Factors influencing impact force profile and measurement accuracy in drop weight impact tests

• Published in: International journal of impact engineering Vol. 145; p. 103688
• Main Authors: Li, Huawei, Chen, Wensu, Hao, Hong
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.11.2020; Elsevier BV
• Subjects: Contact force; Drop tests; Drop weight; Force measurement; Impact force profile; Impact loads; Load cell; Load cells; Mass distribution; Mass ratio; RC beam; Stiffness; Weight; Load cell; RC beam; Drop weight; Mass ratio; Impact force profile
• ISSN: 0734-743X; 1879-3509
• DOI: 10.1016/j.ijimpeng.2020.103688

•Measurement methods of impact force are summarized.•The influence of drop weight mass distribution on impact force measurement.•The effect of load cell location on impact force measurement and impact force profile.•The effect of mass ratio of drop weight to beam on impact force profile.•Three types of impact force profiles (Type I, II, III) are categorized and discussed. Drop weight tests on RC beams have been intensively reported in literature. Load cells are commonly used to measure the impact force acting on the beam. Different researchers adopted different configurations, e.g., location of load cells in the test, which could affect the impact load measurement. Although various impact force profiles have been reported by different researchers, there is no systematic study regarding the influences of the test setup on the measured impact forces. Therefore, this study numerically investigates the influences of test setups on impact force measurement accuracy and impact force profile of RC beam under drop weight impact. It is found that when the load cell is embedded into drop weight, the mass distribution of drop weight causes the measured impact force to deviate from the actual contact force acting on the beam. To obtain the true impact force recorded by the load cell mounted at the rear of drop weight head, the drop weight mass ratio αd (i.e., mass of the drop-weight to mass of the head) should be lower than 20. Placing load cell between drop weight and beam changes the local contact stiffness of impact zone and thus leads to different impact force profiles. In addition, the drop weight to beam mass ratio within the range of 0.5 and 4.0 affects the relative velocity between drop weight and beam after the first impulse and hence results in different impact force profiles.