| As an important device, automobile cab must have enough rigidity andintensity. Because of the limits of the structure and the energy region is finity, thecab of flat truck usually has many problems, such as too large deflection, occupanthurts, and so on. So the safety strength must have an enough attention. In abroad,the safety strength is usually examined by pendulum impact testing and relativecode safety regular is enforced. Our country has not any code or standards yet inthis area. FAW developed a pendulum frontal impact cab test system according thestandards of Europe (ECE29) and some experiments have been already carried out.Although experiment is still the terminal method to estimate the passive safety, italso has many problems, such as needing sample vehicle, high cost, longdevelopment cycle, and so on. This paper is to simulate the pendulum impact cabtest for trucks with the finite element method, to analysis the dynamic responds.Using the energy theory of thin metal sheet and computer simulation technology inthe frontal truck cab impact test.According to the experimental equipment and standards of the pendulumimpact testing system, based on ADAMS software a virtual prototype model is setup and a kinematics simulation is carried out. The simulation results can be asinitial conditions for the simulation of cab impacted by pendulum.Appling the stress wave theory of the impacting dynamics, the relationbetween the pendulum's initial speed and impacted plane response mode isanalyzed, and the following conclusions can be drawn:If the initial rate of pendulum is less than 3.951(m/s), collisions is elasticcollision, and only cause the elastic deformation. If the initial rate of pendulum is3.951~99.65 (m/s), the response of impacted plane is plastic deformation. If theinitial rate of pendulum is 99.65~4700 (m/s), the response of impacted plane isdimensional hydrodynamic deformation.According to Calder's and Goldsmith's energy theory of elastic-plastic sheetmetal, response of cab to pendulum, mathematical models of the largestdisplacement can be obtained:For example,for CA150PL2 cab, the largest displacement caused by frontalimpacted were calculated. According to the mathematical model of the cab's largestdisplacement after the pendulum impact, we can know: if pendulum impact speedand impact energy identified, according to the occupant's location and relevantprotective measures to advance enactment the change of the largest displacement ofcab. We can forwardly launch a reasonable size of the cab's structure, and make thecab's preparative coefficient of intensity in a suitable range to the design withintensity.According to the structure size of the researched model of car, a CATIA modelis constructed. Finite element grid is meshed with the software of Hypermesh. Forthe large deformation and large displacement of the nonlinearity impact, the paperchooses ANSYS/LS-DYNA as the simulation tood, and than, with the aided ofpreprocessing and post processing tool and solution of ANSYS/LS-DYNA, theFEM is solved.According the analysis of the response after the impact taken place, an safetyestimation is made, and the disciplinarian of the displacement (37.2mm), stressforce and deformation is generalized. The result accords with relative theories.And the reliability is examined. The simulation result compared with theexperimental data, and the source of difference is analyzed, and someimprovement opinion is provided,and the modifications for bumper structure areput forward.It is demonstrated in this paper that the reliability of truck cab crashworthinesscan be tremendously increased by means of the simulation techniques in designstage and it is possible that the car impact performance can be evaluated andimproved even before the trial-produced model come into being. Simulationtechniques can significantly save development time and cost, and It provides abasis for ameliorate structure and optimize design of the equipment and it is alsouseful to constitute the safe code of truck cab impacted.
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