MIL-HDBK-3F Volume 3,Chapter 4 Building Block Approach for Composite Structures 5.Laminate design should be fiber-dominated by definition,i.e.,a minimum of 10%of the plies should be in each of the0°，+45°，-45°，and90°directions.For tape and fabric laminates,always input the 0 or 1-axis strength allowable values in both the 1-and 2-axis slots in the analytical methods for tensile and compressive loads.Shear inputs will be as described above.This ap- proach will ensure fiber dominated failure and was first presented by Grimes in Reference 4.4.1.1.All laminates should be balanced and symmetric. NOT PART OF BBA 7777ZZZ22Q7 ALLOWABLES PartA ALLOW BLES COUPONS GENERATION BUILDING BLOCK KAPPROACH (BBA) ELEMENTS-SNGLE LOAD PATH B玉cTo2 TCAL SE OET ANO SUBCOMPONENTS-MULTPLE LOAD PATH COMPONENTS-CONTOURED,MULTIPLE LOAD PATH FULL-SCALE ARCRAFT STRUCTURE FIGURE 4.4.1.1 Aircraft structural development goals using building block approach(BBA). A structure classification/allowables chart which defines the relationship between aircraft structure criticality and the allowables requirements for prototypes is presented in Table 4.4.1.1(a).In Table 4.4.1.1(b)structural classification vs.physical defect maximum requirements are given so that the ac- ceptable physical defect size parameter varies indirectly with the aircraft structure criticality.Thus,aircraft structure criticality controls the reliability of the data(allowables)and the material and parts quality that are necessary to support it. 4-7MIL-HDBK-3F Volume 3, Chapter 4 Building Block Approach for Composite Structures 4-7 5. Laminate design should be fiber-dominated by definition, i.e., a minimum of 10% of the plies should be in each of the 0°, +45°, -45°, and 90° directions. For tape and fabric laminates, always input the 0° or 1-axis strength allowable values in both the 1- and 2-axis slots in the analytical methods for tensile and compressive loads. Shear inputs will be as described above. This ap￾proach will ensure fiber dominated failure and was first presented by Grimes in Reference 4.4.1.1. All laminates should be balanced and symmetric. FIGURE 4.4.1.1 Aircraft structural development goals using building block approach (BBA). A structure classification/allowables chart which defines the relationship between aircraft structure criticality and the allowables requirements for prototypes is presented in Table 4.4.1.1(a). In Table 4.4.1.1(b) structural classification vs. physical defect maximum requirements are given so that the ac￾ceptable physical defect size parameter varies indirectly with the aircraft structure criticality. Thus, aircraft structure criticality controls the reliability of the data (allowables) and the material and parts quality that are necessary to support it