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Hsu, Peter C.

Publications and source records attributed to Hsu, Peter C..

11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Modeling of Thermal Decomposition of TATB-Based Explosive for Safety Analysis

We investigate and model the cook-off behavior of LX-17 to understand the response of explosive systems in abnormal thermal environments. Decomposition has been explored via conventional ODTX (One-Dimensional Time-to-eXplosion), PODTX (ODTX with pressure-measurement), TGA (Thermo-Gravimetric Analysis), and DSC (Differential Scanning Calorimetry) experiments under isothermal and ramped temperature profiles. The data were used to fit reaction rate parameters for proposed schemes in an ALE3D computational model. This model includes chemical reactions, thermo- and hydro-dynamics, and material properties, including thermal expansion, compressibility, and strength. These parameterizations were carried out utilizing a Python evolutionary optimization method on LLNL’s high-performance computing clusters. Additional experiments are being developed to further characterize and monitor decomposition intermediates to improve the model. Once experimentally validated, this model will be scalable to several applications involving LX-17. Furthermore, the optimization methodology developed herein should be applicable to other high explosive materials.

Chemistry - Chemical explosives↗
DOE OSTI2021

Low Temperature Time-to-Explosion Experiments on HMX in the LLNL's ODTX/P-ODTX System (FY 2020 Annual Report)

Over the last few decades, there has been a considerable research effort on the thermal decomposition and thermal explosion violence of energetic materials at elevated temperatures in different sample geometries and confinements. Thermal explosion studies on various energetic materials in two-dimensional geometry such as the Scaled-Thermal-Explosion-Experiment (STEX) system and the Sandia-Instrumented-Thermal-Ignition (SITI) system have been reported. The One-Dimensional Time to Explosion (ODTX) system, designed and built by LLNL, has been used since 1970s for thermal explosion studies. The system is attractive because of the one-dimensional geometry and minimal sample requirement. With the recent integration of a pressure monitoring element, the system can study pressure behavior of materials subjected to and during thermal exposure. Rapid pressure monitoring in µsec intervals allow for enhanced pressure determination in the time right before thermal explosion. The test data can be used for the validation of existing thermal models, particularly for introducing pressure terms. This report summarizes the efforts in performing small-scale safety tests, particle size measurements and conducting 7 ODTX/P-ODTX experiments on the Cl5 HMX material that Hunting uses for oil field applications.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Cook-off Study and Gas Pressure Measurement on HMX, LX-07, PBX 9502, and XTX-8004 in the P-ODTX System

Incidents caused by fire and other thermal events can heat energetic materials that may lead to thermal explosion and result in structural damage and casualty. Thus, it is important to understand the response of energetic materials to thermal insults. The One-Dimensional-Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory (LLNL) has been used for decades to characterize thermal safety of energetic materials. In this study, an integration of a pressure monitoring element has been added into the ODTX system (P-ODTX) to perform thermal explosion (cook-off) experiments on HMX, LX-07, PBX 9502, and XTX-8004. The P-ODTX testing generates useful data (cook-off temperature, cook-off time, and gas pressures) to assist with the thermal safety assessment of relevant energetic materials and components. This report summarizes the results of 24 P-ODTX experiments that were performed from May 2016 to July 2018 on the energetic materials. Recent upgrades to the data acquisition system allows for rapid pressure monitoring in microsecond intervals during thermal explosion. These pressure data are also included in the report. 6 P-ODTX experiments were also performed on detonators and a mock component and the test results will be summarized in a separate report.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Low Temperature Time-to-Explosion Experiments in the LLNL’s ODTX/P-ODTX System

Incidents caused by fire and some operations can heat energetic materials that may lead to thermal explosion and result in structural damage and casualty. Thus, explosive thermal sensitivity is an important topic for oilfield perforating operations and impacts perforating system performance and safety. Explosives have time-dependent temperature limits which can lead to thermal decomposition when exceeded and, under some circumstances, can result in performance losses and safety hazards. The One-Dimensional-Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory (LLNL) has been used for decades to characterize thermal safety of energetic materials. In this study, an integration of a pressure monitoring element has been added into the ODTX system (P-ODTX) to perform extended thermal experiments on HMX at three temperatures 160 °C, 170 °C and 185 °C. The tests generate time-temperature data as well as useful gas pressure data to assist with the thermal safety assessment of the energetics and systems that use the energetics. This report summarizes results of the 3 tests that were performed from July 2018 to November 2018.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Thermal Safety Characterization of HMX, LX-07, PBX 9502, and XTX-8004 in the ODTX System

