Fabrics subjected to rubbing tend to generate fuzz. Fuzz produces pills and spoils the appearance and quality of garments made of such fabrics. Using the geometrical structure of yarns and fabrics as a guide, this article deduces theoretically how fibers struggle not to slip out of the fabrics into which they are made. This struggle is referred to here in as “resistance to slippage.” Measuring the degree of this resistance has been experimentally proved useful for measuring the fuzz-generating tendency of fabrics.

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Here is an all-purpose electronic tensile tester experimentally produced. It can impose loads or extensions linearly or nonlinearly on test pieces by its automatic control mechanism. The mechanism has an analog computer which serves as a program generator. The characteristics of the tester, when used for tensile tests, and the results of the tests are:
(1) This tester is made up of three parts; i) a program generator which converts an arbitrary load or extension into an input voltage; ii) a controller of input loads; and iii) an output detector-recorder.
(2) The overall transfer function of the tester under load input is: G_of; (s)=K_A; G_p; (S)/S(T_M; S-1) e-^LS where G_p; (s) is the transfer function of a test piece. If a spring is placed where a test piece would be placed, the frequency response of the open loop is stable at ω 45rad/sec or less, even if the gain is 45dB.
(3) The overall transfer function of the tester under extension input is as shown below, the closed-loop frequency characteristic closely resembling that in a case where a spring is interposed under load input: G_ox; (s) K_B; /S(T_M; S-1) e-^LS
(4) The closed-loop transfer function under load input is: G_f; (s)=K_C; /T_M; S²-|1-K_A; LG_p; (S)|S-K_A; G_p; (S) e^-LS If a spring is placed where a test piece would be placed, the closed-loop fre uency is stable at ω 30rad/sec or less, even if the gain is 32.5dB.
(5) The closed-loop transfer function under deformation input is shown by this equation G_x; (s)=K_H; G_p; (s)/T_M; S²{1-K_B; L)S}K_B; e^-Ls With a spring used as a test piece, the closed loop frequency resembles that in a case where a spring is used as a test piece under load input.
(6) This tester has been experimentally proved capable of testing repeated tensile testing hitherto difficult. It is also capable of tests under loads or deformation input in various functions, e.g., tests under constant-speed load input.
(7) The mechanical transient characteristic of gum and fibers, ascertained from the results of tests under loads and deformation input, has the same tendency as a theoretical curve. This attests to the fidelity of the tester.
(8) Tests by our tester of the frequency response of fibers under loads and deformation input have shown that the phase leads if deformation input is used. By “phase leads” we mean “phase shifts to positive.”.
(9) The load output of the transfer function of Voigt-Maxwell's four-element model always shows in the function of sinhx(t), if the input is of deformation type.
(10) Some applied examples of tests possible by this machine will be given. We believe from the evidence that this tester is eminently suited for testing the dynamic mechanical properties of general industrial materials.

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