Development Of Portable Ultrasonic Guided Wave Testing System For Guardrail Posts And Experimental Investigations

As energy absorbing mechanism, expressway guardrail can effectively absorb thevehicle impact and slow the vehicle speed to prevent the vehicle out of theexpressway. Post is one of main bearing components of guardrail. Therefore, it is vitalfor post embedment length measurement for ensuring the construction quality ofguardrail structure. Based on ultrasonic guided wave technology designed anddeveloped a portable probe, through the structural and process optimization makesportable probe and the coupling between the posts convenient and stable detection ofthe echo signal, the signal amplitude and signal-to-noise ratio can meet the testingrequirements, constitute guardrail post length detecting hardware system.To achieve rapid and accurate detection of column length, design anddevelopment of ultrasonic guided wave fence column length detection software, anddesigned two versions to adapt to different environments testing requirements.By detecting software using pulse-echo, pitch-catch, automatic scanning andother detection methods for free posts and buried posts detailed testing, analysis of thethree detection methods can achieve very good detection. Different methods indifferent test conditions to reflect its most important feature: Routine testing shouldadopt pulse-echo; condition is unknown should adopt automatic scanning; complexconditions should adopt pitch-catch manner.Using a portable probe with pulse-echo, pitch-catch detect the axial andcircumferential detection of free post and buried post，and come to the researchsummary: single probe testing should be kept away from the weld line andthrough-hole and surface selection roughness lower position; using two probes on theposts when probes were not simultaneously in the weld line can meet testingrequirements; the conclusion of pilot study that two probes are made into a paralleloverall probe and double crystal probe is that it can achieve testing requirements, andits detection characteristics is that two parallel probes compared to reverse parallelprobes detection signal has a greater amplitude in wave packet and easier todistinguish, while reverse parallel probes test the wave packet is always in the samelocation, to facilitate mutual authentication in different positions of the post, there is abetter stability of the wave packet.