Incidents caused by fire and combat operations can heat energetic materials that may lead to thermal explosion and result in structural damage and casualty. Some explosives may thermally explode at fairly low temperatures (< 100 C) and the violence from thermal explosion may cause a significant damage. Thus, it is important to understand the response of energetic materials to thermal insults. The One- Dimensional-Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory has been used for decades to measure times to thermal explosion, threshold thermal explosion temperature, and to determine the kinetic parameters of thermal decomposition of energetic materials. The kinetic parameters are being used to construct predictive models for thermal safety assessment on systems that use the energetic materials. Samples of different configurations (pressed part, powder, paste, and liquid) can be tested in the system. This report summarizes the results of our recent ODTX experiments on 4 energetic materials from 2016 to 2018: HMX (class 1 and class 2), LX-07 (two densities), PBX 9502 (two densities) and XTX-8004, lot C-639. Extensive P-ODTX testing was also performed on the 4 energetic materials and the results will be summarized in a separate report.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Effect of Sandpaper and Grain Size on Non‐Shock Initiated Reactions in HMX

Abstract Three grades of HMX samples, coarse (A), coarse with a small amount of fines (B), and ultra‐fine (F), were tested for impact sensitivity by ERL drop hammer. The Type 12A test used sandpapers of three different compositions, 120‐, 180‐grit Si/C and 180‐grit garnet. Reaction was accounted for by operator observation and microphone. The results showed different sensitivity for each of the HMX types. The F‐HMX was the smallest in average particle size and was the least sensitive to impact. The A‐HMX was the next most stable and the B‐HMX was the most sensitive to impact. The spent samples from the drop hammer testing of B‐HMX and F‐HMX were further evaluated with optical imaging. Conditions were selected that were near the DH 50 values of the specific HMX. Previous literature has cited localized hot spot formation to be the probable cause of non‐shock initiated reactions leading to impact sensitivity. This study yielded a plethora of samples exhibiting hot spots for HMX materials, both without and with proximity to grit particles. Hot spots in the proximity of grit particles gave the most dramatic hot spots, but both types of hot spots were exhibited in samples considered reacted and non‐reacted. The F‐HMX, even though the most stable to impact sensitivity, exhibited the most and best resolved hot spots of all the samples and conditions. Foreign objects were also observed in some of the samples. Previous work has shown metal particles coming from wear of the anvils used in the drop hammer experiment can also form hot spots. However, none of the samples here with metal particles exhibited, in proximity, hot spot formation.

Reynolds, John G.↗
DOE OSTI2016

The Enhancement of Gas Pressure Diagnostics in the P-ODTX System

The One Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory is a useful tool for thermal safety assessment of energetic material. It has been used since 1970s to measure times to explosion, threshold thermal explosion temperature, thermal explosion violence, and determine decomposition kinetic parameters of energetic materials. ODTX data obtained for the last 40 years can be found elsewhere.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

ONE-DIMENSIONAL TIME TO EXPLOSION (THERMAL SENSITIVITY) TESTS ON PETN, PBX-9407, LX-10, AND LX-17

Incidents caused by fire and combat operations can heat energetic materials that may lead to thermal explosion and result in structural damage and casualty. Some explosives may thermally explode at fairly low temperatures (< 100 C) and the violence from thermal explosion may cause a significant damage. Thus it is important to understand the response of energetic materials to thermal insults. The One Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory has been used for decades to measure times to thermal explosion, threshold thermal explosion temperature, and determine the kinetic parameters of thermal decomposition of energetic materials. Samples of different configurations (pressed part, powder, paste, and liquid) can be tested in the system. The ODTX testing can also provide useful data for assessing the thermal explosion violence of energetic materials. This report summarizes the results of our recent ODTX experiments on PETN powder, PBX-9407 pressed part, LX-10 pressed part, LX-17 pressed part and compares the test data that were obtained decades ago with the older version of ODTX system. Test results show the thermal sensitivity of various materials tested in the following order: PETN> PBX-9407 > LX-10 > LX-17.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Integrated Data Collection Analysis (IDCA) Program - Statistical Analysis of RDX Standard Data Sets

The Integrated Data Collection Analysis (IDCA) program is conducting a Proficiency Test for Small- Scale Safety and Thermal (SSST) testing of homemade explosives (HMEs). Described here are statistical analyses of the results for impact, friction, electrostatic discharge, and differential scanning calorimetry analysis of the RDX Type II Class 5 standard. The material was tested as a well-characterized standard several times during the proficiency study to assess differences among participants and the range of results that may arise for well-behaved explosive materials. The analyses show that there are detectable differences among the results from IDCA participants. While these differences are statistically significant, most of them can be disregarded for comparison purposes to assess potential variability when laboratories attempt to measure identical samples using methods assumed to be nominally the same. The results presented in this report include the average sensitivity results for the IDCA participants and the ranges of values obtained. The ranges represent variation about the mean values of the tests of between 26% and 42%. The magnitude of this variation is attributed to differences in operator, method, and environment as well as the use of different instruments that are also of varying age. The results appear to be a good representation of the broader safety testing community based on the range of methods, instruments, and environments included in the IDCA Proficiency Test.

round-robin test↗