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consists of relationships among the following three entities: (a) the PFM, (b) the geometric nature of the component surfaces, and (c) the contact conditions that exist on the interacting surfaces of the components in the assembly. The relationships among these three entities have been encoded in the form of rules making them more amenable to the implementation of the knowledge base in a computer-based IPD system. In Table 1.8, two rules from the component function-functional tolerance limit knowledge base are shown. In Rule 1, the interacting faces of two mating components, which have a PFM model � [0,1,1,1,0,0,{Contact Pressure (Numerical value)}], would have an interference fit condition whenever the two interacting faces have surface contact between them. In this rule, the contact pressure term would be derived from the behavioral attribute that would be assigned to the PFM model of the face. Next, the necessary amount of interference ( ) would be estimated using one of the equations provided in Rule 1. It should be noted that the interference between the two mating faces is directly influenced by the contact pressure (pc) associated between the two faces as well as other geometric and design parameters. The appropriate size tolerance limits are determined based on the face dimensions and the required interference at the contact in conjunction with the ISO standard fit tables. 23 � Similarly, two cylindrical surfaces, which maintain a surface contact between them and with PFM model � [0,1,1,1,0,0,{Contact Pressure (numeric term)}], would be assigned cylindricity form tolerance (Rule 2). It should be noted that the rules provided in the knowledge base can be applied to components that are subjected to a wide variety of component functions. This enhances the application and utility of the knowledge base in the synthesis of tolerance specifications. 2. Geometric entity-process error relationship knowledge base: The functional tolerance limits as established from the component function-functional tolerance limit knowledge base are further constrained with respect to various manufacturing, assembly, and inspection criteria associated with the different geometric entities of the components. The knowledge of the relationship between © 2001 by CRC Press LLC TABLE 1.8 Examples of Rules in the Component Function-Functional Tolerance Limit Knowledge Base Rule 1: IF interacting faces of two components have PFM model � [0,1,1,1,0,0, {Contact pressure = p c}] AND have surface contact THEN the two components have interference fit condition between them at the interacting faces - Interference ⇒ � �d i�p c 42.2 d � ------------------------------------ ⎛ o � 0.3di ⎞ ⎜---------------------------- ⎟ ⎝ � 6.33di⎠ Alternative expression ⇒ � ⎛pcdc -------- ⎞ ⎝ E ⎠ i where Young’s modulus of material of the two mating parts is given by Ei and Eo. do, di, and dc are the external, inner, and contact surface diameters, respectively; represent the Poisson ratio of the material of the two mating parts; denotes the change in diameter of the inner contacting surface due to the contact pressure, pc; denotes the change in diameter of the outer surface due to the contact pressure, pc; represents the total change in both internal and external diameters of the contacting surfaces. Application: The interference fit conditions between interacting faces are modeled as a contact between two cylinders. Depending on the interference and the dimensions of the surfaces, appropriate design tolerance limits (upper and lower size tolerance limits) are determined from the ANSI/ISO standard fit tables. In the case of planar faces, an equivalent cylindrical face is first established (using plane diagrams), and the corresponding tolerance limits are determined. Rule 2: IF the interacting face of a component has PFM model � [0,1,0,1,1,0, {Contact pressure � pc}] AND maintains surface contact with mating face AND the surface type is cylindrical surface THEN cylindricity form tolerance should be assigned on the face d 2 2 ⎛ c � di ⎞ ⎜----------------- � � 2 2 i⎟ ⎛pcdc -------- ⎞ ⎝dc�di⎠ ⎝ E ⎠ o d 2 2 ⎛ c � di ⎞ � � ⎜----------------- � � 2 2 o⎟ ⎝d c � di ⎠ �o,� i �i �o � d o
component geometric entities and various process errors that affect the accuracy of these geometric artifacts is stored in this knowledge base. The knowledge of the above relationships is stored in the form of rules that are applicable under the same specified conditions. For instance, a machined surface would be subjected to form errors arising from the deflection of cutting tools, vibration of tool posts, and cutting-tool wear. The knowledge of the above three parameters would be useful for determining the achievable form tolerances of surfaces manufactured using a variety of machining processes. 3. Process-tolerance limit data base: This data base provides information regarding the capabilities of the different manufacturing and assembly processes with respect to achieving certain size, form, and positional tolerances. This data base provides a general guideline of the range of process capabilities. A sample instance as shown in Table 1.9 depicts the process capabilities of different machining processes with regard to straightness tolerance. Schema for Tolerance Synthesis within the TSS System Given the knowledge regarding component functions, manufacturing processing information, and assembly plans, the global objective of a tolerance synthesis schema is to assign a set of size, form, and position tolerances along with datum reference planes to a component. This issue is further complicated by the fact that there exists an interdependency relationship between tolerances and the various inputs required for assigning tolerances. 27 This deadlock in assigning tolerances can be broken with a schema in which neither the tolerances nor the different tolerance inputs are affected by the breakdown in their interdependency relationships. In this section, we outline a tolerance synthesis schema that takes into consideration the above interdependency relationships and assigns tolerances on the basis of knowledge pertaining to component functions, manufacturing process considerations, and assembly process capabilities. With reference to Figure 1.13, the tolerance synthesis schema works in four distinct phases. • Phase #1 (Specification): In this phase, the tolerance synthesis schema requires the following inputs: Geometry description: The synthesis schema requires the organization of the part geometry along three hierarchical levels of representation (assembly, part, and feature level). The user is required to specify the part geometry description at the assembly level (i.e., spatial location of part in assembly), part level (i.e., spatial location of features in the part and their inter-relationships), and feature level (i.e., feature geometry). Part function specification: The user specifies the part behavior on the basis of a function vocabulary and describes the behavioral attributes associated with that function. Material and surface finish specification: The synthesis schema also requires that the user specify the material and surface finish characteristics of the part. © 2001 by CRC Press LLC TABLE 1.9 Process Capabilities for Straightness Tolerance for Different Manufacturing Operations Machining Process Straightness Tolerance Zone (mm) Drilling 0.001 Slotting 0.0005 Turning 0.0001 Boring 0.0001 Cylindrical grinding 0.00005 Reaming 0.00006 Surface grinding 0.00003 End milling 0.002 Note: The above data is available in References 23–25.
