美国(FMI)Foundation Mechanics Inc
1969年，Foundation Mechanics Inc(FMI)公司成立于美国加州，为Wyle实验室的下属机构。而Wyle是最近50年来航空与原子能工业测试与测试设备设计领域的行业领导者。目前，FMI公司已是私有的设备制造供应商，是专门致力于设计和制造路面动态检测系统的著名供应商。在1970年出品了第一件路面检测设备“Road Rater”道路评价系统，随后在1972年出品了“Pavement Profiler”路面断面仪，1987年开始生产JILS FWD落锤弯沉仪。
今天，FMI以JILS FWD而闻名世界，为全球用户设计并制造动态路面承载系统。产品早已获得优良声誉，具有优越的性能，精确、可靠。如今，用户已遍布美国各州、大小城市、甚至私有机构和其他各国。FMI公司同时也为客户专门设计制造“用户定义化”的路面和地基的测试系统设备，并为医用及航空领域设计和制造动态承载系统。


In 1969, Foundation Mechanics, Inc. was incorporated in the state of California as a subsidiary of Wyle Laboratories. Wyle Laboratories had been a leader in testing and in the design of testing systems for the aerospace and nuclear industry for nearly fifty years. Foundation Mechanics, Inc. (FMI) is now privately held and operates from its world headquarters near the Los Angeles airport in El Segundo, California. FMI has been designing and building dynamic pavement testing systems since its inception. The Road Rater™ was built in 1970, followed by the Pavement Profiler in 1972, and then the JILS-FWD in 1987.


Today, FMI, now known and marketed as JILS, produces dynamic custom-designed pavement and foundation loading and testing systems for state, county, and city departments, private agencies, medical and aerospace applications, and numerous other entities world-wide. All JILS systems are well supported and have earned a strong reputation for performance, accuracy and reliability.


A falling weight deflectometer, or FWD for short, is a testing device used by civil engineers to evaluate the physical properties of a stretch of pavement. This could include (but is not limited to) highways, local roads, and airport runways. The machine is usually contained within a trailer that is driven to a location by another vehicle. At a pre-designated change in distance, the FWD device is deployed. A metal plate on the device is set up to strike the pavement at a given force, and sensors are placed around the plate and in a straight line radiating from the plate. These sensors record the deflections in the pavement (analogous to ripples in a pond) induced by the falling weight, hence the name "falling weight deflectometer".

This device has several practical purposes in determining the properties of pavement. For one, voids or empty spaces can be detected underneath the roadway. Joint testing determines how two abutting slabs of concrete or asphalt are fitting against one another. Other statical analyses determine the general strength of the structure, and can even predict what materials and in what combination were used to build the pavement if such information is unknown.