fix: Handle inconsistant SPH header between versions

There was an undocumented DB change between old and new versions where isphfg(1) can be 10 or 11. Data flag handling was modified to handle this behaviour.

Author: DCHartlen

src/lasso/dyna/d3plot.py

@@ -2158,7 +2158,15 @@ def _read_fluid_material_data(self):
         LOGGER.debug("_read_fluid_material_data end at byte %d", self.geometry_section_size)
 
     def _read_sph_element_data_flags(self):
-        """Read the sph element data flags"""
+        """Read the sph element data flags
+
+        The LS-DYNA database has some undocumented behaviour between older and newer
+        versions that impact how SPH header data is handled. The manual idnicates that
+        isphfg(1) should always be 11. However, in versions of LS-DYNA newer than R9,
+        isphfg(1) can be either 10 or 11 as history variables are handled differently.
+        Special handling was needed to ensure that old behaviour broken while handling
+        this undocumented change.
+        """
 
         if not self._buffer:
             return
@@ -2198,14 +2206,12 @@ def _read_sph_element_data_flags(self):
         self._sph_info.has_strainrate = sph_header_data["isphfg9"] > 6
         self._sph_info.has_true_strains = sph_header_data["isphfg9"] < 0
         self._sph_info.has_mass = sph_header_data["isphfg10"] != 0
-        self._sph_info.n_sph_history_vars = sph_header_data["isphfg11"]
-
-        if self._sph_info.n_sph_array_length != 11:
-            msg = (
-                "Detected inconsistency: "
-                f"isphfg = {self._sph_info.n_sph_array_length} but must be 11."
-            )
-            raise RuntimeError(msg)
+        # If isphfg1 = 10, then there are no history variables by default and isphfg11
+        # is filled with junk data that causes issues calculating n_sph_vars below
+        if sph_header_data["isphfg1"] == 10:
+            self._sph_info.n_sph_history_vars = 0
+        else:
+            self._sph_info.n_sph_history_vars = sph_header_data["isphfg11"]
 
         self._sph_info.n_sph_vars = (
             sph_header_data["isphfg2"]
@@ -2217,7 +2223,7 @@ def _read_sph_element_data_flags(self):
             + sph_header_data["isphfg8"]
             + abs(sph_header_data["isphfg9"])
             + sph_header_data["isphfg10"]
-            + sph_header_data["isphfg11"]
+            + self._sph_info.n_sph_history_vars
             + 1
         )  # material number