MIL-HDBK-17-1F Volume 1,Chapter 1 Objectives 1.3.1 Strength properties and allowables data Statistically-based strength property data are defined for each composite material system over a range of potential usage conditions.The intent is to provide data at the upper and lower limits of the po- tential environmental conditions for a particular material,so that application issues do not govern the me- chanical property characterizations.If data are also available at intermediate environmental conditions, they are used to more exactly define the relationship between the mechanical properties and the effect of the environment on those properties. The statistically-based strength data that are available are tabulated in Volume 2.These data are useful as a starting point for establishing structural design allowables when stress and strength analysis capabilities permit lamina level margin of safety checks.Where such cases exist,the MIL-HDBK-17 sta- tistically reduced strength data may be used in determining material design allowables.Depending on the application,some structural design allowables will have to be determined empirically by laminate,ele- ment,or higher level of testing,since MIL-HDBK-17 does not provide these data. Additional information and properties are added as they become available and are demonstrated to meet the guideline criteria.Typical property values,as well as S-values(see definitions)are included if they meet the approval of the MIL-HDBK-17 Coordination Group. When the guidelines or data requirements of MIL-HDBK-17 cannot be followed,the certifying or pro- curing government agency should be contacted to determine data requirements and other documentation which may be necessary to justify data values proposed or used by the manufacturer. 1.3.2 Volume 1:Guidelines for Characterization of Structural Materials This volume contains guidelines for determining the properties of composite material systems,their constituents,and generic structural elements,including test planning,test matrices,sampling,condition- ing.test procedure selection,data reporting,data reduction,statistical analysis,and other related topics Special attention is given to the statistical treatment and analysis of data.Volume 1 contains guidelines for general development of material characterization data as well as specific requirements for publication of material data in MIL-HDBK-17. It must be emphasized that this handbook differentiates between material basis values (material al- lowables)and design allowable values.Material basis values,being an intrinsic property of a composite material system,are the focus of this handbook.Design allowable values,while often rooted in material basis values,are application dependent,and consider and include specific additional considerations that may further affect the strength or stiffness of the structure.Also,when establishing application design values there may be additional certification or procurement agency requirements that go beyond MIL-HDBK-17. 1.3.3 Volume 2:Material Properties Volume 2 contains statistically-based data meeting specific MIL-HDBK-17 population sampling and data documentation requirements,covering constituents and material systems of general interest.Data published in Volume 2 are under the jurisdiction of the Data Review Working Group and are approved by the overall Coordination Group(The MIL-HDBK-17 Coordination Group and Working Groups are dis- cussed in Section 1.5).New material systems will be included and additional material data for existing systems will be added as data becomes available and are approved.Selected historical data from the MIL-HDBK-17A version of the handbook that do not meet current data sampling,test methodology,or documentation requirements,but that still are of potential interest to the industry,are also documented in an appendix to this volume. The material properties in Volume 2 are defined over a range of potential use conditions,focusing when possible,on the upper and lower material environmental limits so that application-specific environ- 1-3MIL-HDBK-17-1F Volume 1, Chapter 1 Objectives 1-3 1.3.1 Strength properties and allowables data Statistically-based strength property data are defined for each composite material system over a range of potential usage conditions. The intent is to provide data at the upper and lower limits of the po￾tential environmental conditions for a particular material, so that application issues do not govern the me￾chanical property characterizations. If data are also available at intermediate environmental conditions, they are used to more exactly define the relationship between the mechanical properties and the effect of the environment on those properties. The statistically-based strength data that are available are tabulated in Volume 2. These data are useful as a starting point for establishing structural design allowables when stress and strength analysis capabilities permit lamina level margin of safety checks. Where such cases exist, the MIL-HDBK-17 sta￾tistically reduced strength data may be used in determining material design allowables. Depending on the application, some structural design allowables will have to be determined empirically by laminate, ele￾ment, or higher level of testing, since MIL-HDBK-17 does not provide these data. Additional information and properties are added as they become available and are demonstrated to meet the guideline criteria. Typical property values, as well as S-values (see definitions) are included if they meet the approval of the MIL-HDBK-17 Coordination Group. When the guidelines or data requirements of MIL-HDBK-17 cannot be followed, the certifying or pro￾curing government agency should be contacted to determine data requirements and other documentation which may be necessary to justify data values proposed or used by the manufacturer. 1.3.2 Volume 1: Guidelines for Characterization of Structural Materials This volume contains guidelines for determining the properties of composite material systems, their constituents, and generic structural elements, including test planning, test matrices, sampling, condition￾ing, test procedure selection, data reporting, data reduction, statistical analysis, and other related topics. Special attention is given to the statistical treatment and analysis of data. Volume 1 contains guidelines for general development of material characterization data as well as specific requirements for publication of material data in MIL-HDBK-17. It must be emphasized that this handbook differentiates between material basis values (material al￾lowables) and design allowable values. Material basis values, being an intrinsic property of a composite material system, are the focus of this handbook. Design allowable values, while often rooted in material basis values, are application dependent, and consider and include specific additional considerations that may further affect the strength or stiffness of the structure. Also, when establishing application design values there may be additional certification or procurement agency requirements that go beyond MIL-HDBK-17. 1.3.3 Volume 2: Material Properties Volume 2 contains statistically-based data meeting specific MIL-HDBK-17 population sampling and data documentation requirements, covering constituents and material systems of general interest. Data published in Volume 2 are under the jurisdiction of the Data Review Working Group and are approved by the overall Coordination Group (The MIL-HDBK-17 Coordination Group and Working Groups are dis￾cussed in Section 1.5). New material systems will be included and additional material data for existing systems will be added as data becomes available and are approved. Selected historical data from the MIL-HDBK-17A version of the handbook that do not meet current data sampling, test methodology, or documentation requirements, but that still are of potential interest to the industry, are also documented in an appendix to this volume. The material properties in Volume 2 are defined over a range of potential use conditions, focusing, when possible, on the upper and lower material environmental limits so that application-specific environ-