all the back backs are as shown in

Figure 3a, 3b, 3c, 3d, 3e, 3f, plus all the strange

backrest, altogether seven categories.

Figure 3a: Backrest first class.

Figure 3b: Backrest second class.

Figure 3c: Backrest third class.

Figure 3d: Backrest fourth class.

Figure 3e: Backrest fifth class.

Figure 3f: Backrest sixth class.

This is based on the different structure of the

backrest, summed up seven kinds of preliminary

types. Because the principle of modularity is that the

smaller the number of modules the better, so the

structure of the backrest need to optimize the

module.

4.2.2 Structure Optimization

Figure 3 the top wood of all backrest (called

backrest top wood) has two kinds of specifications

20mm*40mm and 20mm*50mm. The use of testing

found that 20mm*40mm can meet the strength

requirements of the backrest top wood size

optimization.

Backrest sixth analogy class fifth internal

structure more than one wood side, the use of

detection found to meet the strength requirements,

you can delete the sixth class, backrest topology

optimization.

The first type of backrest and the second type of

backrest, the third type of backrest and the fourth

type of backrest of external structure similar to the

internal structure of some different, so the cost of

accounting to eliminate the high cost of the

structure. The comparison of figure 2, the first type

of backrest and the second type of the backrest are

shown difference as figure 4a; the third type of

backrest and the fourth type of the backrest are

shown difference as figure 4b.

Figure 4a: A comparison between the first class and the

second class.

Figure 4b: A comparison between the third class and the

fourth class.

According to table 2 cost table, using formula (1)

to calculate the cost of their different structure, the

results are shown in table 3.

Table 2: Cost table.

Labor costs

uan/min

)

0.3

12mm thick

oard (yuan/sqm) 20

40*20 wood square (yuan/m) 1.5

Average opening of laminated plate (sec) 20

Average wood o

ening (sec) 5

Table 3: Comparison of backrest cost.

Manu

work

(minu

tes)

Plate

dosag

e (sq.

Amou

nt of

wood

(m)

The

total

length

of the

materi

(secon

ds)

Total

Cost

(yuan)

①

3.2 0.16 0.04 50

4.220

②

3.7 0 0.91 25

2.475

③ 4.1 0.13 0.05 155 3.905

④

3.5 0 0.87 25

2.355

This shows that the backrest of the first category,

the backrest of the third type of open materials

longer and higher costs, so delete them, retain the

second type of backrest, backrest to the fourth

category. Optimized for backrest topology

optimization.

4.2.3 Final Classification of Backrest

Modules

Figure 5: Final classification of backrest module.

After the end of the backrest category deletion, the

final backrest module classification results are

shown in figure 5.

4.3 Size Division

4.3.1 Points of Attention for Size Division

From the perspective of module division, each

module has its own size series, the time of the

module division to pay attention to 3 points: 1, the

size division to notice the correlation between each

module, such as the width of the iron frame and the

width of the back and the width of the frame is

consistent, so as to match. 2, the size is from the

total data extracted from the summary, also need to

find different products to verify the size of the

design is consistent with the product. 3, the size of

the division also needs to be noted is to meet the

volume of the container.

4.3.2 Key Dimensions of Backrest

Figure 6: Key dimensions of backrest.

As shown in figure 6, the width ‘C’ between the two

planks is determined according to the size of the iron

frame. Because the iron frame is provided by the

Iron stand factory, they have the specific data size,

so the backrest width can be determined as a series.

4.3.3 Association of Dimensions

Figure 7 is the side view of the sofa, ‘a’ is the total

depth of the sofa, ‘b’ is the function of the sofa

without the angle of the total height, the size series

of the seat frame deep ‘d’ determined by the packing

size, the gagnier depth of the backrest is a fixed

value ‘m’, the angle between the backrest and the

seat frame ‘α’=106°, the angle between the ground

and the frame 2°, and ‘a’, ‘b’, and ‘m’ are known,

thus, the size series of the height ‘c’ of the backrest

can be calculated according to the formula (2) and

(3). And ‘e’ is the height of the seat, can be based on

the formula (4) to calculate the size of the seat high

‘e’ parameters.