Page 1 and 2: COMPUTER-AIDED DESIGN, ENGINEERING,
Page 3 and 4: Library of Congress Cataloging-in-P
Page 5 and 6: Editor Cornelius T. Leondes, B.S.,
Page 7 and 8: Chapter 1 Chapter 2 Chapter 3 Chapt
Page 9 and 10: the implementation of the IPD syste
Page 11 and 12: In our IPD system implementations,
Page 13 and 14: 2. Specification of analysis-specif
Page 15 and 16: FIGURE 1.2 base or the design insta
Page 17 and 18: FIGURE 1.4 System architecture of t
Page 19 and 20: of a beam is considered for FEA. Th
Page 21 and 22: FIGURE 1.7 through the control expe
Page 23 and 24: 2. machining facility (e.g., gang m
Page 25 and 26: from the FBDS. The user also specif
Page 27 and 28: Depending on the type of feature to
Page 29 and 30: TABLE 1.6 Tolerance synthesis is de
Page 31: FIGURE 1.12 Display of the NC tool
Page 35 and 36: FIGURE 1.14 The system architecture
Page 37 and 38: TABLE 1.10 User Input for the Toler
Page 39 and 40: TABLE 1.11 Tolerance Specifications
Page 41 and 42: 7. Z. Young and I. R. Groose. A rul
Page 43 and 44: FIGURE 2.1 Tool paths generated for
Page 45 and 46: FIGURE 2.2 sented by instances of f
Page 47 and 48: TABLE 2.1 A CAD-Generated Hole Conf
Page 49 and 50: FIGURE 2.6 mounted on the rotary ta
Page 51 and 52: FIGURE 2.8 fixture for the machinin
Page 53 and 54: FIGURE 2.10 or best-fit, or the cur
Page 55 and 56: FIGURE 2.11 Linear approximation of
Page 57 and 58: FIGURE 2.13 Circular approximation
Page 59 and 60: FIGURE 2.14(b) Circular approximati
Page 61 and 62: FIGURE 2.16 Types of biarcs. FIGURE
Page 63 and 64: FIGURE 2.18 Approximation of scanne
Page 65 and 66: FIGURE 2.20 A touch trigger probe c
Page 67 and 68: TABLE 2.4 Substitute Elements in CM
Page 69 and 70: FIGURE 2.21 CMM planning requiremen
Page 71 and 72: Product Model Representation for Co
Page 73 and 74: © 2001 by CRC Press LLC TABLE 2.5
Page 75 and 76: TABLE 2.7 Partial Listing of Dimens
Page 77 and 78: 24. Makinouchi, S., Okamoto, M., an
Page 79 and 80: Bijan Shirinzadeh Monash University
Page 81 and 82: FIGURE 3.1 Trends in flexible manuf
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FIGURE 3.3 and constrain different
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Other Fixturing Techniques There ar
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FIGURE 3.6 contact point. The geome
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FIGURE 3.8 The vertical support fix
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and moments about the contact point
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een identified, the normals are use
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one of choosing the variables: such
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Fixture Module Location An importan
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FIGURE 3.15 Illustration of functio
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FIGURE 3.18 Minimum separation test
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direction) the face, respectively.
