An earlier Sandia report, SAND-91-7095, predates the Material Point Method's 1993 founding papers by at least a year

material-point-methodsandiasulskyprimary-source-verificationhistory-of-computingcomputational-mechanics

OSTI.GOV — the U.S. Department of Energy's own technical-report catalog — carries a record for "The application of a material-spatial numerical method to penetration" by Sulsky, Chen and Schreyer, report number SAND-91-7095. This is a distinct report from SAND93-7044, the 1993 technical report the vault's existing account of MPM's origin already rests on. SAND-91-7095's own OSTI catalog date is 1992, a full year ahead of the "started in 1993" framing that note's title still carries.

OSTI holds two separate catalog entries for what is evidently the same underlying report (OSTI IDs 5900384 and 10118944) — identical title, identical author list, identical report number, no digital full text attached to either. One entry displays a "Dec 31 1991" timestamp against the other's bare "1992"; this reads as a UTC-midnight display artifact of the same year field rather than a second, independently confirmed date, so this note records 1992 as the citation year and treats the day-level discrepancy as noise, not evidence of an earlier date still. The report's DOE contract number (AC04-76DP00789) also differs from the AC-1801 credited on SAND93-7044 and the 1994 CMAME paper — plausibly Sandia's general operating contract versus a specific research contract, but this was not independently confirmed and is not load-bearing to the dating claim above.

This is a historical/dating claim that directly narrows a date already resting in the vault, so per the sourcing floor's escalation rule it needs Tier 1–2, not Tier 3–4. It clears that bar as the government's own primary bibliographic record of its own funded report.