Figure 7: Sofa side view.

(2)

=c+

(

)

(4)

5 CONCLUDING REMARKS

In this paper, on the basis of the current modular

sofa, a new version of the sofa module is

established, and this new type of sofa

modularization is applied to the company example.

Not only reform of the company's old style, but also

for the design of new styles brought convenience.

The next step is to sum up a set of sofa modular

method, perfect sofa modular theory, then establish

the relevant quotation system, it can be used by

designers, sales, customers, to form a customized

sofa and can offer independent pricing system.

ACKNOWLEDGEMENTS

Thank the National Natural Science Foundation of

China (Grant No. 51475129, 51675148, 51405117)

for its strong support for this paper.

REFERENCES

1. Peng Liang, Hu Jingchu, 2003. Home Design and

Craft, Higher Education Press. China, 8

edition.

2. Thomas, D., Miller, Per, Elgard, 1998. Defining

Modules Modularity and Modularization, Proceedings

of the 13`" IPS Research Seminar. USA.

3. Shao Shuguang, Tan Jianrong, 2004. Research on

Rapid Application of Standard System in Mass

Customization, Machine Tool & Hydraulics. China,

edition.

4. Xu Shuo, Tao Yubo, Li Peng, 2011. Application of

Modularization in Cabinet Furniture Design Towel,

Forestry Machinery and Woodworking Equipment.

China, 11

edition.

5. Wu Shijun, Sun Wei, 1994. Computer-aided modular

design, Machine Design. China, 4

edition.

6. Cheng Haojun, 2007. A Preliminary Study on the

Design of Sofa Based on Functional Modularity,

Furniture & Interior Design. China, 11

edition.

7. Sa' ed, M., Salhieh, Ali, K., Kamram, 1999. Macro

level product development using design for

modularity, Robotics and Computer Integrated

Manufacturing. USA.

8. Jia Yanlin, 1993. Modular design, Beijing:

Mechanical Industry Press. Beijing.

9. Jiang Hui, 1998. The theory and practice of Computer

Aided modular design of machine tools, Ph. D. thesis,

Tianjin University. Tianjin, 5

edition.

10. Lin Hai, Wu Jianfeng, 2004. On the Method of

Division of Furniture Modules, New Design Design.

China, 5

edition.

11. Zong Mingxi, Cai Ying, Liu Xudong, 2003. Multi-

angle and hierarchical module division method in

product modular design, Journal of Beijing Institute of

Technology. Beijing, 5

edition.

12. Gu, P., Sosale, S., 1999. Product modularization for

life cycle engineering, Robotics and Computer

Integrated Manufacturing. USA, 15

edition.

13. Ulrich, K., 1995. The role of product architecture in

the manufacturing firm, Research Policy. USA, 24

edition.

14. Stone, R., B., Wood, K., L., Crawford, R., H., 2000. A

heuristic method for identifying modules for product

architectures, Design Studies. USA, 21

edition.

15. Salhieh, S., M., Kamrani, A., K., 1999. Macro level

product development using design for modularity,

Robotics and Computer Integrated-Manufacturing.

USA, 15

edition.

16. Russell, L., Ikoff, 2009. Optimization Design: How to

Solve the Crisis of Enterprises in Tomorrow, Beijing:

China Renmin University Press. Beijing.

17. He Fengmei, 2008. Structural strength analysis and

optimization design of panel furniture based on

ANSYS, Harbin: Northeast Forestry University.

Harbin.

18. Wu Binfang, Xiong Hua, Zhang Jing, 2014. Optimum

Design of Supporting Slab Structure of Corrugating

Machine Based on Finite Element Analysis, Packaging

Engineering. China, 5

edition.

19. Li Fang, Ling Daosheng, 2002. A review of the

optimization design of engineering structures, Journal

of Engineering Design (Engineering and Development

of Machinery, Equipment and Instruments). China, 5

edition.

20. Zhang Feng, Li Zhaoqian, Huang Chuanzhen, 2002.

Research Development Status Quo of Parametric

Design, Mechanical Engineer. China, 1

edition.