{'fraction_non_alphanumeric': 0.025954198473282442, 'fraction_numerical': 0.0, 'mean_word_length': 5.626262626262626, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Large Mass Protection with Close-celled Metallic Foams Under Low Velocity Impact: Spring-damper-foam Collision Model

Abstract The vibration isolation and energy absorption capability of high porosity metallic foams with closed cells for large mass protection under low velocity impact is theoretically studied. To explore the underlying physical mechanisms of shock attenuation, a double degree of freedom (DDF) spring-damper-foam collision model is developed. The effects of key system parameters (such as spring stiffness, damping ratio, mass ratio, initial velocity and foam thickness) on optimal foam mass and minimum acceleration peak are discussed.