Microstructure-failure mode correlations in braided composites

Explication of the fracture processes of braided composites is needed for modeling their behavior. Described is a systematic exploration of the relationship between microstructure, loading mode, and micro-failure mechanisms in carbon/epoxy braided composites. The study involved compression and fracture toughness tests and optical and scanning electron fractography, including dynamic in-situ testing. Principal failure mechanisms of low sliding, buckling, and unstable crack growth are correlated to microstructural parameters and loading modes; these are used for defining those microstructural conditions which are strength limiting

Yarn carrier apparatus for braiding machines and the like

A yarn carrier apparatus particularly suited for use in braiding machinery or the like due to its capability of continuous yarn feeding and retraction of long lengths of yarn. The yarn carrier apparatus comprises a yarn supply spool which is rotatably mounted within the housing, a spring motor also mounted within the housing and operatively connected to the yarn supply spool through a mechanical transmission assembly which is adapted to multiply rotational movement between the first element of the gear assembly operatively connected to the spring motor and the final element of the gear assembly operatively connected to the yarn supply spool. The spring motor is adapted to tension the yarn during both feeding and retraction thereof, and it is further adapted to periodically rotatably slip within the housing and partially unwind so as to allow for continuous withdrawal of a long length of yarn without the spring motor becoming fully wound and preventing further yarn retraction

On the mechanics of twist insertion.

Massachusetts Institute of Technology. Dept. of Mechanical Engineering. Thesis. 1965. Sc.D.Bibliography: leaves 192-195.Sc.D

Yarn carrier with clutch

A yarn carrier apparatus particularly suited for use in braiding machinery or the like due to its capability of continuous yarn feeding and retraction of long lengths of yarn. The yarn carrier apparatus comprises a yarn supply spool which is rotatably mounted within the housing, a spring motor also mounted within the housing and operatively connected to the yarn supply spool through a mechanical transmission assembly which is adapted to multiply rotational movement between the first element of the gear assembly operatively connected to the spring motor and the final element of the gear assembly operatively connected to the yarn supply spool. The spring motor is adapted to tension the yarn during both feeding and retraction thereof, and it is further adapted to periodically rotatably slip within the housing and partially unwind so as to allow for continuous withdrawal of a long length of yarn without the spring motor becoming fully wound and preventing further yarn retraction

On the dynamics of wool spinning

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1961.Includes bibliographical references (leaf 153).by Aly H. M. El-Shiekh.M.S

Mechanics of high speed texturing. Part III: Experimental studies of belt and ring twisting

This paper presents experimental studies of belt and ring twisting mechanisms. The effects of twister parameters such as the yarn crossing angle, the speed ratio, and the externally applied pressure are investigated, and the results support the theoretical analyses presented in the previous parts of this series. The preferred operating ranges of these twisters are also suggested

Mechanics of high speed texturing. Part II. Theoretical analysis of ring twisting

The mechanics of ring twisting are analyzed, and the effects of machine operating parameters such as the R/Y ratio (the ratio of the linear speed of ring to the speed of the yarn path), the ring crossing angle, and the externally applied pressure are discussed. The advantages of the ring twister are compared with the stacked disc spindle and the belt twister. The restraints in designing the ring aggregate are discussed in terms of the differential relative torsional slippage

STRETCH MERCERIZATION OF COTTON FIBERS. PART I. FIBER AND YARN PROPERTIES.

Three techniques were developed by which cotton fibers in roving from were mercerized and stretched to their original length and then neutralized in the stretched configuration. The effectiveness of the three stretching systems was evaluated by testing the processed fibers and yarns. The mechanical properties of the yarns made from stretch mercerized roving were compared with those of yarns made of untreated fibers and slack mercerized fibers. Their properties were also compared with the properties of yarns that were packaged mercerized and single strand stretch mercerized. The results show that a series of closely set rollers, gradually increasing in diameter from back to front, provide a reasonable device for stretching the individual fibers during mercerization. The yarn produced from rovings with this technique shows superior properties over those of other methods studied in this investigation. Yarns made of stretch mercerized roving will have higher strength retention after durable press treatment

STRETCH MERCERIZATION OF COTTON FIBERS. PART II: FABRIC PROPERTIES.

Slack mercerization followed by gradual restretching to the ratio of 1. 25 by a series of closely set rollers in Part I of this study was proven to be effective in stretching the individual fibers shrunken during mercerization. The effect of stretch mercerization in roving form using this technique on the mechanical properties of fibers, yarns and fabrics was investigated. Stretch mercerized roving was converted into fabric and its properties were compared with the properties of three similar samples: fabric from mercerized yarns, mercerized fabric, and unmercerized fabric. Fabrics woven from stretch mercerized roving possessed greater strength than the commercially yarn-mercerized fabrics. The fabric produced from yarns made from stretch-mercerized roving had the lowest values of percent reduction in grab strength and tearing strength after resin treatments with dimethylol dihydroxyethyleneurea