Blast Effects & Damage Assessment Flashcards
7 cards from real CES practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Blast Effects & Damage Assessment flashcards as text
The Mach stem forms during a surface burst when:
Answer: The incident and reflected waves merge along the ground surface
The Mach stem is a near-vertical, reinforced shock front created when the incident wave and the ground-reflected wave coalesce at a specific angle.
Cratering from a buried explosive is classified as 'camouflet' when:
Answer: No surface rupture occurs and only a subsurface cavity is formed
A camouflet is an underground explosion that creates a subsurface void without breaking the surface, leaving no visible crater.
Which metric is used to compare the brisance of different explosives?
Answer: Plate dent test (copper crusher) value
The plate dent (or copper crusher) test measures the depth of indentation caused by detonation, providing a comparative brisance index.
In blast damage assessment of reinforced concrete, spalling on the distal face (far side from blast) indicates:
Answer: Reflected tensile stress exceeding the concrete's tensile strength
Spalling on the far face occurs when the compressive wave reflects as a tensile wave, and concrete — weak in tension — fractures and ejects material.
The TNT equivalence factor for a non-TNT explosive is determined by comparing:
Answer: Heat of explosion values or peak overpressure at a reference distance
TNT equivalence is derived from either thermochemical heat of explosion ratios or empirical overpressure measurements referenced to TNT at the same standoff.
What is the primary purpose of a pressure-time (P-t) recorder placed at a field blast test?
Answer: To record overpressure history and calculate impulse
A P-t recorder captures the pressure waveform over time, from which both peak overpressure and impulse can be derived for blast characterization.
Which building component typically fails FIRST under a far-field blast (low overpressure) scenario?
Answer: Window glazing
Window glazing has low resistance to blast overpressure and fails at pressures as low as 0.5–1 psi, well before structural elements.