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FIGURE 3.21 Software structure for
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3.8 Conclusion A reconfigurable fix
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Heui Jae Pahk Seoul National Univer
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FIGURE 4.1(b) Conceptual framework
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4.3 Measurement Points Sampling and
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Surface S2 Measurement Path FIGURE
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FIGURE 4.4 Rough phase alignment ba
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deviation between the nominal CAD d
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FIGURE 4.6(a) Sum of squares distan
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FIGURE 4.7(c) Trailing edge. (c) th
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FIGURE 4.8(a) Profile tolerance of
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The calculated minimum form error i
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FIGURE 4.11(a) A typical mold havin
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FIGURE 4.11(d) Inspection results f
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FIGURE 4.12(c) Maximum deviation (p
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5.1 Introduction Developments in th
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process plan for a part (Figure 5.3
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FIGURE 5.5 leading to the developme
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the previously stored process plan
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FIGURE 5.7 Techniques of defining a
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Feature Recognition and Extraction
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in relation to another feature (e.g
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FIGURE 5.9 Framework for building a
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FIGURE 5.10 Process plan content.
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FIGURE 5.12 Schematic sketch of the
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Several techniques of defining a fe
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TABLE 5.1 Data Structure for Repres
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FIGURE 5.16 Classification of the t
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system to ensure that the part bein
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FIGURE 5.19 Graphical model of the
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TABLE 5.4 Data Structure for Repres
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FIGURE 5.20 Mapping between machini
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algorithms. (Some details of the pr
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FIGURE 5.24 An example rotational p
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FIGURE 5.26 Down_face-turn-up_face
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FIGURE 5.27 Procedure for machine t
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FIGURE 5.28 Determining the number
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DL is needed to be set only if the
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FIGURE 5.31 Operation sequencing co
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Cutting Tool Selection Selection of
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1. A tool is searched for in the da
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FIGURE 5.32 Inputs to optimization
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When these values are substituted,
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Usually, maximum and minimum speed
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FIGURE 5.33 Solution methodology.
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TABLE 5.6 Process Plan Internal Rep
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In a strict theoretical perspective
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18. Domazet, D. S. and Lu, S. C. Y,
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63. Prasad, A. V. S. R. K., Rao, P.
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CAD systems. The sample consists of
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learn to master the new system. An
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Although researchers appear to agre
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Link and Zmud28 found that organic
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Informal Training Informal CAD trai
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informal training programs, felt th
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6. C. A. Beatty, Tall Tales and Rea
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A.Y.C. Nee National University of S
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FIGURE 7.1 Planning, design, and ma
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A metal stamping can have the follo
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FIGURE 7.3 Strips used to notch out
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A Skeletal Approach for the Recogni
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These findings can be used to devel
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Semi-Direct Piloting In cases where
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a larger value, the die operations
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FIGURE 7.9 Symbolic relationship be
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FIGURE 7.11 The shape of the envelo
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TABLE 7.1 Schema for the Generation
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strong reasons to support a move to
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FIGURE 7.16 3-D CAD model of a part
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References Cheok, B.T. et al. (1994
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include the once forbidden generati
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A temporal matrix (T-Matrix) is pro
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FIGURE 8.1 A basic process. (From R
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FIGURE 8.4(a) Generate a new IG usi
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Note if the pair of nodes are both
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TABLE 8.1 Summary of the Rules Cond
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The correctness of these rules is e
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needs to show that after each full
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ule is violated, a warning should b
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Π1 Π3 Π4 FIGURE 8.8(a) After add
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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
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A ik � ‘U’ and is in a cycle
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FIGURE 8.12(a) Add [p2 t7 p7 t8 p4]
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FIGURE 8.12(c) Add a token to p8 vi
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FIGURE 8.12(e) Add [p8 t9 p14 t10 p
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FIGURE 8.13 An example of rule TT.0
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FIGURE 8.14 A GPN model of a machin
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FIGURE 8.15(b) The first exclusive
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FIGURE 8.15(d) The last exclusive T
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FIGURE 8.15(f) After entering the a
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FIGURE 8.15(h) Completion of Compon
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FIGURE 8.15(j) Two PP-generations:
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FIGURE 8.15(l) The last exclusive T
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t1 t5 p1 p5 t6 (a) t2 t3 t4 2 2 p2
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FIGURE 8.17 An example of partial f
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Theorem 10: If pi → pk in a synth
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Note that control transitions are o
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t j than the lower at , it indicate
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• Programming logic and VLSI arra
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7. Chao, D. Y. and D. T. Wang, Appl
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53. Villaroel, J. L., J. Martinez,
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q u : the numerator of the least ra
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geometric modeling, engineering ana
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In dimension driven or parametric d
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FIGURE 9.3 configuration of bodies
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FIGURE 9.6 FIGURE 9.7 Geometric Int
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FIGURE 9.8 Intersection of degrees
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will introduce a way to propagate p
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Completeness of Dimensions Complete
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FIGURE 9.12 3-D constraints. © 200
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The distance constraint from pt �
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therefore: Now merge the lists and
Page 329 and 330:
Quantity analysis methods have the
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y a revolute joint. By selecting al
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