# US 11,906,593 B2 · Method and system for testing the structural integrity of a metal joint > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,906,593 B2 - Document ID: US11906593B2 - Status: Granted - Kind: B2 - Application number: 17/007,218 - Filed: 2020-08-31 - Published: 2021-05-06 - Granted: 2024-02-20 - Earliest claimed: 2019-10-31 - Assignees: Keysight Technologies, Inc. - Applicants: Keysight Technologies, Inc. - Inventors: Manuel Kasper; Manuel Moertelmaier - Web page: https://patentgrep.com/patent/US11906593B2 ## CPC - G01R 31/389: Measuring internal impedance, internal conductance or related variables - B23K 31/02: relating to soldering or welding - B23K 31/125: {Weld quality monitoring} - G01N 27/041: {of a solid body} - G01N 27/20: Investigating the presence of flaws - G01R 27/14: Measuring resistance by measuring current or voltage obtained from a reference source (G01R27/16, G01R27/20, G01R27/22 take precedence) - G01R 31/382: Arrangements for monitoring battery or accumulator variables, e.g. SoC - G01R 31/66: Testing of connections, e.g. of plugs or non-disconnectable joints (testing for incorrect line connections G01R31/55) - B23K 2101/36: Electric or electronic devices - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract A method is for testing the structural integrity of a metal joint such as a weld. The method includes applying stress to the metal joint, and measuring a resistance of a circuit including the metal joint during application of the stress to the metal joint. A structural integrity of the metal joint is determined by comparing the measured resistance with a baseline resistance. ## Claims ### Claim 1 A method of testing a structural integrity of a metal joint, comprising applying stress to the metal joint; measuring a resistance of a circuit including the metal joint during application of the stress to the metal joint using a four-terminal (4T) sensing method by separate pairs of current-carrying electrodes and voltage-sensing electrodes, wherein the measured resistance, and baseline resistances are respectively obtained from a real part of a measured complex impedance of the metal joint under stress and a real part of a measured complex impedance of the metal joint not under stress; and determining a structural integrity of the metal joint according to a magnitude of a difference between the measured resistance and the baseline resistance. ### Claim 2 (depends on 1) The method of claim 1, wherein the metal joint is a weld. ### Claim 3 (depends on 1) The method of claim 1, wherein the metal joint is a weld of a battery. ### Claim 4 (depends on 1) The method of claim 1, wherein the stress is at least one of mechanical stress, thermal stress, acoustic stress and electrical stress. ### Claim 5 (depends on 4) The method of claim 4, wherein the stress is applied by driving an electric current through the metal joint. ### Claim 6 (depends on 5) The method of claim 5, wherein the electric current is a pulsed DC current. ### Claim 7 (depends on 4) The method of claim 4, wherein the stress is applied by a mechanical actuator. ### Claim 8 (depends on 1) he method of claim 1, further comprising obtaining the baseline resistance by measuring a resistance of the metal joint in the absence of stress applied to the metal joint. ### Claim 9 A system for testing a structural integrity of a metal joint, comprising: a stimulus device configured to stress the metal joint; a resistance measuring device configured to measure a resistance of the metal joint while the metal joint is stressed by the stimulus device, wherein the resistance is measured using a four-terminal (4T) sensing method by separate pairs of current-carrying electrodes and voltage-sensing electrodes; and a test automation platform, comprising a memory that stores executable instructions, and a processor configured to execute the instructions retrieved from the memory, wherein the instructions, when executed, cause the processor to determine a structural integrity of the metal joint based on a comparison between the measured resistance and a baseline resistance, wherein: the resistance measuring device is configured to measure a complex impedance of the metal joint while the metal joint is under stress; and the instructions, when executed by the processor, cause the processor to determine a difference between a real component of the measured impedance and the baseline resistance. ### Claim 10 (depends on 9) The system of claim 9, wherein the stimulus device and the resistance measuring device operate under control of the test automation platform. ### Claim 11 (depends on 9) The system of claim 9, wherein the stress is at least one of mechanical stress, thermal stress, acoustic stress and electrical stress. ### Claim 12 (depends on 9) The system of claim 9, wherein the stimulus device includes a mechanical actuator configured to apply mechanical stress to the metal joint. ### Claim 13 (depends on 9) The system of claim 9, wherein the stimulus device includes a current source configured to apply a pulsed DC current across the metal joint. ### Claim 14 (depends on 9) The system of claim 9, wherein the metal joint is a weld. ### Claim 15 A method of testing a structural integrity of a metal joint, comprising: measuring a resistance of the metal joint to obtain a baseline impedance of the metal joint; applying stress to the metal joint; measuring a resistance of the metal joint during application of the stress to the metal joint using a four-terminal (4T) sensing method by separate pairs of current-carrying electrodes and voltage-sensing electrodes to obtain a stressed resistance of the weld; determining a measured difference between the baseline resistance of the metal joint and the stressed resistance of the metal joint; and comparing the measured difference to a threshold value, wherein a test result is a lack structural integrity when the measure difference exceeds the threshold value, wherein the measured and baseline resistances are respectively obtained from a real part of a measured complex impedance of the metal joint under stress and a real part of a measured complex impedance of the metal joint not under stress. ### Claim 16 (depends on 15) The method of claim 15, wherein the metal joint is a weld. ### Claim 17 (depends on 15) The method of claim 15, wherein the stress is at least one of mechanical stress, thermal stress, acoustic stress and electrical stress.