Abstract: Provided herein is a portable apparatus for surface inspection and electrolytic polishing, the apparatus including a housing where a motor and controller are embedded. The apparatus also includes a screw axis rotatable by the motor and a cylinder with a ball nut coupled to the screw axis and coupled to a slider. A plurality of guide members are included that each have an upper end coupled to the housing and a lower end coupled to a base plate. The guide member penetrates the slider, and the slider moves up and down along the guide members with the cylinder. A surface inspector and an electrolytic polisher are coupled to the slider and move up and down together with the slider allowing the surface inspector and the electrolytic polisher to test a test subject in various industrial fields, such as machinery, construction, chemicals, and the like.

Abstract: Method for evaluating an asymmetric residual stress for a material by the indentation test comprises applying the residual stresses with an uniaxial and an symmetrical biaxial tensions on the material and then performing an instrumented indentation test indenting an asymmetric indenter on the material; and comparing a slope of indentation load-depth curve when the long diagonal direction of the asymmetric indenter is perpendicular to the direction of the largest residual stress with that in stress-free state, and then a slope of indentation load-depth curve when the long diagonal direction of the asymmetric indenter is parallel to the direction of the largest residual stress with that in stress-free state, so as to evaluate the asymmetric residual stress for the material.

Abstract: The present invention relates to a method of evaluating the fracture toughness of a material using the continuous indentation technique. In the method of this invention, the stress coefficient, strain hardening modulus and yield stress of the material are determined using the continuous indentation technique and, thereafter, the reduced elastic modulus (Er) of the material is calculated. The effective elastic modulus and the initial elastic modulus are calculated and, thereafter, the damage parameter is calculated using the void volume fraction. The critical elastic modulus and the characteristic fracture initiation point of the indentation depth are determined using the damage parameter and, thereafter, the fracture toughness of the material is evaluated. The present invention is advantageous in that the fracture toughness of a brittle material can be evaluated precisely using a nondestructive evaluation technique.

Abstract: The present invention relates to a method of measuring residual stress and, more particularly, to a residual stress measuring method using a continuous indentation tester. Due to pile-up and sink-in of a material or a blunted tip, a conventional residual stress measuring method cannot compensate for error of a real contact (indentation) depth or directly remove stress through a thermal or mechanical technique in the conventional method of measuring residual stress of a weldment, so that it is very difficult to estimate a stress-free reference curve or to quantitatively measure residual stress. However, the present invention can precisely estimate a stress-free curve of a weldment using an indentation strength ratio (OIT ratio) of a stress-free base metal to the weldment, and compensates for error, occurring in the measurement of a material having a weldment or an anisotropic stress structure, based on the indentation strength ratio, thereby more precisely measuring residual stress.

Abstract: The present invention relates to a method of measuring residual stress and, more particularly, to a residual stress measuring method using a continuous indentation tester. Due to pile-up and sink-in of a material or a blunted tip, a conventional residual stress measuring method cannot compensate for error of a real contact (indentation) depth or directly remove stress through a thermal or mechanical technique in the conventional method of measuring residual stress of a weldment, so that it is very difficult to estimate a stress-free reference curve or to quantitatively measure residual stress. However, the present invention can precisely estimate a stress-free curve of a weldment using an indentation strength ratio (OIT ratio) of a stress-free base metal to the weldment, and compensates for error, occurring in the measurement of a material having a weldment or an anisotropic stress structure, based on the indentation strength ratio, thereby more precisely measuring residual stress.

Abstract: The present invention relates to a method of evaluating the fracture toughness of a material using the continuous indentation technique. In the method of this invention, the stress coefficient, strain hardening modulus and yield stress of the material are determined using the continuous indentation technique and, thereafter, the reduced elastic modulus (Er) of the material is calculated. The effective elastic modulus and the initial elastic modulus are calculated and, thereafter, the damage parameter is calculated using the void volume fraction. The critical elastic modulus and the characteristic fracture initiation point of the indentation depth are determined using the damage parameter and, thereafter, the fracture toughness of the material is evaluated. The present invention is advantageous in that the fracture toughness of a brittle material can be evaluated precisely using a nondestructive evaluation technique.

Abstract: Disclosed herein is an apparatus for measuring residual stress, methods of measuring residual stress data and residual stress using the apparatus, and a recording medium for storing software of the residual stress measuring method. The present invention is advantageous for evaluation of a mechanical material property and is non-destructive. Further, the present invention is widely applied to fields ranging from a microscopic area, such as a thin film or micro device, to a large-sized structure, and is not influenced by a microstructure by controlling the range of an applied load. Further, the measuring apparatus of the present invention is minimized in its volume to be easily attached to an actual structure. Further, in the present invention, various attaching devices are employed, thus enabling the apparatus to be attached to various materials regardless of the size and type of object materials to measure residual stress.

Abstract: The present invention relates to an apparatus for indentation test, for measuring mechanical properties in the field. The present invention provides an apparatus which is suitable for measuring mechanical properties without compensative experimental constant for the analysis of measured data. The present invention provides an apparatus which is safe for testing the materials by utilizing a sensor for controlling indenter movement.

Abstract: The present invention relates to an apparatus for indentation test, a method for measuring data of indentation test and mechanical properties using the apparatus, and recording means for storing the method for measuring mechanical properties. It relates to the apparatus for making the indentation testing continuously attached to the tested materials and evaluating tensile properties directly in field through analyzing the measured data using notebook computer connected to interface system, method for measuring data of indentation test and mechanical properties using the apparatus, and recording means for storing the method for measuring mechanical properties. The present invention provides an apparatus which is easily attached to the structures/facilities by miniaturizing of the apparatus and is used for materials irrespective of its size or kinds by adopting diversified attaching means for indentation test.